University of Ghana http://ugspace.ug.edu.gh UNIVERSITY OF GHANA COLLEGE OF BASIC AND APPLIED SCIENCE PALYNOLOGY, PALYNOFACIES AND ORGANIC GEOCHEMICAL ANALYSES OF CRETACEOUS AND EARLY PALEOGENE SEDIMENTS, OFFSHORE TANO BASIN, WESTERN GHANA BY CHRISTOPHER ALIRAH ACHAEGAKWO (10193563) THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF DEGREE OF DOCTOR OF PHILOSOPHY IN EARTH SCIENCE EARTH SCIENCE DEPARTMENT SEPTEMBER, 2021. University of Ghana http://ugspace.ug.edu.gh DECLARATION This is to certify that this thesis is the result of research carried out by Christopher A. Achaegakwo towards the award of Doctor of Philosophy Degree in Earth Science from the Department of Earth Science, University of Ghana, under the supervision of Prof. David Atta- Peters, Prof. Daniel K. Asiedu and Prof. Chris Y. Anani. Signature: Date..... 0..1../.0..1../.2..0..2..3.. ................... Christopher A. Achaegakwo (10193563) (Student) Signature: Date.....0..5../.0..1../..2..0..2..3.. .................. Prof. David Atta-Peters (Principal Supervisor) Signature: Date.....0..5../.0..1../.2..0..2..3.. ................... Prof. Daniel K. Asiedu (Co-Supervisor) Signature: Date.......0..5../.0..1../.2..0..2..3.. ................. Prof. Chris Y. Anani (Co-Supervisor) i University of Ghana http://ugspace.ug.edu.gh ABSTRACT Palynological analysis from two exploratory and one appraisal wells (Lynx-1X, Dzata-1 and Dzata-2A) and organic geochemical results from two wells (Dzata-1 and Dzata-2A) samples were obtained from the Middle Cretaceous-Early Tertiary of the Deepwater Cape Three Points offshore Tano Basin, Western Ghana. From the rich and well preserved palynomorphs recovered, the First Appearance Datum (FAD) and Last Appearance Datum (LAD) of stratigraphically significant species were used to propose four palynozones (PZ-I to PZ-IV) for the samples. Lynx-1X is Albian-Eocene, Dzata-1 and Dzata-2A wells are dated Albian- Maastrichtian, based on evidence of stratigraphically significant sporomorphs and dinocysts. The sporomorph associations recovered from the three wells exhibit similarity to Cretaceous Phytogeographic Provinces of African-South America (ASA). Sporomorphs recorded are characteristic of Albian-Cenomanian Elaterate Province for the deeper intervals and of the Senonian Palmae Province for the shallower intervals in all the wells. The Late Cretaceous peridineacean assemblage has a lot of similarity with those of Malloy or Tropical/Subtropical suite of Lentin and Williams (1980). Distribution of palynomorphs enabled the identification of two major sedimentary facies: the nearshore and open marine facies. The nearshore facies, concentrated at deeper intervals, are characterized by abundant sporomorphs and peridinoid dinocysts while the open marine facies are dominated by gonyaulacoid dinocysts and are restricted to the shallower intervals. This occurred as a result of marine transgression which flooded the area causing marine sedimentation. ii University of Ghana http://ugspace.ug.edu.gh Palynofacies analysis carried out under transmitted microscopy defined seven palynofacies associations (PF-1 to PF-7) for Lynx-1X, five palynofacies associations (PT-1 to PT-5) for Dzata-1 and six palynofacies associations (PT-A to PT-F) for Dzata-2A wells. The first palynofacies assemblage in Lynx-1X well, PF-1, reflects deposition in a fluvio- deltaic/nearshore environment under a marginal dysoxic-anoxic basin condition with sediments typical of kerogen type III-IV (gas prone). PF-2 is deposited under a proximal suboxic-anoxic shelf conditions in a marginal marine/nearshore environment and sediments classified as kerogen type II/III (gas prone). PF-3 suggests deposition in a marginal marine to shallow marine environment under distal suboxic-anoxic conditions suggesting kerogen type II>I (highly oil prone). PF-4 is inferred to be deposited under a distal suboxic-anoxic basin condition in a shallow marine environment and sediments characterized by kerogen type II>I (highly oil prone). PF-5 indicates a deposition under a distal dysoxic-oxic shelf conditions in middle-outer neritic environment depicting kerogen type II>I (oil prone). PF-6 suggests a deposition in a shelf to basin transition condition in the inner-middle neritic environments indicating kerogen type III and II (oil prone). PF-7 reflects an outer neritic environment under distal mud-dominated oxic shelf conditions and characterized by kerogen type II/III (gas prone). In Dzata-1 well, PT-1 suggests deposition in a nearshore environment under proximal suboxic- anoxic conditions with sediments typical of kerogen type II and III (oil prone). PT-2 indicates deposition in a dysoxic-suboxic conditions in a nearshore environment typifying kerogen type III (gas prone). PT-3 suggests deposition in a marginal dysoxic-anoxic basin condition in a fluvio-deltaic/nearshore environment typical of kerogen type III (gas prone). PF-4 represents inner-middle neritic to outer neritic environment deposited in distal dysoxic-oxic shelf conditions typifying kerogen type II>I (oil prone). PT-5 represents deposition in a nearshore iii University of Ghana http://ugspace.ug.edu.gh environment under marginal dysoxic-anoxic basin conditions which is characterized by kerogen type III (gas prone). PT-A of Dzata-2A well indicates deposition in a nearshore to shallow marine (inner neritic) environment under a proximal suboxic-anoxic shelf condition with typical type II/III kerogen (oil prone). PT-B infers an inner neritic/nearshore depositional environment under dysoxic- suboxic conditions with facies characterized by kerogen type III or II (gas prone). PT-C is deposited under a distal dysoxic-oxic shelf conditions in environments ranging from nearshore/inner neritic to middle-outer neritic characteristic of kerogen type II>I (oil prone). PT-D indicates a nearshore/inner neritic depositional environment under marginal dysoxic anoxic basin conditions and facies constituted by kerogen type III (gas prone). PT-E suggests deposition in inner-outer neritic environment under distal suboxic-anoxic basin condition characteristic of kerogen type II≥I (highly oil prone). PT-F suggests a deposition in a nearshore/shallow marine environment under a distal dysoxic-anoxic shelf environment with facies characterized by kerogen type II/III (oil prone). Rock-Eval pyrolysis and TOC results for Lynx-1X and Dzata-2A wells indicates that most of the analyzed samples are thermally immature to marginally mature and have a good petroleum potential with the ?Turonian-Santonian age samples as a better potential source rocks than the Campanian-Eocene and Albian-Cenomanian source samples. Analyzed samples generally have low kerogen conversion. iv University of Ghana http://ugspace.ug.edu.gh DEDICATION This work is dedicated to the Almighty God, my parents, siblings and all my friends. v University of Ghana http://ugspace.ug.edu.gh ACKNOWLEDGEMENTS I give thanks to the Almighty God for seeing me through this work. This thesis has been completed at the Department of Earth Science, University of Ghana, under the supervision of Prof. David Atta-Peters, Prof. Daniel K. Asiedu and Prof. Chris Y. Anani whose guidance and help are greatly appreciated. I am indebted particularly to Prof. David Atta-Peters who agreed to provide principal supervision of this work with his useful suggestions and continuous follow- up are a real push to this work. I am extremely grateful to my co-supervisors Prof. Daniel K. Asiedu and Prof. Chris Y. Anani for their close supervision and encouragement during the write up. Laboratory analysis of the palynological samples were undertaken at the Geolab, Faculty of Geoscience, Utrecht University, The Netherlands; the support of the staff at the Department of Earth Science, Utrecht University are deeply appreciated. I would also like to extend my gratitude to Prof. Bas van de Schootbrugge who supervised my work with valuable suggestions at the Department of Earth Science, Utrecht University. Special thanks to Prof. Patrick Asamoah Sakyi, Prof. Sandow Mark Yidana and Prof. Thomas MBA Akabzaa. I would like also to express my appreciation to all my friends and colleagues for their unlimited support at various occasions. The scholarship provided by the Ghana Education Trust Fund (GETFUND) is greatly acknowledged and made this work possible. Special thanks and gratitude to all the staff at the Department of Earth science, University of Ghana; Department of Earth Science, Utrecht University, The Netherlands; British Geological Survey (BGS), Keyworth, Nottingham, UK who contributed to the success of this work. I am deeply grateful to all staff of the Petroleum Commission of Ghana and Ghana National Petroleum Corporation (GNPC) for working together to provide me with the data for this successful work. Finally, this work would not be possible without the support and patience of my family and friends to whom I am particularly grateful. vi University of Ghana http://ugspace.ug.edu.gh TABLE OF CONTENT DECLARATION ........................................................................................................................ i ABSTRACT ............................................................................................................................... ii DEDICATION ........................................................................................................................... v ACKNOWLEDGEMENTS ...................................................................................................... vi LIST OF FIGURES .............................................................................................................. xiv LIST OF TABLES ................................................................................................................... xx CHAPTER ONE ........................................................................................................................ 1 INTRODUCTION ..................................................................................................................... 1 1.1 BACKGROUND .............................................................................................................. 1 1.2 PROBLEM STATEMENT AND JUSTIFICATION ...................................................... 2 1.3 AIMS AND OBJECTIVES OF STUDY ......................................................................... 3 1.3.1 General overview of the geology of Ghana. .............................................................. 4 1.3.1.1 The Western units ............................................................................................... 4 1.3.1.2 The Pan-African Dahomeyide Belt ........................................................................ 6 1.3.1.3 The Voltaian ........................................................................................................ 7 1.3.1.4 The Coastal Sediments ........................................................................................ 9 1.4 STUDY AREA ............................................................................................................... 10 1.5 GEOLOGY AND TECTONICS OF THE TANO BASIN ........................................ 10 1.6 STRATIGRAPHY OF THE TANO BASIN ................................................................. 14 1.6.1 Lower Cretaceous Section ....................................................................................... 14 vii University of Ghana http://ugspace.ug.edu.gh 1.6.1.1 Lower Albian (Kobnaswaso Formation) .......................................................... 14 1.6.1.2 B-Shale (Bonyere Formation) ........................................................................... 15 1.6.1.3 Middle to Upper Albian .................................................................................... 15 1.6.2 The Upper Cretaceous Section ................................................................................ 16 1.6.2.1 Cenomanian Limestone .................................................................................... 16 1.6.2.2 Turonian to Upper Santonian ............................................................................ 16 1.6.2.3 Campanian ........................................................................................................ 17 1.6.2.4 Maastrichtian ..................................................................................................... 17 1.6.3 The Tertiary Section ................................................................................................ 18 1.6.3.1 Paleocene, Eocene, Oligocene and Miocene .................................................... 18 1.7 PETROLEUM EXPLORATION AND EXPLOITATION HISTORY IN THE TANO BASIN. ................................................................................................................................. 18 CHAPTER TWO ..................................................................................................................... 22 LITERATURE REVIEW ........................................................................................................ 22 2.1 PREVIOUS PALYNOLOGICAL WORK IN THE STUDY AREA. ........................... 22 2.2 PREVIOUS SOURCE ROCK EVALUATION AND HYDROCARBON POTENTIAL OF THE TANO BASIN. ...................................................................................................... 26 CHAPTER THREE ................................................................................................................. 28 MATERIALS AND METHODS ............................................................................................. 28 3.1 MATERIALS ................................................................................................................. 28 3.1.1 The Lynx-1X well ................................................................................................... 28 3.1.1.1 Lithology of Lynx-1X. ......................................................................................... 28 viii University of Ghana http://ugspace.ug.edu.gh 3.1.2 Dzata-1 well. ............................................................................................................ 33 3.1.2.1 Lithology of Dzata-1. ........................................................................................ 33 3.1.3 The Dzata-2A well. .................................................................................................. 35 3.1.3.1 Lithology of Dzata-2A. ..................................................................................... 35 3.2 METHODS .................................................................................................................... 37 3.2.1 Sample preparation and palynological analysis. ...................................................... 37 3.2.2 Sample Processing Techniques. .............................................................................. 38 3.2.2.1 Sample Crushing and Drying. ........................................................................... 38 3.2.2.2 Pre-Hydrofluoric Acid (HF) Treatment ............................................................ 38 3.2.2.3 (38-40%) Hydrofluoric acid (HF) treatment ..................................................... 39 3.2.2.4 Sieving, Ultrasonification and Centrifuging. .................................................... 40 3.2.2.5 Oxidation. .......................................................................................................... 40 3.2.2.6 Mounting. .......................................................................................................... 40 3.2.3 Microscopic Study and Photomicrography. ............................................................ 41 3.2.4 Repository ................................................................................................................ 42 3.2.5 Palynofacies and Palaeoenvironmental Analysis. ................................................... 42 3.2.6 Geochemical Analysis ............................................................................................. 43 CHAPTER FOUR .................................................................................................................... 44 PALYNOSTRATIGRAPHY ................................................................................................... 44 4.1 INTRODUCTION .......................................................................................................... 44 4.2 PALYNOZONATION (PZ) AND AGE ASSIGNMENT ............................................. 45 ix University of Ghana http://ugspace.ug.edu.gh 4.2.1 Palynozone I (PZ-I): Afropollis jardinus-Sofrepites legouxae-Elaterocolpites castelaini Assemblage Zone ............................................................................................. 45 4.2.2 Palynozone II (PZ-II): Cretaceaeiporites polygonalis-C. scabratus-Dinogymnium accuminatum Assemblage Zone ....................................................................................... 56 4.2.3 Palynozone III (PZ-III): Trichodinium castanea-Cerodinium diebelli-Dinogymnium acuminatum Assemblage Zone ......................................................................................... 63 4.2.4 Palynozone IV (PZ-IV): Cerodinium diebelli-Apectodinium homomorphum- Homotryblium tenuispinosum Assemblage Zone ............................................................. 74 4.3 PALEOECOLOGY AND PALEOPROVINCES .......................................................... 81 4.3.1 Palaeoecological and paleoclimatic implications from sporomorphs ..................... 81 4.3.1.1 Paleofloral Provinces ........................................................................................ 83 4.3.1.1.1 The Pre-Albian Early Cretaceous Dicheiropollis etruscus/Afropollis Province. .................................................................................................................... 83 4.3.1.1.2 Albian-Cenomanian Elaterate Province ..................................................... 84 4.3.1.1.3 The Senonian Palmae Province .................................................................. 85 4.3.2 Paleoecological and paleoclimatic implications from dinoflagellates .................... 85 4.3.2.2 Dinoflagellates Provincialism ........................................................................... 94 CHAPTER FIVE ................................................................................................................... 126 PALYNOFACIES ANALYSIS AND PALAEOENVIRONMENTAL INTERPRETATIONS ................................................................................................................................................ 126 5.1 INTRODUCTION ........................................................................................................ 126 5.1.1 Classification of Palynofacies Constituents .......................................................... 128 x University of Ghana http://ugspace.ug.edu.gh 5.1.2 Structureless organic matter .................................................................................. 132 5.1.3 Structured organic matter ..................................................................................... 135 5.1.3.1 Phytoclasts (Translucent and Opaques (black debris)): .................................. 135 5.1.3.2 Palynomorphs ................................................................................................. 137 5.1.3.2.1. Marine palynomorphs: This includes dinoflagellate cysts, acritarchs and prasinophytes. .......................................................................................................... 137 5.1.3.2.2. Freshwater microplankton ....................................................................... 139 5.1.3.2.3. Zoomorph ................................................................................................ 139 5.1.3.2.4. Sporomorph (Terrestrial Palynomorphs): ............................................... 140 5.2 PALYNOFACIES ASSOCIATIONS AND PALAEOENVIRONMENTAL INTERPRETATIONS. ....................................................................................................... 142 5.2.1 Lynx-1X well ......................................................................................................... 147 5.2.1.1 Palynofacies type 1 (PF-1) (Opaque phytoclasts) dominant with moderate AOM). ......................................................................................................................... 147 5.2.1.2 Palynofacies type 2 (PF-2) (Equal abundance of AOM and Opaque phytoclasts). ................................................................................................................ 150 5.2.1.3 Palynofacies type 3 (PF-3) (AOM dominant with high opaques) .................. 154 5.2.1.4 Palynofacies type 4 (PF-4) (AOM dominant with relatively equal abundance of opaques and phytoclasts .............................................................................................. 157 5.2.1.5 Palynofacies type 5 (PF-5) (AOM dominant with palynomorphs) ................. 159 5.2.1.6 Palynofacies type 6 (PF-6) (AOM, phytoclasts and palynomorphs abundant). ..................................................................................................................................... 164 xi University of Ghana http://ugspace.ug.edu.gh 5.2.1.7 Palynofacies type 7 (PF-7) (Palynomorphs with equal abundance of AOM and opaques). ..................................................................................................................... 167 5.2.2 Dzata-1 well ........................................................................................................... 173 5.2.2.1 Palynofacies type 1 (PT-1) (AOM dominant with abundant Opaque phytoclasts) ................................................................................................................. 173 5.2.2.2 Palynofacies type 2 (PT-2) (Relatively equal abundance of opaques phytoclasts and phytoclasts (non-opaques) with AOM and palynomorphs). ................................ 177 5.2.2.3 Palynofacies type 3 (PT-3) (Opaques dominant) ............................................ 180 5.2.2.4 Palynofacies type 4 (PT-4) (AOM dominant with palynomorphs). ............... 183 5.2.2.5 Palynofacies type 5 (PT-5) (Abundant opaque phytoclasts and AOM). ........ 187 5.2.3 Dzata-2A ................................................................................................................ 192 5.2.3.1 Palynofacies type 1 (PT-A) (AOM dominant with abundant opaque phytoclasts). ................................................................................................................ 192 5.2.3.2 Palynofacies type 2 (PT-B) (Abundant AOM with relatively equal abundance of phytoclasts and palynomorphs) .............................................................................. 196 5.2.3.3 Palynofacies type 3 (PT-C) (AOM dominant with high palynomorphs). ....... 199 5.2.3.4 Palynofacies type 4 (PT-D) (Abundance of AOM and opaque phytoclasts with high translucent phytoclasts). ...................................................................................... 203 5.2.3.5 Palynofacies type 5 (PT-E) (AOM dominant) ................................................ 206 5.2.3.6 Palynofacies type 6 (PT-F) (AOM dominant with relatively equal abundance of translucent phytoclasts and palynomorphs). ............................................................... 209 CHAPTER SIX ...................................................................................................................... 214 SOURCE ROCK EVALUATION ......................................................................................... 214 xii University of Ghana http://ugspace.ug.edu.gh 6.1 INTRODUCTION ........................................................................................................ 214 6.2 METHODOLOGY ....................................................................................................... 215 6.3 EVALUATION OF LYNX-1X AND DZATA-2A WELLS ....................................... 218 6.3.1 Organic Carbon richness and Hydrocarbon Potential ........................................... 218 6.3.2 Kerogen Types ....................................................................................................... 224 6.3.3 Organic Matter Maturity ........................................................................................ 227 6.3.4 Expulsion Potential ................................................................................................ 232 CHAPTER SEVEN ............................................................................................................... 234 CONCLUSION ...................................................................................................................... 234 RECOMMENDATION……………………………………………………………………240 REFERENCES ...................................................................................................................... 241 APPENDICES ....................................................................................................................... 296 xiii University of Ghana http://ugspace.ug.edu.gh LIST OF FIGURES Figure 1.1. Simplified geological map of Ghana. ...................................................................... 6 Figure 1.2: Map of the Dahomeyide orogen in southeastern Ghana and adjoining part of Togo. .................................................................................................................................................... 8 Figure 1.3. Geological map of the Dahomeyide belt showing the Voltaian Supergroup. ......... 9 Figure 1.4: Map of Study area showing studied wells Offshore Tano Basin (Lynx-1, Dzata-1 and Dzata-2A). ......................................................................................................................... 10 Figure.1.5 Tano Basin within the St. Paul and Romanche transform fault zones. .................. 12 Figure 1.6. The General Stratigraphy of the Tano Basin. ........................................................ 19 Figure 3.1: Lithology of Lynx-1X, Dzata-1 and Dzata-2A wells. ........................................... 37 Figure 4.1: Age, palynozone, lithological column and stratigraphical significant taxa from Lynx-1X well. .......................................................................................................................... 60 Figure 4.2: Age, palynozone, lithological column and stratigraphical significant taxa from Dzata-1 well. ............................................................................................................................ 61 Figure 4.3: Age, palynozone, lithological column and stratigraphical significant taxa from Dzata-2A well. ......................................................................................................................... 62 Figure 4.4: Relative percentage composition distribution chart of dinocysts (marine palynomorphs) with spores and pollen (terrestrial palynomorphs) in Palynozone III and IV from Lynx-1X well…………………………………………………………………………..71 Figure 4.5: Relative percentage composition distribution chart of dinocysts (marine palynomorphs) with spores and pollen (terrestrial palynomorphs) of Palynozone III from Dzata-1 well. ............................................................................................................................ 72 Figure 4.6: Relative percentage composition distribution chart of dinocysts (marine palynomorphs) and spores and pollen (terrestrial palynomorphs) of Palynozone III from Dzata-2A well. ......................................................................................................................... 73 xiv University of Ghana http://ugspace.ug.edu.gh Figure 4.7: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in palynozone III of Lynx-1X well. ............................................................................................. 89 Figure 4.8: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in palynozone III of Dzata-1 well. ............................................................................................... 90 Figure 4.9: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in palynozone III of Dzata-2A well. ............................................................................................ 91 Figure 4.10: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in palynozone IV of Lynx-1X well. ............................................................................................. 92 Figure 4.11: Correlation of lithology, palynozones and depositional environments of Lynx- 1X, Dzata-2A and Dzata-1 wells…………………………………………………………….93 Figure 5.1: AOM-Palynomorphs-Phytoclasts (APP) ternary plot showing environment of deposition and kerogen types. ................................................................................................ 145 Figure 5.2: Representative photograph of palynofacies association and pie chart of PF-1 from Lynx-1X well. ........................................................................................................................ 149 Figure 5.3: APP Ternary diagram for PF-1 samples from Lynx-1X well. ............................ 150 Figure 5.4: Representative photograph of palynofacies association and pie chart of PF-2 from Lynx-1X well. ........................................................................................................................ 152 Figure 5.5: APP Ternary diagram of studied samples from the Lynx-1X well . ................... 153 Figure 5.6: MSP Ternary plot for PF-2 samples from Lynx-1X well. ................................... 153 Figure 5.7: Representative photograph of palynofacies association and pie chart of PF-3 from Lynx-1X well. ........................................................................................................................ 155 Figure 5.8: APP Ternary diagram for PF-3 samples from Lynx-1X well. ............................ 156 Figure 5.9. MSP Ternary plot of studied samples from the Lynx-1X well. .......................... 156 Figure 5.10: Representative photograph of palynofacies association and pie chart of PF-4 from Lynx-1X well. ........................................................................................................................ 158 Figure 5.11. APP Ternary diagram for PF-4 samples from Lynx-1X well. .......................... 159 xv University of Ghana http://ugspace.ug.edu.gh Figure 5.12: Representative photograph of palynofacies association and pie chart of PF-5 from Lynx-1X well. ........................................................................................................................ 162 Figure 5.13: APP Ternary diagram for PF-5 from Lynx-1X well. ........................................ 163 Figure 5.14: MSP Ternary plot for PF-5 samples from Lynx-1X well .................................. 163 Figure 5.15: Representative photograph of palynofacies association and pie chart of PF-6 from Lynx-1X well. ........................................................................................................................ 166 Figure 5.16: APP Ternary diagram for PF-6 samples from Lynx-1X well. .......................... 167 Figure 5.17: Representative photograph of palynofacies association and pie chart of PF-7 from Lynx-1X well. ........................................................................................................................ 169 Figure 5.18: APP Ternary diagram for PF-7 samples from Lynx-1X well ........................... 170 Figure 5.19: MSP Ternary plot for PF-7 samples from Lynx-1X well. ................................. 170 Figure 5.20: Relative percentage composition of Gonyaulacoids and Peridinoids of Lynx-1X well. ........................................................................................................................................ 171 Figure 5.21: Palynofacies assemblages showing POM (%) from Lynx-1X well. ................. 172 Figure 5.22: Representative photograph of palynofacies association and pie chart of PT-1 from Dzata-1 well. .......................................................................................................................... 175 Figure 5.23: APP Ternary diagram for PT-1 samples from Dzata-1 well. ............................ 176 Figure 5.24: MSP Ternary plot for PT-1 samples from Dzata-1 well. .................................. 176 Figure 5.25: Representative photograph of palynofacies association and pie chart of PT-2 from Dzata-1 well. .......................................................................................................................... 178 Figure 5.26: APP Ternary diagram for PT-2 samples from Dzata-1 well. ............................ 179 Figure 5.27: MSP Ternary plot for PT-2 samples from Dzata-1 well. .................................. 179 Figure 5.28: Representative photograph of palynofacies association and pie chart of PT-3 from Dzata-1 well. .......................................................................................................................... 181 Figure 5.29: APP Ternary diagram for PT-3 samples from Dzata-1 well. ............................ 182 Figure 5.30: MSP Ternary plot for PT-3 samples from Dzata-1 well. .................................. 182 xvi University of Ghana http://ugspace.ug.edu.gh Figure 5.31: Representative photograph of palynofacies association and pie chart of PT-4 from Dzata-1 well. .......................................................................................................................... 185 Figure 5.32: APP Ternary diagram for PT-4 samples from Dzata-1 well. ............................ 186 Figure 5.33: MSP Ternary plot for PT-4 samples from Dzata-1 well. .................................. 186 Figure 5.34: Relative percentage composition of Gonyaulacoids and Peridinoids of Dzata-1 well. ........................................................................................................................................ 187 Figure 5.35: Representative photograph of palynofacies association and pie chart of PT-5 from Dzata-1 well. .......................................................................................................................... 189 Figure 5.36: APP Ternary diagram for PT-5 samples from Dzata-1 well. ............................ 190 Figure 5.37: MSP Ternary plot for PT-5 samples from Dzata-1 well. .................................. 190 Figure 5.38: Palynofacies associations showing POM (%) from Dzata-1 well. ................... 191 Figure 5.39: Representative photograph of palynofacies association and pie chart of PT-A from Dzata-2A well. ....................................................................................................................... 194 Figure 5.40: APP Ternary diagram of studied samples from the Dzata-2A well. ................. 195 Figure 5.41: MSP Ternary plot for PT-A samples from Dzata-2A well. ............................... 195 Figure 5.42: Representative palynofacies association and pie chart of PT-B from Dzata-2A well. ........................................................................................................................................ 197 Figure 5.43: APP Ternary diagram for PT-B samples from Dzata-2A well. ......................... 198 Figure 5.44: MSP Ternary plot for PT-B samples from Dzata-2A well. ............................... 198 Figure 5.45: Representative photograph of palynofacies association and pie chart of PT-C from Dzata-2A well ........................................................................................................................ 201 Figure 5.46. APP Ternary diagram for PT-C samples from Dzata-2A well. ......................... 202 Figure 5.47: MSP Ternary plot for PT-C samples from Dzata-2A well. ............................... 202 Figure 5.48: Representative photograph of palynofacies association and pie chart of PT-D from Dzata-2A well. ....................................................................................................................... 204 Figure 5.49. APP Ternary diagram for PT-D samples from Dzata-2A well. ........................ 205 xvii University of Ghana http://ugspace.ug.edu.gh Figure 5.50: MSP Ternary plot for PT-D samples from Dzata-2A well. ............................... 205 Figure 5.51: Representative photograph of palynofacies association and pie chart of PT-E from Dzata-2A well. ....................................................................................................................... 207 Figure 5.52: APP Ternary diagram for PT-E samples from Dzata-2A well. ......................... 208 Figure 5.53: MSP Ternary plot for PT-E samples from the Dzata-2A well. ......................... 208 Figure 5.54: Representative photograph of palynofacies association and pie chart of PT-F from Dzata-2A well. ....................................................................................................................... 210 Figure 5.55. APP Ternary diagram for PT-F samples from Dzata-2A well. ......................... 211 Figure 5.56: MSP Ternary plot for PT-F samples from Dzata-2A well. ............................... 211 Figure 5.57: Relative percentage composition of Gonyaulacoids and Peridinoids of Dzata-2A well. ........................................................................................................................................ 212 Figure 5.58: Palynofacies associations showing POM (%) from Dzata-2A well. ................. 213 Figure 6.1: S2 against TOC% showing the Hydrocarbon potentiality and source efficiency 220 Figure 6.2: S2 against TOC% plot showing types of kerogens .............................................. 221 Figure 6.3: Plot of Hydrogen Index against TOC% indicating kerogen types and generation potential. ................................................................................................................................. 223 Figure 6.4: Plot of GP (S1+S2) against TOC% indicating hydrocarbon potentiality for the well samples. .................................................................................................................................. 223 Figure 6.5: Types of kerogens indicated on a modified Van Krevelen diagram ................... 226 Figure 6.6: Types of kerogen and levels of maturity shown by Hydrogen Index against Tmax ...................................................................................................................................... 226 Figure 6.7: Types of kerogen and levels of maturity shown by Hydrogen Index against Tmax ...................................................................................................................................... 227 Figure 6.8: Plot of Tmax versus Production Index showing hydrocarbon generation zone. . 229 Figure 6.9: Plot of Production Index versus Tmax showing levels of kerogen conversion and maturity .................................................................................................................................. 230 xviii University of Ghana http://ugspace.ug.edu.gh Figure 6.10: Plot of Tmax versus Vitrinite reflectance (Ro) showing maturity levels .......... 230 Figure 6.11: Plot of depths versus vitrinite reflectance data (Rcalculated) showing thermal maturity stages of Lynx-1X and Dzata-2A wells. ................................................................. 231 Figure 6.12: Vitrinite reflectance (Rcalculated) versus the Hydrogen Index (HI) showing variation of organic matter quality from Lynx-1X and Dzata-2A wells. .............................................. 232 Figure 6.13: S1 versus TOC as an indicator of indigenous and non-indigenous hydrocarbons .......................................................................................................................... 233 xix University of Ghana http://ugspace.ug.edu.gh LIST OF TABLES Table 5.1: Classification of the sedimentary organic matter. ................................................ 130 Table 5.2: Organic Matter Classification in sediments. ......................................................... 132 Table 5.3: Phytoclast and Amorphous Groups. ..................................................................... 134 Table 5.4: Major subdivisions of the Palynomorph Group. ................................................... 143 Table 5.5: Palynofacies defined on the triangle -APP with kerogen type and generation potential.. ................................................................................................................................ 146 Table 5.6: Percentage composition of palynofacies associations of particulate organic matter (POM) in Lynx-1X well. ........................................................................................................ 147 Table 5.7: Percentage composition of palynofacies associations of particulate organic matter (POM) in Dzata-1 well. .......................................................................................................... 173 Table 5.8: Percentage composition of palynofacies associations of particulate organic matter (POM) in Dzata-2A well. ....................................................................................................... 192 Table 6.1. Guidelines for interpreting source rock quantity, quality and maturation, and commonly used Rock-Eval parameters. ................................................................................ 217 xx University of Ghana http://ugspace.ug.edu.gh CHAPTER ONE INTRODUCTION 1.1 BACKGROUND Ghana, in the last ten (10), years has made significant new hydrocarbon discoveries (mostly crude oil) which have been documented offshore in the Tano Basin in western Ghana, the current most important oil-producing area in Ghana. In 2010, Ghana started production of crude oil in commercial quantities from the Jubilee oil field with proposed production of 55,000 barrels per day. In 2018, Ghana National Petroleum Corporation (GNPC) continued to manage its interests in various petroleum licenses in Ghana’s sedimentary basins specifically in the Tano basin and together with its upstream partners continued the production of crude oil and gas from the three producing fields (Greater Jubilee, Tweneboa-Enyenra-Ntomme (TEN) and Sankofa-Gye-Nyame (SGN)). Cumulative crude oil production achieved from the three producing fields totalled 46,024,211 million barrels from January to September 2018, translating into an average daily oil production of 196,177 barrels (Annual report on the petroleum funds, Ministry of Finance, 2018). The Cretaceous source rocks have proved to be the most prolific oil and gas producing horizons in the Tano basin. The future of the Ghanaian oil and gas industry within the basin needs a holistic detailed study of both shallow and deep-water oil blocks. However, sediments within the deep-water settings have not been subjected to detailed biostratigraphic study or lithostratigraphic correlation. There is therefore the need for detailed biostratigraphic and lithostratigraphic correlations study as GNPC embarks on detailed geological and geophysical study on the Tano basin and other sedimentary basins in Ghana. 1 University of Ghana http://ugspace.ug.edu.gh 1.2 PROBLEM STATEMENT AND JUSTIFICATION In the petroleum exploration history of Ghana, seismic data acquisition, processing and interpretation by GNPC and their partners in the Tano Basin have received tremendous attention. Seismic data analysis over the last decades have made tremendous improvements which have led to the discovery of numerous giant oil reservoirs in petroleum provinces around the world. The science of petroleum exploration and production is multi-tool based with each tool complementing the other. Comprehensive palaeontological and palynofacies analyses are rarely performed during petroleum exploration and only surfaces are picked for age assignment using index fossils. Biostratigraphy (e.g. palynology) is one of the most important tools used in petroleum exploration essentially as a stratigraphic tool in depositional settings such as continental, coastal and marginal marine environments. When integrated with other tools including wireline logs and seismic stratigraphy, it is useful mainly for chronostratigraphic correlation, palaeoenvironmental studies, evaluation of source, reservoir and sealing rocks (Copestake, 1993). For true representation of the subsurface by seismic and Sequence stratigraphy, there is the need of integrating tools such as well logs, biostratigraphy and geochemistry to be able to interpret seismic sections to provide information on facies, lithologies, stratigraphic ages, palaeowater depths, palaeoclimate, and palaeoenvironment. Subsurface informative tools and techniques such as palynology and palynofacies are utilized to subdivide and correlate subsurface sedimentary sediments and in combination with organic geochemistry data, it is used to evaluate the hydrocarbon potential of basin. Regardless of the effectiveness of palynology as an important tool in sequence stratigraphic analysis and resolution, it is still being grossly under-utilized in petroleum exploration and production in Ghana partly due to how young the industry is. This project seeks to specifically investigate the Deep-Water Cape Three Points (DWCTP) block offshore Tano basin which was acquired by ExxonMobil Exploration and Production Ghana, in January 2018. 2 University of Ghana http://ugspace.ug.edu.gh The PhD thesis seeks to study samples from three oil/gas wells out of the four wells within the DWCTP oil block which would provide detailed biostratigraphic interpretations based on palynology, depositional environments based on palynofacies analysis and evaluate the hydrocarbon potential based on palynofacies and rock eval pyrolysis data analysis. This would provide significant contributions to fully explore the basin and form basis for further studies in the basin and other sedimentary basins of interest in Ghana. 1.3 AIMS AND OBJECTIVES OF STUDY This research aims for the following: 1. Provide independent age control for the studied intervals by means of palynological studies. 2. Interpret paleoenvironmental and paleoclimatic conditions at the time of deposition and the probable hydrocarbon product using palynofacies analysis. 3. To evaluate the organic richness and hydrocarbon potential of source rocks. The objectives of this project carried out were as follows: 1. Standard acid maceration palynological preparation techniques were applied to studied samples to extract palynomorphs for biostratigraphic and other investigations. 2. Identification of all stratigraphically significant recorded taxa present in each well in order to establish a biostratigraphy for each of the three well successions. 3. The paleoenvironmental settings prevailing during the deposition of the studied sections were determined through study of the palynomorphs and palynofacies analyses. 4. Source rock analyses were used to determine source rocks potential for hydrocarbon generation, in addition to the determination of the different kerogen types in order to evaluate the hydrocarbon potential and quality of source rocks. 3 University of Ghana http://ugspace.ug.edu.gh 1.3.1 General overview of the geology of Ghana. Ghana, based on age data, tectonics and lithology, can be divided into five main geological domains (Attoh et al, 1997) (Fig. 1.1): A. The western Units found at the eastern margin of the West African Craton (Birimian and Tarkwaian). B. The Precambrian mobile belt units found at south-eastern part of the country (the Dahomeyide: - the Dahomeyan, the Togo and the Buem). C. The Voltaian sediments at the central part of the country (the largest sedimentary terrain). D. The Coastal sedimentary basins. E. Tertiary to Recent deposits. 1.3.1.1 The Western units The western part of Ghana is characterized by supra crustal rocks of Paleoproterozoic ages, which can be sub-divided into the Birimian and Tarkwaian. The Birimian rocks comprise an assemblage of sedimentary/volcaniclastic rocks which separate a series of subparallel, roughly equal-spaced northeast trending volcanic belts of volcanic rocks. The sedimentary/volcaniclastic rocks were considered to be the lower members of the Birimian whereas the upper members consist of the volcanic belts, mainly metamorphosed basic and intermediate lavas and pyroclastic rocks (Junner, 1935). The lower Birimian rocks comprise an assemblage of fine-grained rocks with a large volcano clastic component. Typical lithologies include tuff, calcareous shale, phyllite, siltstone, greywacke and some chemical (Mn-rich) sediment. The upper Birimian rocks comprise mostly basalts with some interflow sediment (Eisenlohr and Hirdes, 1992). However, recent studies, have shown that the volcanics 4 University of Ghana http://ugspace.ug.edu.gh and the sedimentary rocks were deposited contemporaneously as lateral facies equivalents (Leube et al., 1990). The Birimian is intruded by different generations of granitoids. Overlying the Birimian unit in a synclinal basin is the Tarkwaian unit of rocks (e.g., Junner et al., 1942; Kesse, 1985). The Tarkwaian rocks consists mainly of coarse clastic sediments, subdivided into four major units: (i) the Kawere Group, (ii) Banket Series, (iii) Tarkwa Phyllite, and (iv) Huni Sandstone (Junner et al., 1942; Kesse 1985). The basal Kawere Group consists of the units of sandstones, and polymictic, poorly sorted, large-pebble conglomerates and argillites. The Banket Series is mainly made up of sandstones and conglomerates with minor grits, breccias and argillites. The Tarkwa Phyllite is mainly made up of finely laminated and graded argillite with interbedded green sandstone, which is conformably overlain by the Huni Sandstone. The Huni sandstone consists of fine-grained green sandstone with thin, intercalated argillite layers. 5 University of Ghana http://ugspace.ug.edu.gh Figure 1.1. Simplified geological map of Ghana. 1.3.1.2 The Pan-African Dahomeyide Belt The Dahomeyide orogeny of West Africa is a Pan African belt between the passive continental margin of the West African Craton (WAC) which is postulated to have resulted from the easterly subduction of the rifted margin of WAC (Affaton et al., 1991; Attoh and Nude, 2008) and the Saharan Meta Craton (SMC) and resulted in the assembly of northwest Gondwana (Hoffman, 1991). The Dahomeyide belt in Ghana is about 600Ma, exposed in the south-eastern 6 University of Ghana http://ugspace.ug.edu.gh part of the country and represents the southern extension of the Trans-Saharan mobile belt (Nude and Attoh, 2008). These rock units are also found in some parts of Benin and Togo. Its northern extension forms the Adrar des Iforas of Mali, the Gourma of Burkina Faso and Mali and the Western Hogger in Algeria which lies on the eastern margin of the West African Craton (Cordani et al., 2003, Tohen et al., 2006). The Dahomeyide of Ghana (Fig.1.2), based on litho-tectonic unit and age can be subdivided into three structural units (Kesse, 1985). These include: 1. Buem structural units 2. Togo structural units 3. Dahomeyan structural units Stratigraphically, the Dahomeyan forms the basement unit and is overlain by the Togo and Buem respectively. Due to thrust faulting, the Togo overlies the Buem as certain places and seen to be overlain by the Dahomeyan at some other places. 1.3.1.3 The Voltaian The Voltaian which occupies a surface area of ~115,000 km² in Ghana as well as smaller areas in Togo, Burkina Faso, Niger and Benin consist of Neoproterozoic to early Paleozoic strata (Kalsbeek et al., 2008). The Voltaian (Fig. 1.3) is up to ~ 6 km thick succession of sandstones and mudstones with subordinate proportions of limestone (Junner and Hirdes, 1946; Bozhko, 1969; Affaton et al., 1980; Affaton, 1990). According to Leprun and Trompette, 1969; Sougy, 1971; Affaton (1975, 1990, 2008), the Voltaian is characterized by three surpergroups: (1) The Kwahu/Kintampo/Damongo/Gambaga/Bombouaka Supergroup, (2) the Oti/Afram/ Pendjari Supergroup, and (3) the Tamale Supergroup. 7 University of Ghana http://ugspace.ug.edu.gh Figure 1.2: Map of the Dahomeyide orogen in southeastern Ghana and adjoining part of Togo (After Attoh, 1990). These supergroups represent clearly different stratigraphic divisions than the lower, middle, and upper Voltaian subdivisions previously used in Ghana. Moreover, they consider the Volta basin as a composite basin, comprising a passive margin and a typical foreland basin (Geotect, 2009). 8 University of Ghana http://ugspace.ug.edu.gh Figure 1.3. Geological map of the Dahomeyide belt showing the Voltaian Supergroup (after Duclaux et al., 2006). 1.3.1.4 The Coastal Sediments The crustal evolution of Ghana in the Phanerozoic era was characterized by development of a series of spatially restricted shallow, mostly marine coastal basins along the present-day Ghanaian coast. Sedimentation began in the Ordovician (Sekondian Group), to the Devonian 9 University of Ghana http://ugspace.ug.edu.gh (Accraian Group) to Upper Jurassic-Lower Cretaceous (Amissian Group) to Cretaceous (Apollonian Group) to the Tertiary and Quaternary (Kesse, 1985). 1.4 STUDY AREA Selected cutting samples of rocks for this thesis was collected from three wells in the Deepwater Cape Three Points (DWCTP) Block offshore Tano basin, western Ghana, namely; Lynx-1X, Dzata-1 and Dzata-2A (Fig. 1.4). Samples were provided by the Core Laboratory of the Ghana National Petroleum Corporation (GNPC). Figure 1.4: Map of Study area showing studied wells Offshore Tano Basin (Lynx-1, Dzata-1 and Dzata-2A). 1.5 GEOLOGY AND TECTONICS OF THE TANO BASIN The Tano basin is located between the mouths of the Ankobra River in the east and the Tano River in the west (96 km). It is East-West onshore-offshore structural basin (Davies, 1986) occupying an area of about 3000 square kilometers offshore with an estimation onshore 10 University of Ghana http://ugspace.ug.edu.gh constituent to be approximately 1165 km2 (Kesse, 1985). The Gulf of Guinea Province as defined by the U.S. Geological Survey (USGS) consists of the coastal and offshore areas of Côte d’Ivoire, Ghana, Togo, and Benin, and the western part of the coast of Nigeria, from the Liberian border east to the west edge of the Niger Delta. The province includes the Ivory Coast, Tano, Saltpond, Keta, and Benin Basins and the Dahomey Embayment. The Tano basin includes the narrow Mesozoic coastal strip of southwestern Ghana, the continental shelf, and steep submarine Ivory Coast-Ghana ridge which form the continental slope (Mah, 1987). The Tano Basin formed because of a complex series of pull apart and transforms movements which accompanied the opening of the South Atlantic Ocean due to the separation of the South American and African continents. Kesse (1985) described the Tano Basin as being a portion of the crescent shaped basin along the coast of the Atlantic Ocean. The St. Paul transform fault zone to the east and the Romanche transform fault zone to west mark the boundaries of the Tano basin (Fig. 1.5). Rocks of the Tano Basin are part of the Apollonian System of Cretaceous age and consist mainly of limestones with alternating clays and sands (Kitson, 1928) and Junner (1940) in Cox (1952) articulated that, the limestones are fossiliferous and are inter bedded with clay and formed a continuous crest rising from the beach near the village of Kangan and run in a north- westward direction through a point one-and-a-half-mile north of Nauli and to the Tano river north of Edu. The Precambrian metasedimentary rocks of the Birimian supergroup form the basement rocks of the Apollonian rocks. These metasedimentary rocks are mostly schist, phyllite and greywacke. 11 University of Ghana http://ugspace.ug.edu.gh Figure.1.5 Tano Basin within the St. Paul and Romanche transform fault zones (after Brownfield and Charpentier, 2006). The Tano Basin is underlain by Eocene and Cretaceous sediments and is the focus for deposition of a thick Upper Cretaceous, deep water clastic sequence which, in combination with a different Tertiary section, provided enough thickness to mature an early-mid Cretaceous source rock in the central part of the Tano basin. This distinct reservoir resulted in the formation of combination trapping geometries that create the Jubilee accumulations, and along which several other prospects are located. The early Albian tectonism resulted in the formation of the North Tano fault bounded by tilted structural block which are termed ‘structural highs’ in the Tano Sub-basin that influenced and controlled some of the sediment deposition in the basin 12 University of Ghana http://ugspace.ug.edu.gh whereas the creation of the South Tano Structural trend, faulting, uplift and erosion along the outer margin of the Tano basin resulted from the final separation of the West Africa and Northern Brazilian continental plates (Davies, 1989). The South Tano High creates focus of migration, concentrating oil generated in a large kitchen where the Jubilee fan drapes over high, on top of source rock and focuses charge up-dip. Onshore of the Tano basin, is predominantly clays, sands and limestone with a general SSW dip direction and low dip angles. However, at depth, these sands and clays compact to form sandstones and shales. The limestones are extremely fossiliferous and are overlain by recent to Tertiary deposits of sands, clays and laterite. As per Guiraud et al. (1997), three lithofacies creates the CIG sedimentary wedge which are yellowish siltstones, dark clays and interbedded greenish sandstone with grey coarse sandstones and micro conglomerates. Early Cretaceous age in a shallow marine deltaic environment of deposition was inferred for these synrift sediments. The Tano Basin lies within the West African Transform Margin. Seismic surveys of the Ocean Drilling Programme (ODP) have shown that this margin has a distinctive feature of a NE-SW trending marginal ridge about 130 km long (Atta-Peters and Salami, 2004). This transform margin is associated with the (CIG) continental disintegration of the South America and Africa. The ridge within the CIG is bounded to the north by the deep Ivorian Rift Basin (Atta-Peters and Salami, 2004). Larmache et al., (1997) indicated that the ridge has a sedimentary sequence which bears a close resemblance with the syn-rift sediments of the Ivorian Basin. The basin accumulated thick Upper Cretaceous, deepwater clastic succession in combination with a Tertiary section, gave adequate thickness to mature an early to mid-Cretaceous source rock in the focal part of the Tano Basin. This reservoir and charge fairway formed the play which, when draped over the large plunging South Tano high resulted in the formation of 13 University of Ghana http://ugspace.ug.edu.gh numerous trapping geometries that resulted in the Jubilee and Odum accumulations, and alongside different prospects (Daily et al., unpublished). The three main tectonic phases of the Tano Basin are as follows: • Pre-Rift represented by Precambrian to late Jurassic rocks. • Syn-Rift phase with sediments of early Cretaceous age. The end of the syn-rift stage is delineated by a major unconformity which separates it from the marine post-transform rocks of the uppermost Albian and Cenomanian. • Post-Rift phase of marine Cenomanian to present day. Davies (1989) reported that “movement along a series of transform faults including major east- west oceanic transform faults in the Romanche Fault Zone and the St. Paul fracture zone during the continental separation led to the development of the large rift basin in the Tano area of Ghana”. These movements brought about the formation of the rift basin around the Aptian- Early Albian time. Davies (1989) suggested the separation of the continents to have occurred in the late Albian. 1.6 STRATIGRAPHY OF THE TANO BASIN GNPC (2004) describes the stratigraphy of the Tano Basin from the lower sections to the upper sections as represented below (Fig. 1.6): 1.6.1 Lower Cretaceous Section 1.6.1.1 Lower Albian (Kobnaswaso Formation) The lower Albian rocks are called the Kobnaswaso Formation and comprises mainly sandstones and shales. The basement of this interval has never been penetrated even though deepest well drilled here is 4,270 m deep. Age proposed for these sediments is lower 14 University of Ghana http://ugspace.ug.edu.gh Cretaceous (Albian) to Jurassic. There is evidence for two distinct megasequences within parts of the South Tano area. The lower part of the Kobnaswaso Formation consists of dark grey to green shales with occasional beds of very fine sandstone and siltstone. According to Davies (1989), the upper megasequence on top of these shales is a series of upward coarsening sequences, often referred to as parasequences. There are also intrusives of Jurassic age that mark the onset of rifting in the Gulf of Guinea. Regional seismic surveys indicate thick and different sedimentary wedges within the Kobnaswaso interval which is a characteristic of rift basin deposits. The extremely thick sandstones which are characteristic of the Kobnaswaso sequence in the North Tano and onshore wells provide excellent potential reservoirs over this entire area. 1.6.1.2 B-Shale (Bonyere Formation) This formation is 200 m thick and the most important strata within the Tano Basin because it can be correlated throughout the whole basin. B-Shale is a medium to dark grey, blocky, micromicaceous shale with a few siltstone and sandstone interbeds. The age of the B-Shale is inferred to be middle Albian (Davies 1989). The B-Shale is considered to record the first major marine transgression into the Tano Basin (Davies, 1989). These transgressive shales overlie the Kobnaswaso unconformably and provide a good seal and possibly, source rock of hydrocarbons within the Tano Basin (Khan, 1970). 1.6.1.3 Middle to Upper Albian These are shallow marine deposits that mainly comprises of sandstones, shales and a little of limestones. These sediments presumably represent early breakup (transitional stage) deposits. In the South Tano area this interval comprises approximately 600 m of thick coarsening upward units which provide numerous thick reservoir sandstones. The mid Albian deposits are of a 15 University of Ghana http://ugspace.ug.edu.gh lacustrine depositional environment and are large source rocks for gas in North Tano Basin. A regional mid-Albian unconformity divides the mid-Albian interval into upper and lower sedimentary packages. An angular unconformity overlying tilted fault blocks is observed in the South Tano area. In the North Tano area, the mid-Albian unconformity is overlain by dark grey transgressive shales which truncates and seals the underlying Kobnaswaso sandstones. The Cenomanian strata represent a period of local shallow water shoaling which preceded the major transgressions of the Late Cretaceous and Tertiary times. 1.6.2 The Upper Cretaceous Section 1.6.2.1 Cenomanian Limestone The upper Cenomanian section consists of the thickest limestone accumulations in the area interbedded with several shales, claystones, siltstone and fine sandstone beds. It is the most prominent reflector on the seismic data and appears to be laterally continuous across the area, found in every South Tano well. The limestone is partly mottled, slightly argillaceous and chalky. Although laterally continuous, this Cenomanian section does vary quite considerably in thickness (RRI, 1998; Davis, 1986). The Upper Cretaceous to recent sediments comprises of an offshore dipping sedimentary wedge which thickens from 1,500 m in the North Tano area to approximately 3,700 m offshore at South Dixcove. 1.6.2.2 Turonian to Upper Santonian The Turonian to Upper Santonian section comprises medium brownish-grey shales and claystones, with occasional dolomite or limestone. It is generally thick, about 920 ft (280 m). The rate of deposition in this succession of fine-grained sediments was high, approximately 167 ft (51 m) per million years; which could only have taken place in a rapidly subsiding basin. 16 University of Ghana http://ugspace.ug.edu.gh Most deepwater reservoirs of commercial importance are in the Turonian (Jubilee, Tweneboa, etc.). The Turonian also contains a significant portion of the source rock responsible for the Jubilee Field oil. 1.6.2.3 Campanian The Campanian interval averages over 900 ft (276 m) over the South Tano area. This thick succession is known to have formed under conditions of rapid subsidence and was laid down in a relatively short period of time. This interval is shale-rich with occasional stringers of dolomite and limestone. In the deepwater area fields such as Teak, Odum have Campanian reservoirs. 1.6.2.4 Maastrichtian The Maastrichtian section is relatively thin in comparison to the rest of the Upper Cretaceous sections. This interval is an indicator that during the late stages of the Upper Cretaceous, subsidence slowed. It is described as principally claystone with occasional sandstone and dolomite beds with the upper parts having significant fossils (Davies, 1986). The thick, highly porous Maastrichtian sandstones are of great interest. Although the Maastrichtian section appears to lie above the oil maturation window, numerous oil shows have been reported from these sandstones. It may be that either oil has migrated upward through faults into the Maastrichtian, or oil has been generated at very low maturation levels, or thirdly, that Maastrichtian sediments may be found in oil mature deep basinal areas that flank the southwest and northeast sides of the North Tano high. 17 University of Ghana http://ugspace.ug.edu.gh 1.6.3 The Tertiary Section 1.6.3.1 Paleocene, Eocene, Oligocene and Miocene “The Middle and lower Eocene stratigraphic section consists of finely laminated dark grey/brown claystones with thin beds of fossiliferous dolomite and fine sandstone. Large portions of the Paleocene, Upper Eocene and Oligocene section are either only present as a thin bed or completely absent and attributed to extensive uplift and erosion associated with the Alpine Orogeny” (GNPC, 1998). In the south-eastern part of the area, seismic data show the presence of a number of Oligocene to Miocene submarine channels that have removed large amounts of the Eocene section. Miocene sedimentary rocks which were found are described as predominantly brown-grey coloured claystones, highly fossiliferous, glauconitic and sandy in part with stringers of dolomitic limestone. Unconsolidated marine sands with shell fragments and some clays grading to claystones and siltstones dominate the Middle Miocene to Recent section. 1.7 PETROLEUM EXPLORATION AND EXPLOITATION HISTORY IN THE TANO BASIN. Searching for oil and gas in Ghana officially started in 1896 in the Tano area. Earlier explorationists discovered seepages of oil in the Tano areas which initiated the exploration for hydrocarbons in Ghana formerly called the Gold Coast. The West Africa Oil and Fuel Company drilled wells between 1896 and 1903 (WAOFCO-1, 2, 3, 4 & 5). WAOFCO-2, the second well on the Takinta concession with a total depth of 35 m, was the first documented discovery well in the country, producing 5 bopd between 1896 and 1897. In the early part of the twentieth century, there was an influx of international oil companies on the shores of Ghana from 1909-1925. Between 1909 and 1913 the French oil 18 University of Ghana http://ugspace.ug.edu.gh company, Societe Francaise de Petrole (SFP) drilled a total of six onshore wells (SFP-1, 2, 3, 4, 5, & 6). SFP-1 struck oil at 10-17 m depth and produced 7 bopd. The wells SFP-3, 4, 5 & 6 all had very good oil indications and/or flowed at relatively shallow horizons, according to available records. Two wells were drilled by African and Eastern Trade Corporation (AETC) and named AETC-1&2 in onshore Tano between 1923 and 1925, progressively encountering heavy oil, light oil and gas at various depths. Figure 1.6. The General Stratigraphy of the Tano Basin (After GNPC, 2004). 19 University of Ghana http://ugspace.ug.edu.gh After a period of inactivity in exploration in Ghana which lasted for almost 30years, Gulf Oil Company acquired the onshore Tano license and drilled four (4) wells at Bonyere, Epunsa, and Kobnaswaso from 1956 to 1957. Apart from well logs, there is very little information on these wells as the wells were drilled without the help of seismic data. From 1896 to 1957 a period of 61 years, 17 onshore wells had been drilled in the Onshore Tano basin. Phillips Petroleum appraised the South Tano discovery in 1979 and made gas and condensate discovery on the satellite 1S-3AX structure down dip of the main field. They went ahead to further appraise the South Tano find by drilling IS-4X in 1981 and later declared the South Tano discovery sub-commercial and finally relinquished the block. Geophysical Services Incorporated (GSI) in 1982 entered into a Petroleum Agreement with the then Ministry of Fuel and Power to acquire a Non-Exclusive 2D seismic survey to accelerate the exploration and production of hydrocarbons offshore Ghana. The data was acquired in late 1982 to 1983 and covered the area from the Eastern border of Ghana to Cape Three Points. The Canadian government, acting through Petro Canada International Assistance Corporation (P.C.I.A.C), expended considerable funds to support GNPC in acquiring extensive 2D seismic data in the offshore Tano/Cape Three Points Basin in 1984 (PCIAC-84 -97, 98 & 99 vintages). P.C.I.A.C also funded the drilling of two appraisal wells (ST-5) and ST-6) over the Tano field and the drilling of shallow wells in the Onshore Tano Basin. The Government of Japan in a bilateral cooperation also assisted the Government of Ghana by acquiring offshore 2D seismic data for GNPC in 1987. This data covered the area from the Eastern border of Ghana to Cape Three Points and it was an infill to the 1982/83 GSI Speculative Survey. GNPC in 1989 funded the acquisition, processing and interpretation of first 3D seismic over the South Tano Field. Following interpretation of the 3D seismic data and subsequent commissioned studies to determine the viability of the Integrated Tano Fields 20 University of Ghana http://ugspace.ug.edu.gh Development Project to use the gas for power generation, GNPC drilled three wells over the South Tano Field in 1994 using its acquired drillship (Discoverer 511) and three other rigs in addition to other infrastructure to help facilitate rapid development of the Tano Fields. As part of the integrated Tano Fields development project, GNPC ordered a power barge to utilize the anticipated gas from the Tano Fields. The infrastructure for the power generation barge was built at Effasu-Mangyea and power transmission lines to link the national grid in the Jomoro district in the Western Region to Essiama and Elubo with funds that GNPC had secured. From 2001-2007, commercial exploration for hydrocarbons intensified with some independent Oil Companies such as Kosmos Energy, Hess Corporation and Tullow Oil, acquiring exploration and production rights over areas in deep water. There was a shift of focus from shallow water to deepwater areas which was occasioned by other deepwater discoveries made in the region and by the results of four deepwater wells drilled in Ghana between 1999 and 2003. These wells proved the existence of an active petroleum system in the deepwater, a fact which hitherto was unknown. Hunt Oil’s WCTP-2X well encountered 14 ft of light oil column. This effectively reduced the risk of petroleum generation in the deepwater areas of Ghana. Kosmos Energy (block operator), Anadarko (technical operator), Tullow Oil and E. O. Group struck a significant (about 312 ft net) column of high-grade oil in the Mahogany prospect with the Mahogany-1 well in the West Cape Three Points Licence. This is the most significant discovery crowning years of concerted effort by all. From August 2007 to 2013, 23 discoveries (Odum, Ebony, Tweneboa, Sankofa, Dzata, Owo, Teak-1, Paradise-1, Banda-1, Gye Nyame, etc.) have been made. Except Ebony, all recent discoveries were made in deepwater (water depths ranging from 800 to 1600 m). The Mahogany and Hyedua discoveries have been appraised and put into production as Jubilee Field (Petroleum Commission of Ghana, n.d.). 21 University of Ghana http://ugspace.ug.edu.gh CHAPTER TWO LITERATURE REVIEW 2.1 PREVIOUS PALYNOLOGICAL WORK IN THE STUDY AREA. Earlier recorded palynological study in the region was in the Cretaceous-Paleocene from the Côte D’Ivoire-Ghana transform margin, sites 959, 960, 961, and 962 by Mascle et al. (1998) as part of the proceedings of the Ocean Drilling Programme. Total of 204 Cretaceous and Paleocene samples from Holes 959D, 960A, 960C, 961A, 961B, 962B, 962C (barren), and 962D of the Côte d’Ivoire-Ghana Transform Margin (Leg 159) were analyzed and revealed three main palynofacies types. “The first type indicates strong terrestrial depositional conditions and characterizes lithologic Unit V of Hole 959D, Subunit VB and most samples of Subunit VA of Hole 960A, and Unit III of Holes 961A and 961B” (Mascle et al., 1998). Stratigraphically significant spores and pollen grains present indicated a late Barremian-middle Albian age for Unit V of Holes 959D and 960A, and a middle Albian age for Unit III of Holes 961A and 961B. Palynofacies type two revealed mixed terrestrial and marine depositional conditions. “This type was observed in Subunit IIC of Hole 962B and Unit III of Hole 962D”. Stratigraphically significant spore, pollen grain, and dinoflagellate cyst species suggested a Cenomanian age for these units in Holes 962B and 962C. Palynofacies type three represented clearly marine environmental conditions which was found in Subunit IVA and Unit III of Hole 959D, which were of highly diversified dinocyst assemblages (Mascle et al., 1998). They inferred that Subunit IVA and the lowermost cores of Unit III were probably early Coniacian in age; subsequent cores of Unit III are Santonian, Campanian, Maastrichtian, Danian and at the top, Late Thanetian in age. 22 University of Ghana http://ugspace.ug.edu.gh Atta-Peters and Salami (2004) recovered miospores dominated by angiospermic pollen with trilete and monolete pteridophytic spores from the ST-8 well, offshore Tano Basin. The monosulcate pollen recovered were Spinizonocolpites, Proxapertites, Longapertites and Mauritiides of late Cretaceous and Lower Tertiary pollen assemblage, which fit well into the palmae and belong to the tropical-subtropical Senonian Palmae Province of Africa, South America and India (Herngreen and Chlonova, 1981) which suggest a mangrove environment of warm and humid climate (Atta- Peters and Salami, 2004). Atta-Peters and Salami (2006) recovered Cretaceous dinoflagellate cysts and miospores from the Tano 1-1 and 1S-3AX wells in Ghana. Based on maker palynomorphs recovered from the Tano 1-1 well, an Aptian-early Cenomanian age has been assigned to the sediments of this well. The palynomorphs observed were elements of the Albian-Cenomanian Elaterate Province and suggested a warm tropical climate. From the well 1S-3AX, Atta-Peters and Salami (2006) recovered the palynomorphs Auriculiidites reticulatus, Spinizonocolpites echinatus, Buttinia andreevi, Longapertites spp., and Echitriporites trianguliformis, which are typical elements for the Campanian-Maastrichtian. These palynomorphs fit into the late Cretaceous Senonian Palmae Province which also supports a warm tropical climate. Atta-Peters et al. (2012) identified five palynofacies assemblages (I-V) based on the percentage relative abundances of the sedimentary organic matter from the Bonwire-1 well, Tano basin western Ghana. The revealed palynofacies reflected brackish, distal dysoxic-anoxic shelf, proximal dysoxic-suboxic, fluvio-deltaic/nearshore environments with high oxygen levels and low preservation rates respectively. Atta-Peters (2013) worked on the elater bearing forms from the 1S-3AX well with sediments being assigned Albian-Cenomanian age based on the palynomorph assemblage and further suggested an arid to semi-arid paleo-climatic condition existing at the time of deposition based 23 University of Ghana http://ugspace.ug.edu.gh on recorded species and inferred that the elaterates were deposited in a fluvial/lacustrine environment and went extinct after the Cenomanian because of the sudden shift to a more open marine environment. Data recovered by Atta-Peters and Kyorku (2013) assigned an Aptian to Cenomanian age based on recovered marker palynomorphs (Afropollis jardinus, Ephedripites spp, Elaterspores etc.) from palynofacies analysis carried out on fifty-eight (58) cutting samples from the Dixcove 4- 2X well offshore Cape Three Points in the South Tano Basin. Atta-Peters and Kyorku (2013) identified five palynofacies types (P-I to P-V) with P-I and P-IV suggesting proximity to a fluvio-deltaic source in a moderately dysoxic environment, P-II reflecting a proximal (pro delta) dysoxic - suboxic environment, P-III being indicative of deposition in an oxidizing condition in proximity to terrestrial sources and P-V being attributed to deposition resulting from high preservation rate and low energy dysoxic- anoxic condition in marginal marine environment. Atta -Peters et al. (2015) established five palynofacies associations (I-V) from samples of the ST-7H well, Offshore Tano basin, based on the percentage relative abundances of the sedimentary organic matter. Based on marker palynomorphs, Atta-Peters et al. (2015) identified an Aptian to Maastrichtian age for the sediments of the ST-7H well, with an unconformity between the Cenomanian and Campanian sediments. Atta-Peters and Achaegakwo (2016) observed the presence of Afropollis, Classopollis, Ephedripites, elaterate pollen and pteridophytic fern spores from the sediments from the Epunsa-1 well, Onshore Tano basin. This assemblage suggested a paleoenvironment with parent plants inhabiting moist biotopes or wetlands in a humid, warm coastal plain in a semi- arid/arid climate. Based on biostratigraphically important elaterate pollen and associated taxa, they suggested an Albian-Cenomanian age for the sediments of the Epunsa-1 well succession. 24 University of Ghana http://ugspace.ug.edu.gh Atta-Peters and Achaegakwo (2016) also adopted visual kerogen analysis and spore colour for the evaluation of hydrocarbon potential and thermal maturation respectively and suggested a mature oil prone to immature gas prone source rock in the Epunsa-1 well. Achaegakwo and Atta-Peters (2021) carried out palynofacies analysis on 43 samples from the ST-9H well in the Tano Basin, with the aim of reconstructing the palaeoenvironment of the Upper Cretaceous sediments in the well. Their study defined four palynofacies units (PA-PD) which reflected a deposition in near shore/shallow marine (inner neritic) environment under distal dysoxic-anoxic shelf condition, an inner-middle neritic environment under mud- dominated oxic shelf conditions, an open marine (outer neritic) environment under distal suboxic-anoxic basin conditions, and in a proximal-marginal marine environment under dysoxic-anoxic basin conditions. Achaegakwo and Atta-Peters (2021) recovered species that supported a Campanian- Maastrichtian age. The dinocysts contents recovered include Dinogymnium euclaensis, D. longicornis, D. denticulatum, Cyclonephelium vannophorum, Oligosphaeridium complex, Cordosphaeridium inodes, Spiniferites ramosus, Andalusiella polymorpha, A. mauthei, A. rhomboides, Adnatosphaeridium multispinosum, Palaeocystodinium australinium, P. golzowense, Cerodinium obliquipes, C. boloniense, C. diebelli, Senegalinuim bicavatum, S. laevigatum, Phleodinium magnificum, P. tricuspis, Subtilisphaera sp., Xenascus ceratioides, Trichodinium castanea, Glaphyrocysta sp., and Odontochitina porifera. Stratigraphic miospores they recorded from the well and used to support the Campanian-Maastrichtian age include abundant occurrences of Auriculiidites sp., Proteacidites dehanni, Echimonocolpites sp., Spinizonocolpites echinatus, S. baculatus, Buttinia andreevi, Zlivisporis blanenesis, Retitricolpites sp., Echitriporites trianguliformis, Longapertites marginatus, L. 25 University of Ghana http://ugspace.ug.edu.gh vaneendenburgi, Proxapertites cursus, P. operculatus, Mauriitidites crassibaculatus, and Foveotriletes margaritae. 2.2 PREVIOUS SOURCE ROCK EVALUATION AND HYDROCARBON POTENTIAL OF THE TANO BASIN. Sediments from three exploratory oil wells (ST-9H, WCTP-2X and WT-1X) from the Tano Basin, south-western Ghana were evaluated for their hydrocarbon generation potential by using geochemical data (TOC, Rock-Eval pyrolysis data) by Atta-Peters and Garrey (2014). The total organic carbon (TOC) contents of samples of these wells ranges from fair to good which indicated that conditions exist in the Basin that was favourable for organic matter production and preservation. Atta-Peters and Garrey (2014) further stated that sediments from oil wells (ST-9H, WCTP-2X and WT-1X) kerogen types variations were attributed to the relative stratigraphic positions of the outcrops within the basin and that the samples represented sufficient organic matter contents to produce oil and gas. ST-9H well yielded kerogen types II, IV and III whereas wells WCTP-2X and WT-1X was identified with kerogen types III and II. Atta-Peters et al. (2015) performed a source rock evaluation on samples from ST-7H well offshore Tano basin in the western region of Ghana and geochemical data indicated that the samples from ST-7H well had fair to very good petroleum potential and most of the samples were out of the hydrocarbon generating zone due to the low (< 0.10) Production Index (PI)”. Atta-Peters et al. (2015) revealed that, the kerogen types shown for the samples in ST-7H well were of type II, II/III and III which are oil prone, oil-gas prone and gas prone respectively. Thermal maturity of samples within ST-7H well indicated immature to early mature hydrocarbons. 26 University of Ghana http://ugspace.ug.edu.gh Atta-Peters et al. (2016) studied 66 cuttings for source - rock potential of the lower cretaceous sediments in SD-1X well, offshore Tano basin, southwestern Ghana and inferred that the source rocks are of good to excellent organic matter with TOC values between 0.69-8.58 wt. % (average of 2.39 wt. %) which suggested that there might exist conditions in the basin that favour organic matter production and preservation. Atta-Peters et al. (2016) further stated that the thermal maturity of samples had Tmax values of 342-450℃ (average of 427℃), with majority of them indicating moderately immature to early mature source rocks, with good to excellent organic richness. “The organic matter contained in the samples with S2 values of 0.2- 44.39 (average 6.28 mg HC/g rock) indicated good to very good source rock of kerogen types II, II/III and III which are oil prone, oil-gas prone and gas prone respectively. The production index (PI) of between 0.02-0.53 (0.11) of SD-1X well indicates that most of the samples are indigenous hydrocarbons and with low levels of contamination. 27 University of Ghana http://ugspace.ug.edu.gh CHAPTER THREE MATERIALS AND METHODS 3.1 MATERIALS 3.1.1 The Lynx-1X well Lynx-1X well is an exploratory oil well drilled in the year 2014 in the Deep-water Cape Three (DWCTP) block offshore Tano Basin which was operated by LukOil Overseas Ghana Ltd. It is represented by 140 well samples. Lynx-1X well is located geographically on these coordinates; Latitude 4° 04′ 52.8878″ N, and Longitude 2° 13′ 52.4221″ W (Fig. 1.4) and attained a total depth of 5300 m. End of well reports gives details of various lithologies below (GNPC, unpublished) (Fig 3.1). 3.1.1.1 Lithology of Lynx-1X. Detailed lithology of the well from 2520 m to 5300 m is described below. • 2520 – 2558 m: Claystone and Additives. Claystone: Yellowish grey to pale yellowish brown, non-calcareous, firm, swelling, moderately hard, sub-blocky to fissile, slightly waxy, slightly micaceous. Additives, drilling mud coating the cuttings and casing cement. • 2558 – 2580 m Claystone: Yellowish grey locally light brownish grey, non-calcareous, firm, non-swelling, moderately hard, sub-blocky to sub-fissile, slightly waxy, slightly micaceous. • 2580 – 2600 m Claystone: light brownish grey, medium dark grey, white to yellowish grey, non-calcareous, firm, swelling, moderately hard, waxy, sub-fissile to fissile, slightly micaceous. • 2600 – 2743 m Claystone: Medium dark grey to medium light grey, slightly calcareous 28 University of Ghana http://ugspace.ug.edu.gh to non-calcareous, firm, swelling, moderately hard, sub-fissile to fissile, waxy, slightly micaceous, trace pyrite. • 2743 - 2813 m: Claystone: Dark grey to medium dark grey, brownish, non-calcareous, firm, non-swelling, moderately hard, sub-blocky to sub-fissile, slightly waxy, slightly micaceous. • 2813 - 3100 m Claystone: Medium grey and dark medium grey to brownish grey and brownish black, non-calcareous to slightly calcareous, firm, non-swelling, moderately hard, sub-blocky to fissile, slightly waxy, micaceous to slightly micaceous, trace indeterminate biogenic debris. • 3200 – 3262 m Claystone: Brownish grey to brownish black, slightly calcareous to calcareous, firm, non-swelling, moderately hard to hard, sub-blocky to blocky, silty, trace biogenic debris. Siltstone, trace, medium light grey to light brownish grey, noncalcareous, firm, non-swelling, moderately hard, blocky, speckled with black minerals. Additives, drilling mud coating cuttings. • 3262 – 3300 m Claystone: Brownish grey, calcareous, firm, non-swelling, moderately hard, sub-blocky, silty. Marl, very light grey, speckled with dark brown to black minerals, firm, moderately hard, blocky, locally finely laminated. • 3300 - 3340.50 m Claystone: Medium dark grey to brownish grey, slightly calcareous to calcareous, firm, swelling, moderately hard, sub-blocky to sub-fissile, slightly micaceous, slightly organic. • 3340.50 – 3705 m Claystone: Medium dark grey to brownish grey, non-calcareous to slightly calcareous, firm, slightly swelling to swelling, moderately hard, sub-blocky to sub- fissile, slightly micaceous. Silty claystone, medium grey to brownish grey and brownish black, slightly calcareous to calcareous, firm, slightly swelling, moderately hard, sub-blocky to sub- fissile, slightly micaceous, slightly bituminous. 29 University of Ghana http://ugspace.ug.edu.gh • 3705 – 3760 m Silty Claystone: Medium grey to brownish grey and brownish black, slightly calcareous to calcareous, firm, slightly swelling, moderately hard, sub-blocky to subfissile, slightly micaceous, slightly bituminous. • 3760 – 3803 m Silty claystone grading to Siltstone: Light brownish grey to brownish grey, locally light olive grey, slightly calcareous, firm, moderately hard to hard, non-swelling, sub-blocky, indeterminate biogenic debris. • 3803 – 3960 m Silty claystone grading to Siltstone: Light brownish grey to brownish grey, slightly calcareous to calcareous, firm, non-swelling, moderately hard to hard, subblocky, slightly micaceous, slightly bituminous, trace pyrite. • 3960 – 3980 m Siltstone: Mottled yellowish grey, light olive grey, white to very light grey, slightly calcareous, firm, non-swelling, hard, blocky. • 3980 -3991 m Silty claystone: Brownish grey to brownish black, calcareous, firm, nonswelling, sub-blocky to sub-fissile, slightly bituminous, slightly micaceous. Limestone, very pale orange to white, argillaceous, moderately hard, mudstone to wackestone, blocky. Siltstone, as above, slightly greenish grey. • 3991 – 4000 m Silty Claystone: Brownish grey, slightly calcareous, firm, hard, nonswelling, slightly blocky, finely laminated with sandy stingers. Sandstone, light brownish grey, consolidated, slightly calcareous, hard, very fine sand grade, sugary, clast-supported, sub-angular. • 4000 - 4100.80 m Silty claystone: Medium grey to brownish grey, slightly calcareous to calcareous, firm, non-swelling to slightly swelling, moderately hard, sub-blocky, slightly micaceous, gritty. Argillaceous silty limestone, yellowish grey to very light grey, firm, moderately hard, blocky. • 4100.80 – 4120 m Siltstone: Brownish grey, calcareous, firm, non-swelling, hard, subblocky to sub-fissile, highly micaceous. 30 University of Ghana http://ugspace.ug.edu.gh • 4120 – 4260 m Siltstone grading to Silty claystone: Brownish grey to medium dark grey, slightly calcareous to calcareous, firm, non-swelling to slightly swelling, moderately hard, sub-blocky, slightly micaceous to micaceous, slightly bituminous. Argillaceous silty limestone, yellowish grey to very pale orange, soft to moderately hard, blocky, speckled with black minerals. • 4260 - 4333.20 m Claystone: Brownish grey to brownish black, non-calcareous, firm, no swelling, moderately hard to hard, sub-blocky, slightly micaceous, bituminous. Limestone, pale yellowish brown to very pale orange, moderately hard to hard, blocky, mudstone, oily shows. Silty Sandstone, light olive grey, non-calcareous, firm, non-swelling, hard, poorly sorted, silt to fine sand grade, sub-angular, translucent, biotite and dark glassy minerals. Silty claystone, brownish grey, calcareous, firm, non-swelling, moderately hard, sub-blocky to sub- fissile, micaceous, slightly bituminous. • 4333.20 – 4340 m Sandstone: Pale yellowish brown to light grey, consolidated, hard to very hard, calcareous, moderately sorted, very fine to medium sand grade, translucent, subangular, sub-spherical, micaceous. • 4340 – 4495 m Siltstone: Yellowish grey to very pale orange, non-calcareous, soft, swelling, blocky, massive, trace black minerals. Silty claystone, brownish grey to brownish black, non-calcareous, firm, moderately hard, blocky, micaceous. Sandy Siltstone grading to Sandstone, very pale orange to pale yellowish brown, non-calcareous to calcareous, firm, soft, swelling, blocky, massive, very fine to fine sand grade grains, trace black minerals. Additives, drilling mud coating cuttings. • 4495 – 4500 m Siltstone: Brownish grey to brownish black, slightly calcareous, firm, moderately hard, non-swelling, finely laminated, sub-blocky to sub-fissile, micaceous. • 4500 – 4578 m Siltstone: As above. Trace pyrite. Also, yellowish grey to light grey, 31 University of Ghana http://ugspace.ug.edu.gh calcareous, firm, slightly swelling, moderately hard, blocky, micaceous, trace pyrite. Silty claystone, brownish black to medium dark grey, non-calcareous, firm, swelling, hard, blocky, slightly micaceous, organic. Sandy siltstone, light grey to pale yellowish brown, non- calcareous, firm, swelling, moderately hard, blocky, gritty, contains very fine sand grade quartz grains. Limestone: white to very light grey, finely laminated with siltstone, mudstone texture, moderately hard, argillaceous. • 4578 – 4600 m Silty claystone: Brownish grey, slightly calcareous, firm, swelling, moderately hard, sub-blocky to sub-fissile, slightly micaceous. • 4600 – 4620 m Silty claystone: As above. Marl, yellowish grey to light grey, firm, swelling, moderately hard, blocky, contains trace black minerals. Trace sandy siltstone. • 4620 – 4700 m Claystone: Medium light grey to light brownish grey, non-calcareous, firm, swelling, moderately hard, blocky, sticky, slightly waxy, micaceous. Siltstone, pale yellowish brown, calcareous, firm, swelling, moderately hard, blocky, micaceous. • 4700 – 4780 m Claystone grading to Silty claystone: Light grey to pale yellowish brown, locally light brownish grey to brownish grey, slightly calcareous, firm, swelling, moderately hard, sub-blocky to sub-fissile. • 4780 – 4860 m Claystone: Medium grey to brownish grey, non-calcareous, firm, swelling, moderately hard, sub-blocky to sub-fissile, micaceous, slightly silty, occasional strong hydrocarbon odour. • 4860 – 4885 m Siltstone grading to silty sandstone: Yellowish grey to very pale brown, calcareous, firm, moderately hard, blocky, mottled. Siltstone, light brownish grey, slightly calcareous, firm, swelling, hard, blocky to sub-blocky, micaceous. Sandstone, yellowish grey, calcareous, consolidated, matrix supported, hard, blocky, well sorted, fine to medium, sub- angular, translucent grains, trace mica. Claystone, as above. • 4885 – 4925 m Silty Claystone: Light brownish grey to light grey, non-calcareous, firm, 32 University of Ghana http://ugspace.ug.edu.gh swelling, moderately hard, sub-blocky, slightly micaceous. Trace marl, white to very light grey, firm, swelling, soft, blocky. Trace basement, dark greenish grey, mottled with quartz and calcite veins, hard to very hard, massive. • 4925 -5300 m: Silty claystone: Light brownish grey to light grey and medium grey, non-calcareous, firm, swelling, moderately hard, sub-blocky to sub-fissile, slightly micaceous. Siltstone, yellowish grey to light grey, locally light brownish grey, calcareous, firm, swelling, soft, sub-blocky, slightly sandy. Contains? foraminifera bioclasts and locally contains? dolomite crystals. Trace anhydrite, white, soft, opaque, amorphous, massive, blocky. 3.1.2 Dzata-1 well. Dzata-1 well is the first exploratory oil well drilled in the DWCTP block in the year 2009 offshore Tano Basin and was operated by Vanco Ghana Ltd. It is represented by 100 well cutting samples. Dzata-1 well is located geographically on these coordinates; Latitude 4° 04′ 52.4307″ N, and Longitude 1° 56′ 42.4541″ W (Fig. 1.4), which attained a total depth of 4433 m. 3.1.2.1 Lithology of Dzata-1. Detailed lithology of the well from 2450 m to 4430. m is described below (Fig. 3.1); • 2450 – 2690 m: Claystone and Casing Cement/Additive. Claystone: Olive grey to olive black, non-calcareous, locally glauconitic, firm, amorphous. Casing Cement/Additive, very light grey, calcareous, firm, crumbly. • 2690 - 2718.5 m: Claystone and Casing Cement/Additive. Claystone: Olive grey, non-calcareous, firm, sub-blocky. Casing Cement/Additive, very light grey, calcareous, firm and crumbly. 33 University of Ghana http://ugspace.ug.edu.gh • 2718.5 – 2901 m: Claystone and Marl. Claystone: Brownish grey to olive grey, slightly to highly calcareous, firm, sub-blocky. Marl: brownish grey, firm, sub-blocky. • 2901 – 2982 m: Claystone, Marl, ?Dolomitic Limestone and Calcite. Claystone: Olive grey, slightly to highly calcareous, firm, amorphous to sub-blocky, locally glauconitic. Marl: brownish grey, firm, sub-blocky. Minor ?Dolomitic Limestone: light brownish grey, hard, blocky. Minor Calcite, whitish, blocky, loose grains. • 2982 - 3502 m: Claystone, Marl, Silty Claystone, Sandstone and Casing Cement/Additive Claystone: Light olive grey to olive grey to brownish grey, non-calcareous to very calcareous, fairly-firm, sub-rounded to sub-blocky. Marl: light olive grey, silty, sub-blocky, fairly-soft. Silty Claystone: olive grey to olive black, moderately to highly calcareous, fairly-firm, amorphous to sub-blocky. Minor Sandstone: very fine grade, rounded, very well sorted, unconsolidated. Casing Cement/Additive, very light grey, calcareous, firm, crumbly. • 3502 – 4430 m: Claystone, Marl, Limestone and Sandstone. Claystone: Olive grey, non-calcareous to very calcareous, fairly-firm, sub-blocky. Marl: light olive grey, silty, fairly-soft, sub-blocky. Limestone: yellowish grey, silty, soft, amorphous. Minor Sandstone, light olive grey, medium grade, grain-supported, calcareous, firm. 34 University of Ghana http://ugspace.ug.edu.gh 3.1.3 The Dzata-2A well. The Dzata-2A well is an appraisal oil well drilled in the Deep-Water Cape Three Points (DWCTP) block offshore Tano Basin formally operated by Vanco Ghana Ltd in 2011. It is represented by 101 well cutting samples. Dzata-2A well is located geographically on these coordinates; Latitude 4° 05′ 48.78″ N, and Longitude 1° 56′ 56.88″ W (Fig. 1.4), which attained a total depth of 4450 m. 3.1.3.1 Lithology of Dzata-2A. Detailed lithology of the well from 2520 m to 4470 m is described below (Fig. 3.1); • 2420 – 2649 m: Claystone and Casing Cement/Additive. Claystone: Olive grey to olive black, non-calcareous, locally glauconitic and locally grading to Silty Clay, with very fine to no visible quartz grains. Blocky, firm and amorphous. Casing Cement/Additive, very light grey, calcareous, firm, crumbly. • 2649 – 2676 m: Claystone and Silty Clay. Claystone: Olive black to black, medium firm to firm, blocky and amorphous, noncalcareous. Locally grading to Silty Clay. • 2676 – 2915 m: Claystone and Siltstone. Claystone: Brownish black to grayish black, highly calcareous, firm, blocky. Siltstone: brownish black to black, blocky. Very fine to non-visible quartz grains, poorly sorted. Traces of glauconite and light brown calcite crystals. Casing Cement/Additive, very light grey, calcareous, firm, crumbly. • 2901 – 2982 m: Claystone and Siltstone. Claystone: Brownish black to grayish black, highly calcareous, firm, blocky. Siltstone: brownish black to black, blocky. Very fine to non-visible quartz grains, poorly sorted. Traces of glauconite and light brown calcite crystals. 35 University of Ghana http://ugspace.ug.edu.gh • 2963 – 3875 m: Siltstone, Sandstone and localized Dolomite. Siltstone: Medium dark grey to dark grey, blocky, soft to firm, moderately argillaceous, grading to Sandstone in parts, very light grey, pepper texture due to phosphate as a secondary mineral, very fine to non-visible quartz grains, poorly sorted. Localized Dolomite, dark grey to brownish black, micro-crystalline, non-visible porosity, very hard. Trace glauconite. • 3875 – 4470 m: Siltstone and Sandstone. Siltstone: Medium dark grey to dark grey, blocky, soft to firm, moderately argillaceous, grading to Sandstone in parts, very fine to non-visible quartz grains, poorly to moderately sorted. Sandstone: transparent to localised off white quartz grains, very fine lower to fine lower. Localised Dolomite, dark grey to brownish black, micro-crystalline, non-visible porosity, very hard. Kaolin spots, off-white. 36 University of Ghana http://ugspace.ug.edu.gh Lynx-1x Dzata-1 Dzata-2A Depth Lithology Lithogical Depth Lithogical Depth Lithogical (m) Lithology Lithology unit (m) unit (m) unit 2520 2450 Claystone 2420 Claystone 2670 Claystone and siltystone 2980 2900 Claystone Claystone and marl 3500 3705 Silty claystone 3760 Siltstone Siltstone and sandstone 3980 Silty claystone 4100 Siltstone 4120 4260 Silty claystone Claystone, marl and 4333 ClaystoneSandstone limestone4340 Siltstone 4578 4620 Silty claystone Claystone 4860 4885 Silty sandstone 4430 4470 Silty claystone Not drawn to scale 5300 Figure 3.1: Lithology of Lynx-1X, Dzata-1 and Dzata-2A wells. 3.2 METHODS 3.2.1 Sample preparation and palynological analysis. Total of 341 cutting samples from 3 wells (Lynx-1X, Dzata-1, Dzata-2A) in the Tano Basin were obtained from the Core laboratory of GNPC. The samples were processed in the Faculty of Geoscience GML laboratory, Utrecht University, Utrecht, the Netherlands, producing a total of 1,023 palynological slides (2 slides from unoxidized residues and 1 slide from oxidized residues samples for each analysed sample interval) for this study. 37 University of Ghana http://ugspace.ug.edu.gh 3.2.2 Sample Processing Techniques. The standard palynological procedures of processing samples followed those outlined by Phipps and Playford (1984) which are described in detail in the following paragraphs. 3.2.2.1 Sample Crushing and Drying. Sample Crushing About 8 gm was processed from each sample interval. Sample code was written on the cover and container to be used for the treatments. Codes were generated for all the studied samples with labels indicating the well name, depth interval, country, weight and sieve used. Samples were crushed by selecting the biggest sample cutting and crushed with a clean crushing bowl and pestle to about 5 mm fragments and emptied into the nalgene container on the balance. The procedure was repeated until desired weight was obtained. The sample was covered and put aside. Crushing bowl and pestle were cleaned after each sample to prevent contamination from previous samples. Samples were then transferred into the oven for drying at 60 degrees Celsius and left overnight and then emptied into the labelled container. 3.2.2.2 Pre-Hydrofluoric Acid (HF) Treatment Samples were transferred into fume chamber (FC) for first stage of HCl treatment. One tablet of Lycopodium with known amount of Lycopodium clavatum marker spores was added to each sample to enable quantification of the palynomorphs and their accumulation rates (ARs) to the sediment. Few drops of agepon (kind of soap solution) were added from the water bottle onto the Lycopodium in the sample to aid coating removal. 10% HCl solution was added to each sample slowly and swirled. The process was repeated till all the calcareous materials were out and then solution added to about half full of the container. This repeated process was very important because any carbonate left would form insoluble 38 University of Ghana http://ugspace.ug.edu.gh precipitates of secondary fluorides (Ca2F, Mg2F) upon treatment with HF. This took about 1-4 hrs depending on the type of samples analyzed and distilled water added to each sample to about 3/4th full of container. Samples were tightly closed and left in the fume chamber overnight on the sample shelf. Procedures were repeated for all the samples. 3.2.2.3 (38-40%) Hydrofluoric acid (HF) treatment Step A. Before HF treatment the acid solution on samples were decanted as far as possible and filled with distilled water. Samples were transferred to the HF laboratory for centrifuging and HF treatment. Samples were centrifuged at 2200 rpm, 5 mins, acc 9, break 6. Samples were carefully removed from the bucket one after the other. Each solution was carefully decanted and the process repeated for all the samples. HF treatment was started by adding a little concentrated HF (38-40%) or five drops in each sample and swirled by holding the base stacked to the working area and put placed back to resting position. The procedure was repeated by adding more HF until half (½) full of sample container. All samples were closed and transferred to the shaking machine. Step B: Shaking Each sample was placed on the shaking machine with the timer set to 120 mins. 250 mot 1/min programme. Samples were then shook for 2 hours. After shaking, the samples were uncovered simultaneously and washed at the edges with water under a pressure from the water bottle and filled to about 4/5th full of the container and left overnight with tightly closed covers. Procedure was repeated for all the samples. HF treatment removed the silica and silicates content of the rock matrix with resultant release of organic material. 39 University of Ghana http://ugspace.ug.edu.gh 3.2.2.4 Sieving, Ultrasonification and Centrifuging. Ultra-Sonic machine (USM) was filled with tap water to the operation level after it was cleaned, and polyester sieves were placed in for 5mins after switching on the USM. Sample was rinsed slowly from its container into the sieve using water and were transferred after sieving into the labelled test tubes and centrifuged for about 25 minutes. Sieving combined with ‘sonification’ produced exquisitely clean size-sorted residues. All centrifuged samples were decanted and the residues made loose by using the vortex and 6 drops of glycerin water was added. The mixed residue was carefully transferred into the small residue vials which were labeled based on sample codes. The procedure was repeated for all the samples. All samples were centrifuged and decanted and corked for making slides. 3.2.2.5 Oxidation. Oxidation was carried on most of the samples for detailed palynological study. It was done using Schultze solution (KCIO3 in HNO3) overnight and palynomorphs showed marked improvements. The concentration and appearance of palynomorphs were further enhanced when SOBO solution (SOBO S) was added to the residue and ultrasonified for few seconds. Organic residues were concentrated in cryogenic vials and preserved by adding two drops 10% hydrochloric acid to prevent algae and fungi growth. 3.2.2.6 Mounting. Method A: Mounting before oxidation Small amount of glycerin gel was placed on a slide and a drop of thoroughly mixed residue was place on slide to be mounted. The slide with the residue was heated immediately for few seconds to dissolve the glycerin gel using the lighted burner. Two slides were mounted for each sample code. The pointed needle was used to completely spread the residue uniformly on the 40 University of Ghana http://ugspace.ug.edu.gh slide. A cover slip was slightly heated and gently placed on the slide with the help of the hooked needle. The prepared slide was placed back in the heat for less than 7 seconds and removed. The prepared label was then fixed on the mounted slide according to its sample code. The procedures were repeated for all the samples. The mounted slides were dried (between 14-18 hrs) and later cleaned and polished using a razor and cover glass polish and placed in the various slide box. Two slides were prepared for each sample before oxidation process and one slide each after oxidation. Method B: Mounting after oxidation Few drops of a solution of Polyvinyl alcohol (PVA; 10 gms in 100 mls of water) was added to diluted residues for mounting permanent slides and mixed thoroughly for even distribution of the residue on cover slip and allowed to dry on a hot plate. Permanent slides using Glue 4 Glass (G4G) was applied to residues. Two drops of G4G were placed on glass slide and placed on the cover slip with dried residue on hot plate. Prepared slide was cured in visible light using a desk lamp containing fluorescent lamp and Slide washed with soap and water after bonding to remove excess mounting medium. The procedure was applied to all the residues and permanent slides were mounted. 3.2.3 Microscopic Study and Photomicrography. The slides were studied using Olympus CK41 light microscope and Leica DM2500 LED microscope fitted with Leica MC170 HD digital camera connected to a monitor for photomicrography. The slides were placed on the mechanical stage of the microscope with the label to the left of the observer and the co-ordinates quoted refers to the mechanical stage of this microscope with 41 University of Ghana http://ugspace.ug.edu.gh the horizontal scale given first followed by the vertical scale (e.g. 135.9/18.7). England Finder Slide was later used together with sample slide for photomicrography. Each slide was thoroughly scanned for complete coverage. Well preserved species on each slide was photographed. 3.2.4 Repository All slides used in the project are deposited in the core laboratory of Ghana National Petroleum Corporation (GNPC) and with their permission duplicate slides prepared are deposited in the Research Laboratory of the Department of Earth Science, University of Ghana. Procedure adapted for labelling slides are (1) Well name (2) Country and year drilled (3) Company (4) Sample interval and size of sieve used (5) weight of sample (6) slide number prepared for a particular sample. 3.2.5 Palynofacies and Palaeoenvironmental Analysis. Examination and study of palynomorphs were done using oxidized residue slides while palynofacies analysis was performed on the unoxidized residue slides. A total of 500 particulate organic matter (POM) were counted for each sample to determine the relative abundance in percentage of POM at each sample depth interval of all the wells. Based on the quantitative analysis from microscopic observations of the different POM which were assessed according to the pattern and organized relationship between them and established the differences in the studied succession using the palynofacies approach, palynofacies associations were revealed. Relationship and range charts were produced using Tilia version 2.6.1 (2019) and StrataBugs version 2.1.1. 42 University of Ghana http://ugspace.ug.edu.gh AOM-Phytoclast-Palynomorphs (APP) ternary plot (Tyson, 1993 & 1995) were used to infer and determine the depositional environments and the relative proximity to terrestrial organic matter sources (Tyson 1995). 3.2.6 Geochemical Analysis In Geochemical analysis, the purpose of geochemical logging and cross plots is to measure the following parameters relating to source rock evaluation in sedimentary rocks: quantity of organic matter, quality of the organic matter and the thermal maturation of the organic matter. The knowledge of these three parameters will permit accurate evaluation of the source rock geochemistry and hydrocarbon potential in the oil block. 43 University of Ghana http://ugspace.ug.edu.gh CHAPTER FOUR PALYNOSTRATIGRAPHY 4.1 INTRODUCTION The processed samples from the wells (Lynx-1X, Dzata-1 and Dzata-2A) yielded well preserved and relatively diverse assemblages of dinoflagellate cysts and sporomorphs. Dinoflagellate cysts have been used for biostratigraphical purposes, with sporomorphs providing additional supporting evidence for the upper Late Cretaceous (Campanian- Maastrichtian) to Early Tertiary (Paleocene-Eocene) sediments and sporomorphs for the upper Early Cretaceous (Albian) to lower Late Cretaceous (Cenomanian). This is because many of the independently calibrated events for dinocyst were not recovered in the analyzed samples of study within the lower Cretaceous. Dinoflagellate cysts and sporomorphs recognized in this study have been reported from the Cretaceous to Tertiary sediments of Africa (e.g. Cote D'Ivoire, Sudan, Nigeria, Egypt, Angola, Senegal) and different territories such as South America (e.g. Brazil, Venezuela, Peru). Four palynozones (palynozone I, II, III and IV) have been proposed for the sediments from the processed samples of the research. The results of the palynological analysis of the studied wells are displayed on distribution charts (Appendices 1-3). Palynozonation (PZ) and age assignment of the samples studied were based on first appearance datum (FAD) and the last appearance datum (LAD) of index species and other associated species within the three wells studied (Lynx-1X, Dzata-1 and Dzata-2A) located in the Deepwater Cape Three Points oil Block, offshore Tano Basin. Correlation of lithology, palynozones and depositional environments of the three wells were also displayed (Fig. 4.11). 44 University of Ghana http://ugspace.ug.edu.gh 4.2 PALYNOZONATION (PZ) AND AGE ASSIGNMENT 4.2.1 Palynozone I (PZ-I): Afropollis jardinus-Sofrepites legouxae-Elaterocolpites castelaini Assemblage Zone This palynozone is recognized at depth intervals between (3710 – 3720 m) - (5155 – 5160 m) for Lynx-1X, (3050 – 4390 m) for Dzata-1 and from 2943 m – 4426 m for Dzata-2A (Figs. 4.1- 4.3). Definition of zone: FAD of Afropollis jardinus, Elaterocolpites castelaini and LAD of Sofrepites legouxae and Galaeocornea causea. Associated taxa group: Ephedripites brasiliensis, E. barghoonii, Classopollis brasiliensis, Tricolpites, Triplanosporites, Cicatricosisporites, Cyathidites australis, Cyclonephelium brevispinatum, Spiniferites, Subtilisphaera pellucida, Florentina laciniata and F. cooksoniae. Remarks: Recovered palynological assemblages were dominated by terrestrial palynomorphs with little to no recovery of marine palynomorphs in some intervals of this zone. The derived taxa in PZ-I are similar in all the studied wells. The sporomorphs are dominated by gymnosperm pollen grains with few pteridophyte spores and angiosperm pollen grains. This palynozone is characterized by the first and last occurrences of several other index sporomorph species such as Elaterosporites klaszii, Elateroplicites africaensis and Afropollis kahramanensis which were recovered in all the three wells. Palynozone I is subdivided into four subzones 1-4 which are detailed below; Subzone 1: Afropollis jardinus-Elaterosporites klaszii Interval Zone Definition of subzone: FAD of Afropollis jardinus and Elaterosporites klaszii. 45 University of Ghana http://ugspace.ug.edu.gh Discussions and Age assessments of subzone: Afropollis jardinus reported in subzone 1 recorded its FAD at level 5135 m – 5140 m, 4390 m and 4363 m for Lynx-1X, Dzata-1 and Dzata-2A wells respectively. A. jardinus is widely accepted as entering the stratigraphical record in the Early Albian in the Elaterates Phytogeographical Province (Doyle et al. 1982; Hochuli and Kelts 1980; Jardiné and Magloire 1965; Muller 1966; Regali et al., 1974). A. jardinus was documented in Egypt in the Aptian (Ibrahim 1996), Albian-Cenomanian (El-Beialy et al., 2010; Ibrahim, 1996), Albian-Early Cenomanian (Schrank, 2001), Early Aptian (Sultan, 1986), Aptian-Early Cenomanian (Mahmoud et al., 2000), Aptian-Albian in Egypt (Ibrahim et al., 2001). In Sudan, A. jardinus was recorded from the Aptian-Albian (Ibrahim, 2002), Late Albian-Early Cenomanian (Schrank, 2001), Albian-Cenomanian (Cole et al., 2017), Late Aptian-Late Cenomanian (Schrank, 1990) and in Libya from the Albian-Cenomanian (Batten and Uwins, 1985) and Early Cenomanian (Keegan and Stead 2007). A. jardinus was documented in Nigeria from Late Albian-Early Cenomanian (Lawal and Moullade, 1986), Early-Middle Cenomanian (Abubakar et al., 2011) and Late Aptian- Cenomanian (Salard-Cheboldaeff, 1991). A. jardinus was also reported in Brazil from Early Albian-Early Cenomanian sediments (Herngreen, 1973, 1975), Barremian-Aptian (Muller et al., 1987), Aptian-Early Cenomanian (Regali et al., 1985) and Aptian-Albian (de Lima and Boltenhagen, 1981). A. jardinus was documented in the Late Albian in Senegal (Jardinè and Magloire, 1965), Albian (Brenner, 1968) and Aptian-Albian in Peru (Ibrahim, 2002) and in Gabon (Wood et al., 1997). Elaterosporites klaszii observed in this subzone first appeared at level at 4580 m, 3950 m and 3850 m for Lynx-1X, Dzata-1 and Dzata-2A wells respectively. The first occurrence of E. klaszii is accepted to document the base of the Middle Albian in the Elaterates Phytogeographical Province (Muller, 1966; Hochuli, 1981; Jardiné, 1967; Jardiné and 46 University of Ghana http://ugspace.ug.edu.gh Magloire, 1965; Schrank and Ibrahim, 1995; Deaf et al., 2014). Elaterosporites klaszii was observed in Senegal in the Cenomanian (Kotova,1978), Early Cenomanian (Babinot et al., 1988) and from Late Albian-Early Cenomanian (Salard-Cheboldaeff,1991). In Peru, E. klaszii was documented from the Albian-Cenomanian (Brenner, 1968), Late Albian (Brenner, 1976) and in the Albian (Volkheimer,1980). In Brazil, E. klaszii was reported from the Late Albian- Cenomanian (Herngreen, 1973; Dino et al., 1999), Early Albian-Late Cenomanian (Herngreen,1974; de Lima, 1978; Kherngrin and Chlonova 1983), Middle Albian-Cenomanian Brazil (Regali, et al., 1974), Albian (Regali,1989), Early Cenomanian (Carvalho and Pedrao, 1998), Aptian-Albian (Beurlen and Regali, 1987), Albian (de Lima and Boltenhagen, 1981) and Late Albian-Early Cenomanian (Herngreen and Jimenez, 1990). E. klaszii was also documented in Egypt from the Albian-Early Cenomanian (Saad, 1974; Sultan,1987; Ibrahim, 1996; Mahmoud et al., 1999), Cenomanian (Urban, et al., 1976), Albian (Sultan,1978; Abdel-Kireem et al., 1996), Aptian-Early Albian (Saad,1978), Middle Albian (Penny,1991), Albian-Early Cenomanian (Aboul Ela and Mahrous, 1992; El-Beialy, 1994), Early Cenomanian (El-Beialy, 1993), Late Aptian-Early Albian (El-Beialy et al., 1990), Late Albian-Early Cenomanian (Mahmoud et al. 2000), Albian-Cenomanian (Schrank and Ibrahim, 1995) and Late Albian-Late Albian/Early Cenomanian (El Beialy et al., 2008). In Sudan, E. klaszii was documented from the Aptian-Cenomanian (Kaska,1989), Late Albian- Early Cenomanian (Schrank,1990, 1994) and Aptian-Cenomanian (Christopher et al., 1996). E. klaszii was reported from the Late Albian-Turonian in Venezuela (Helenes and Somoza, 1999) and Albian-Cenomanian in Tanzania (Srivastava and Msaky, 1999). E. klaszii was also documented from Late Albian-Early Cenomanian (Doukaga, 1980) in Gabon, Middle Albian- Lower Cenomanian age in Ghana (Atta-Peters, 2013; Atta-Peters and Achaegakwo, 2016), Cenomanian in the Atlantic Ocean (East) from the Cote D'Ivoire-Ghana transform margin, 47 University of Ghana http://ugspace.ug.edu.gh Sites 959, 960, 961 and 962 (Masure, et al., 1998) and in Ivory Coast from the Late Albian- Cenomanian (Jardiné,1967) and Late Albian-Early Cenomanian (Salard-Cheboldaeff, 1991). Elaterosporites klaszii was recorded in Libya in the Albian (Thusu et al., 1985) and from the Albian-Cenomanian (Batten and Uwins, 1985). Elaterosporites protensus was recognized together with E. klaszii and E. verrucatus in this subzone. In Lynx-1X, Dzata-1 and Dzta-2A wells, Elaterosporites protensus made its first appearance at depth 4580 m, 3950 m and 3850 m respectively. Jardinè (1967) and Jardinè and Magloire (1965) reported Elaterosporites protensus first in sequence followed by other Elaterosporites forms in Senegal, Ivory Coast and Gabon from Middle-Late Albian/Early Cenomanian sediments. E. protensus was later observed in Brazil from the Early-Middle Albian (Mữller, 1966), Late Albian (Herngreen, 1973), Early-Late Albian (Herngreen, 1974, 1975), Middle-late Albian (Regali et al., 1974), Albian-Cenomanian (Daemon, 1975; de Lima, 1978; de Lima and Boltenhagen, 1980; Herngreen & Chlonova, 1981; Kherngrin and Chlonova, 1983; Batten, 1996), Late Albian-Cenomanian (Dino et al., 1999). I n Senegal, E. protensus was recovered in the Early Cenomanian (Babinot et al., 1988) and Albian-Early Cenomanian in Senegal and Ivory Coast (Salard-Cheboldaeff, 1991). E. protensus was documented in Sudan from Aptian-Cenomanian (Kaska, 1989; Christopher et al., 1996) and Albian-Cenomanian in Tanzanian (Srivastava and Msaky, 1999). In Egypt, E. protensus was reported in the Early Cenomanian (Mahmoud et al., 1999) and from the Late Albian-Early Cenomanian (Deaf et al., 2014). In Morocco, E. protensus was recovered from the Albian (Bettar and Meon, 2006) and from Late Albian in Nigeria (Abubakar et al., 2006 and 2011). E. protensus was later recovered in Ghana from the middle Albian-Early Cenomanian from the Tano Basin (Atta-Peters and Salami 2006; Atta-Peters 2013; Atta-Peters and Achaegakwo 2016). 48 University of Ghana http://ugspace.ug.edu.gh Elaterosporites verrucatus observed in this palynozone first appeared at depths 4580 m, 3950 m and 3770 m for Lynx-1X, Dzata-1 and Dzata-2A wells respectively. In Egypt, Schrank and Ibrahim (1995), Sultan (1987) observed Elaterosporites verrucatus from the Albian-Early Cenomanian and from the Middle Albian-Early Cenomanian (Aboul Ela and Mahrous, 1992). E. verrucatus was reported in Senegal in the Middle Cenomanian (Babinot et al., 1988), Albian-Early Cenomanian (Salard-Cheboldaeff, 1991), Late Albian-Early Cenomanian (Jardiné, 1967; Potonie, 1970), Late Albian-Early Cenomanian and in Sudan from the Aptian- Cenomanian (Christopher and Goodman,1996; Kaska, 1989). E. verrucatus was documented Brazil in the Late Albian (Herngreen, 1973), Early Albian-Late Cenomanian (Herngreen,1974; Herngreen, 1975), Middle Albian-Late Albian (Regali et al., 1974), Albian-Early Cenomanian (Lima, 1975), Albian-Cenomanian (de Lima, 1978; de Lima and Boltenhagen, 1981; Batten, 1996), Early Albian-Middle Albian (Volkheimer, 1980) and Albian (Regali et al., 1985). E. verrucatus was also observed from Late Albian-Cenomanian in Ecuador (Dino et al., 1999), Late Albian-Turonian in Venezuela (Helenes and Somoza, 1999), Albian-Cenomanian in Tanzania (Srivastava and Msaky, 1999), Albian in Gabon (Boltenhagen, 1980), Albian-Cenomanian in Ivory Coast (Jardiné, 1967), Albian in Morocco (Bettar and Meon, 2006) and from the Late Albian-Early Cenomanian in Ghana (Atta-Peters, 2013). Masure et al. (1988) recovered Elaterosporites verrucatus, E. klaszii and E. protensus and intimated they were confined to the Middle-Late Albian of Holes 961A and 961B of the Cote D'Ivoire Ghana (CIG) transform margin. Based on the FAD of A. jardinus and E klaszii, subzone 1 of palynozone I range from the Early- Middle Albian from (5155 – 5160 m) - 4580 m in Lynx-1X well, 4390 m-3950 m for Dzata-1 well and 4426 m – 3850 m for Dzata-2A well. 49 University of Ghana http://ugspace.ug.edu.gh Age of subzone 1: Early-Middle Albian Subzone 2: Elaterocolpites castelaini Interval Zone Definition of subzone: FAD of Elaterocolpites castelaini and LAD of Sofrepites legouxae Discussions and Age assessments of subzone: In this study, Elaterocolpites castelaini was first recognized in Lynx-1X, Dzata-1 and Dzata- 2A wells at depths 4580 m, 3930 m and 3830 m respectively. E. castelaini is an index species in this interval used to document the base of the Late Albian and top of the Middle Cenomanian in the Elaterates Province in Brazil (Herngreen 1973; Herngreen and Jimenez, 1990) and in Senegal (Jardiné and Magloire 1965; Jardiné 1967). Batten and Uwins (1985) observed Elaterocolpites castelaini from the Early Albian-Late Cenomanian in Libya and from Albian- Cenomanian in Tanzania (Srivastava and Msaky, 1999). In Brazil, E. castelaini was reported from the Albian-Cenomanian (Herngreen, 1975, 1981; de Lima, 1978), Middle Albian-Cenomanian (Regali et al., 1974), Late Albian-Cenomanian (Dino et al., 1999), Albian-Turonian (Daemon, 1975) and in the Albian (Lima, 1975; de Lima and Boltenhagen, 1981). E. castelaini was documented in Senegal from the Late Albian- Cenomanian (Salard-Cheboldaeff, 1991). In Egypt E. castelaini was reported in the Cenomanian (Ibrahim, 1996), Early Cenomanian (Mahmoud et al., 1999), Middle Albian-Early Cenomanian (Aboul Ela and Mahrous,1992), Late Albian-Early Cenomanian (El-Beialy, 1994; Schrank, 2001; Deaf et al., 2014). E. castelaini in Sudan was documented from the Aptian- Cenomanian (Kaska, 1989) and Late Albian-Early Cenomanian (Schrank, 1994; Schrank, 2001). Schrank (1990) recovered E. castelaini together with Elaterosporites klaszii from Late Albian- Early Cenomanian strata from northern Sudan. Atta-Peters and Salami (2006) also reported 50 University of Ghana http://ugspace.ug.edu.gh Elaterocolpites castelaini, Elaterosporites klaszii and E. protensus and suggested a Middle Albian-Cenomanian age in Ghana. Sofrepites legouxae was first recognized in Lynx-1X, Dzata-1 and Dzata-2A wells at depths 4540 m, 3810 m and 3850 m respectively and made its last appearance at 4515 – 4520 m, 3650 m and 3354 m respectively. S. legouxae is an index species in this interval which is documented to range from the Late Albian-Early Cenomanian in Brazil (Herngreen 1973; Herngreen and Jimenez, 1990) and in Senegal (Jardiné and Magloire 1965; Jardiné 1967). S. legouxae was documented from the Late Albian-Turonian in Venezuela (Helenes and Somoza, 1999). In Brazil S. legouxae was reported in the Late Albian-Cenomanian (Herngreen, 1973 and 1974; Dino et al., 1999), Early Albian-Late Cenomanian (Herngreen, 1975), Albian-Cenomanian (de Lima and Boltengagen, 1981; Herngreen and Chlonova, 1981; Kherngrin and Chlonova, 1983; Batten, 1996), and Late Albian-Early Cenomanian (Herngreen, 1981). Herngreen et al., (1996) later documented S. legouxae to be confined to the Late Albian-Early Cenomanian of the Albian-Cenomanian Elaterate Province. S. legouxae was reported in Egypt from the Early Cenomanian (Ibrahim, 1996), Late Albian-Early Cenomanian (Aboul Ela and Mahrous, 1992; Deaf et al., 2014), Albian-Early Cenomanian (Sultan, 1987) and in Nigeria from the Late Albian-Middle Cenomanian (Lawal, 1982). Based on the FAD of Elaterocolpites castelaini and LAD of Sofrepites legouxae, subzone 2 ranges from the Late Albian-Early Cenomanian for Lynx-1X, Dzata-1 and Dzata-2A wells from 4580 m - (4515 – 4520 m), 3930 m – 3650 m and 3830 m-3354 m respectively. Age of subzone 2: Late Albian-Early Cenomanian Subzone 3: Elateroplicites africaensis Interval Zone 51 University of Ghana http://ugspace.ug.edu.gh Definition of subzone: LAD of Elateroplicites africaensis and Elaterocolpites castelaini. Discussions and age assessment of subzone: Elateroplicites africaensis and Elaterocolpites castelaini observed in subzone 3 had its last appearance at depths 3895 – 3900 m, 3050 m and 3294 m for Lynx-1X, Dzata-1 and Dzata-2A respectively. E. africaensis was reported in Brazil from Albian-Cenomanian (Herngreen, 1973, 1974 and 1975; Herngreen and Chlonova, 1981; Kherngrin and Chlonova, 1983), Late Albian- Cenomanian (Herngreen, 1981), Late Albian-Turonian (Regali et al., 1974 and 1985), Albian- Turonian (de Lima et al., 1981) and Early Cenomanian (Carvalho and Pedrao, 1998). E. africaensis was also documented from the Late Albian-Early Cenomanian in Sudan (Schrank, 1990 and 2001) and in Egypt from Late Albian-Early Cenomanian (Schrank, 2001) and Early- Middle Cenomanian (Schrank and Ibrahim, 1995). The E. africaensis was reported from Albian-Cenomanian in Gabon, Congo, Angola and Cameroon (Salard-Cheboldaeff, 1991). According to Herngreen et al. (1996) Elateroplicites is restricted to the Middle Albian- Cenomanian. The LAD of Elateroplicites africaensis and Elaterocolpites castelaini were used to define the top of the Middle Cenomanian which range from (4515 m – 4520 m) - (3895 – 3900 m) for Lynx-1X, 3650 m – 3050 m for Dzata-1 well and from 3312 m – 3294 m for Dzata-2A well. Age of subzone 3: Early-Middle Cenomanian Subzone 4: Galeocornea causea Interval Zone Definition of subzone: LAD of Galeocornea causea and Afropollis kahramanensis. 52 University of Ghana http://ugspace.ug.edu.gh Discussions and age assessment of subzone: Galeocornea causea and Afropollis kahramanensis occurred together with other forms of Elaterosporites documented in this subzone had its LAD at 3710 m – 3720 m, 2930 m and 2922 m for Lynx-1X, Dzata-1 and Dzata-2A respectively. G. causea was recovered from Late Albian-Cenomanian of Senegal and Gabon (Jardiné and Magloire, 1965; Jardiné, 1967) and also in Brazil from the Albian-Cenomanian (Herngreen, 1973, 1975). Brenner (1968) reported G. causea from Albian-Cenomanian in Peru and the same species was recorded in Egypt from the Late Albian-Early Cenomanian (Mahmoud, 1998; Shrank & Ibrahim, 1995; Zobaa et al., 2013) and in the Middle Albian (Deaf et al., 2014). Afropollis kahramanensis was documented in Egypt from Early Cenomanian-Middle Cenomanian (Schrank et al., 1995), Late Cenomanian (Ibrahim et al., 1996; Mahmoud et al., 2000), Late Albian/Early Cenomanian-Late Cenomanian (El Beialy, 1994), Late Albian-Early Cenomanian (El Beialy, 1994), Late Cenomanian (Ibrahim, 1996), Cenomanian (Mahmoud, 1998), Early Cenomanian (Mahmoud and Moawad, 1999), Early-Middle Cenomanian (Ibrahim, 2002), Late Cenomanian (Mahmoud and Moawad (2002), Late Albian-Late Albian/Early Cenomanian (El Beialy et al., 2008) and Late Albian-Cenomanian (Deaf et al., 2014). The elater-bearing pollen and Classopollis spp. which disappeared at the end of the Late Cenomanian occurred in subzone 3 represented in Lynx-1X, Dzata-1 and Dzata-2A wells in depth intervals from (3895 – 3900 m) - (3710 – 3720 m), 3050 m – 2930 m and 3294 m – 2922 m respectively. A Late Cenomanian age is suggested for this subzone. Age of subzone 4: Late Cenomanian 53 University of Ghana http://ugspace.ug.edu.gh Other taxa restricted to this palynozone includes Ephedripites brasiliensis, Ephedripites irregularis and Ephedripites barghoonii which were documented together with the elater- bearing pollen reported above and disappeared at the end of the elaterates occurrence. E. brasiliensis was reported in the Late Albian from Senegal and Ivory Coast (Jardinè and Magloire, 1965). E. brasiliensis was also recorded from Late Albian-Early Cenomanian in Ghana (Atta-Peters and Salami, 2006) and in Brazil, from the Late Albian-Early Cenomanian (Herngreen, 1973) and Albian-Cenomanian (de Lima, 1978). Ephedripites irregularis was recovered in Brazil from Early-Middle Albian Herngreen (1973), Albian-Cenomanian (Herngreen, 1975), Aptian-Albian (de Lima, 1978), Albian-Cenomanian (Herngreen and Chlonova, 1981) and Albian-Early Turonian (Kherngrin and Chlonova, 1983). In Egypt E. irregularis was documented in the Albian (Sultan, 1978), Early Aptian (Sultan, 1986), Late Aptian-Early Albian (El-Beialy et al. 1990), Late Albian-Early Cenomanian (Aboul Ela and Mahrous, 1992), Late Albian-Cenomanian (Schrank et al., 1995) and in the Cenomanian (Ibrahim, 1996). E. irregularis was also recorded from Early Albian-Middle Albian in South America (Herngreen, 1981) and in the Tano Basin of Ghana from the Early- Middle Albian (Atta-Peters and Salami 2006). Ephedripites barghoonii was documented from the Late Albian-Early Cenomanian of Senegal and from Albian to Cenomanian sediments from Ivory Coast (Jardinè and Magloire, 1965). E. barghoonii was recorded from the Early Albian-Cenomanian (Herngreen, 1973) and Early Albian-Late Cenomanian (Herngreen, 1974, 1975) in Brazil. E. barghoonii was recovered from the Tano Basin in Ghana and suggested to be Early Albian-Early Cenomanian in age (Atta- Peter and Salami, 2006). E. barghoonii was also documented from the Early Albian-Coniacian in Angola (Morgan, 1978), Aptian-Middle Albian in Venezuela (Sinanoglu, 1983) and Albian- Cenomanian in Tanzania (Srivastava and Msaky, 1999). 54 University of Ghana http://ugspace.ug.edu.gh Classopollis brasiliensis and Classopollis classoides observed in this palynozone was recognized throughout most of the analyzed sample intervals. They appeared last at depths 3710 – 3720 m, 2930 m and 2922 m for Lynx-1X, Dzata-1 and Dzata-2A wells respectively. Classopollis brasiliensis was reported from the Middle to Late Cenomanian (Ibrahim, 2002; El Beialy et al., 2010; Tahoun and Deaf, 2016) and in the Cenomanian (Schrank et al., 1995; Ibrahim, 1996; Mahmoud et al., 2000) in Egypt. C. brasiliensis was documented from Middle- Late Cenomanian strata in Libya (Thusu and Van der Eem, 1985), Early Albian-Late Cenomanian in Brazil (Herngreen, 1975), Cenomanian in Brazil and Israel (Herngreen, 1975; de Lima et al., 1981). In Nigeria, C. brasiliensis was recorded from Middle-Late Cenomanian (Lawal and Moullade, 1986), Late Albian-Middle Cenomanian (Lawal, 1982) and Late Albian- Early Cenomanian (Ojoh, 1990). C. brasiliensis was also reported in the Atlantic Ocean (East) from the Cote D'Ivoire-Ghana transform margin, Sites 959, 960, 961, 962 (Masure et al., 1998). Atta-Peters et al. (2015) assigned an Albian-Cenomanian for the interval 6900 ft – 8550 ft of ST-7H based on the existence and persistent elater bearing pollen (e.g. Elaterosporites spp., Elaterocolpites spp., Galeocornea spp. and Ephedripites spp.) which were consistent with this palynozone. The elater-bearing pollen in this palynozone have a restricted stratigraphic distribution from the Early Albian-Late Cenomanian. They appeared in the Early Albian and disappeared at the top of the Late Cenomanian (Herngreen and Duenas Jimenez, 1990; Herngreen et al., 1996). Based on stratigraphic significant confined to palynozone I, an Albian-Cenomanian age is deduced for the analyzed samples. 55 University of Ghana http://ugspace.ug.edu.gh 4.2.2 Palynozone II (PZ-II): Cretaceaeiporites polygonalis-C. scabratus-Dinogymnium accuminatum Assemblage Zone PZ-II was recognized in two of the wells, Lynx-1X well at sample intervals from 3320 m - (3690 – 3700 m) and Dzata-2A well at sample intervals from 2802 m – 2901 m (Figs. 4.1-4.3). This zone recorded less palynomorph recovery as compared to the rest of the palynozones and dominated by terrestrially palynomorphs, hence dinoflagellates where convenient would be used as an index species to support the age assignment. Definition of Zone: PZ-II in Lynx-1X and Dzata-2A wells was characterized by the FAD of Cretaceaeiporites polygonalis Cretaceaeiporites cf. scabratus and Dinogymnium accuminatum. Associated taxa: Araucariacites australis, Cyathidites australis, Verrucosisporites, Psilastephanocolpites, Retitricolpites, Retimonocolpites spp., Inaperturatepollenites, D. accuminatum, Cyclonephelium brevispinatum, Spiniferites ramosus, Oligosphaeridium complex and Odontochitina porifera. Remarks: PZ-II is constituted by mainly terrestrial palynomorphs which are dominated by gymnosperm pollen with few pteridophyte spores and angiosperm pollen grains and low to none dinoflagellates. The palynological assemblages in Lynx-1X and Dzata-2A wells within PZ-II are low in diversity and generally fairly preserved. Discussions and age assessment: Turonian-Santonian sporomorphs like Droseridites senonicus, Hexaporotricolpites emelianovi Cretaceaeiporites spp. and dinoflagellate cysts (Dinogymnium acuminatum, Odontochitina 56 University of Ghana http://ugspace.ug.edu.gh porifera, etc.) were missing in Dzata-1 well. Droseridites senonicus was documented as a Turonian-Early Senonian (Santonian) marker species (Apaalse and Atta-Peters, 2013; Lawal and Moullade, 1986; Schrank and Ibrahim, 1995). This therefore made possible the inference of limitations or sediments erosion suggesting an unconformity between Late Cenomanian and Early Campanian of Dzata-1 well from intervals of 2910 m – 3050 m. Cretaceaeiporites polygonalis and Cretaceaeiporites scabratus observed in PZ-II first appeared at depth 3670 – 3680 m and 3690 – 3700 m for Lynx-1X well, 2901 m and 2820 m for Dzata-2A well respectively. Their LAD were restricted to this palynozone at 3580 m and 2820 m for Lynx-1X and Dzata-2A respectively. C. polygonalis was documented in Gabon from the Albian-Early Turonian (Boltenhagen, 1975) and from the Albian-Turonian (Boltenhagen, 1980). C. polygonalis was recorded in Nigeria (Odebode et al., 1984) and in Cameroon, Congo and Angola (Salard-Cheboldaeff, 1991). C. polygonalis was documented from the Turonian-Coniacian in Angola (Morgan, 1978), Early Senonian in Nigeria (Jan du Chêne 1979) and the Late Albian-Turonian in Sudan (Schrank, 1994). C. polygonalis was observed in Brazil in the Coniacian (de Lima et al., 1989). Cretaceaeiporites scabratus was reported from the Cenomanian-Early Senonian in Brazil (Herngreen, 1974; Herngreen, 1975) and in Gabon (Boltenhagen, 1975). C. scabratus was observed from the Turonian-Coniacian in Angola (Morgan, 1978), Early Senonian in Nigeria (Jan du Chêne, 1979), Coniacian and Late Coniacian in Nigeria (Odebode et al., 1986; Odebode, 1987). C. scabratus was recorded in the Senonian in Namibia (Benson, 1990), Late Albian-Turonian in Senegal and Ivory Coast (Salard-Cheboldaeff, 1991), in Sudan (Schrank, 1994), Early Turonian in Egypt (Ibrahim, 1996) and from the Late Albian-Santonian of northern Africa (Mahmoud and Mahmoud, 2007). 57 University of Ghana http://ugspace.ug.edu.gh Odontochitina porifera in this palynozone was first recognized at depth 3320 m for Lynx-1X well, 2890 m for Dzata-1 well and 2781 m for Dzata-2A well. O. porifera was documented in the Senonian (Cookson, 1956), Late Turonian-Maastrichtian (Cookson, 1960) and Turonian- Senonian (Vozzhennikova, 1965) in Australia. O. porifera was recorded from Coniacian-Early Santonian in the Atlantic Coast Offshore (Bujak et al., 1978), Late Senonian in Guinea (Masure, 1979), Turonian-Santonian in Canada (Barss et al., 1979) and Turonian-Campanian in the North Sea (Davey et al., 1977). O. porifera was reported from Coniacian-Santonian in the Northern Hemisphere (Williams et al., 1993), in Egypt (Abdel-Kireem et al., 1996) and from Turonian-Santonian in Algeria (Foucher et al., 1994). O. porifera was also observed from the Turonian-Maastrichtian in Brazil (Arai, 1994), Coniacian-Maastrichtian in Egypt (Schrank et al., 1995) and from the late Turonian-Santonian in the Atlantic Ocean (East) (Oboh-Ikuenobe et al., 1998). O. porifera was later documented from the late Santonian-early Campanian in England (Prince et al., 1999) and from the Santonian-Late Maastrichtian in the Northern Hemisphere (Williams et al., 2004). In this study, the FAD of Dinogymnium acuminatum was observed at depth 3500 m, 2910 m and 2841 m for Lynx-1X, Dzata-1 and Dzata-2A wells respectively. D. acuminatum was recorded in the Senonian (Baltes, 1973) and from Turonian-Middle Santonian (Antonescu, 1973) in Romania. D. acuminatum was reported from the Santonian-Maastrichtian in Canada (Jenkins et al., 1974; Williams et al., 1974), the Campanian in Ghana (Davey, 1975). D. acuminatum was documented from the Turonian-Coniacian in Angola (Morgan, 1978) and in Nigeria from the Albian-Turonian (Odebode et al., 1984), Santonian-Maastrichtian (Oloto 1989; Oloto et al., 2013) and in the Maastrichtian (Williams et al., 2017). D. acuminatum was reported in the Early Senonian in Libya (El-Mehdawi, 1991) and in the Early Santonian in France (Begouen, 1993). D. acuminatum was recorded from the Early Santonian-Maastrichtian 58 University of Ghana http://ugspace.ug.edu.gh in Egypt (El-Beialy, 1994), Late Turonian-Early Maastrichtian in the Atlantic Ocean (East) (Oboh-Ikuenobe et al., 1998), Turonian-Coniacian in England (Pearce et al., 2003) and from the Coniacian-Late Maastrichtian in the Northern Hemisphere (Williams et al., 2004). The absence of elater-bearing pollen and Classopollis spp. at the beginning of this palynozone at 3680 – 3690 m for Lynx-1X well and at 2901 m for Dzata-2A well marked the Cenomanian/Turonian boundary (Herngreen et al., 1996; Herngreen, 1998) which further supports the ?Turonian-Santonian of PZ-II. Age of palynozone II: ?Turonian-Santonian 59 University of Ghana http://ugspace.ug.edu.gh Sporomorphs Dinoflagellate cysts 2520 2560 2600 2640 2680 2720 2760 2800 2840 2880 2920 2960 3000 3040 3080 3120 3160 3200 3240 3280 3320 3360 3400 3440 3480 3520 3560 3600 3640 3680 3720 3760 3800 3840 3880 3920 3960 4000 4040 4080 4120 4160 4200 4240 4280 4320 4360 4400 4440 4480 4520 4560 4600 4640 4680 4720 4760 4800 4840 4880 4920 4960 5000 5040 5080 5120 5160 5200 5240 Claystone Silty claystone Siltstone Sandstone Silty sandstone Figure 4.1: Age, palynozone, lithological column and stratigraphical significant taxa from Lynx-1X well. 60 Depth/m Albian-Cenomanian ?Turonian- Campanian-Maastrichtian Paleocene-Santonian Eocene Age PZ-I PZ-II PZ-III PZ-IV Palynozone Lithology Afropollis jardinus Afropollis kahramanensis Longapertites marginatus Proxapertites cursus Proxapertites operculatus Spinizocolpites echinatus Elaterocolpites castelaini Elaterosporites klaszii Elaterosporites protensus Elateroplicites africaensis Elaterosporites verrucatus Galaeocornea causea Cretaceaeciporites polygonalis Cretaceaeciporites scabratus Sofrepites legouxae Andalusiella polymorpha Apectodinium homomorphum Cerodinium diebelii Dinogymnium acuminatum Diphyes colligerum Hafniasphaera hyalospinosa Hafniasphaera septata Homotryblium floripes Homotryblium pallidum Homotryblium tenuispinosum Ifecysta fusiforma Ifecysta lappacea Odontochitina operculata Odontochitina porifera Trichodinium castanea University of Ghana http://ugspace.ug.edu.gh Sporomorphs Dinoflagellate cysts 2440 2480 2520 2560 2600 2640 2680 2720 2760 2800 2840 2880 2920 2960 3000 3040 3080 3120 3160 3200 3240 3280 3320 3360 3400 3440 3480 3520 3560 3600 3640 3680 3720 3760 3800 3840 3880 3920 3960 4000 4040 4080 4120 4160 4200 4240 4280 4320 4360 4400 Claystone Claystone & marl Claystone, marl, limestone, sandstone Figure 4.2: Age, palynozone, lithological column and stratigraphical significant taxa fro m Dzata-1 well. 61 Depth/m Albian-Cenomanian ? Campanian-Maastrichtian Age PZ-I PZ-III Palynozone Lithology Afropollis jardinus Afropollis kahramanensis Longapertites marginatus Proxapertites cursus Proxapertites operculatus Spinizocolpites echinatus Elaterocolpites castelaini Elateroplicites africaensis Elaterosporites klaszii Elaterosporites protensus Elaterosporites verrucatus Galaeocornea causea Sofrepites legouxae Andalusiella polymorpha Cerodinium diebelii Dinogymnium acuminatum Dinogymnium undulosum Palaeocystodinium golzowense Andalusiella polymorpha Odontochitina operculata Odontochitina porifera Trichodinium castanea University of Ghana http://ugspace.ug.edu.gh Sporomorphs DinoflaPgeerlildaitneo cidys ts 2400 2440 2480 2520 2560 2600 2640 2680 2720 2760 2800 2840 2880 2920 2960 3000 3040 3080 3120 3160 3200 3240 3280 3320 3360 3400 3440 3480 3520 3560 3600 3640 3680 3720 3760 3800 3840 3880 3920 3960 4000 4040 4080 4120 4160 4200 4240 4280 4320 4360 4400 4440 Claystone Silty claystone Silty sandstone Figure 4.3: Age, palynozone, lithological column and stratigraphical significant taxa from Dzata-2A well. 62 Depth/m Albian-Cenomanian ?Turonian- Campanian-Maastrichtian Santonian Age PZ-I PZ-II PZ-III Palynozone LithoLloitghyology Afropollis jardinus Afropollis kahramensis Cretacaeisporites polygonalis Cretacaeisporites scabratus Longapertites marginatus Proxapertites cursus Proxapertites operculatus Spinizocolpites echinatus Elaterocolpites castelaini Elateroplicites africaensis Elaterosporites klaszii Elaterosporites protensus Elaterosporites verrucatus Galaeocornea causea Sofrepites legouxae Andalusiella polymorpha Cerodinium diebelii Dinogymnium acuminatum Dinogymnium undulosum Odontochitina operculata Odontochitina porifera Trichodinium boltenhagenii Trichodinium castanea University of Ghana http://ugspace.ug.edu.gh 4.2.3 Palynozone III (PZ-III): Trichodinium castanea-Cerodinium diebelli-Dinogymnium acuminatum Assemblage Zone PZ-III occurs in all the studied wells and occurred at different depth intervals for each well. It occurred within the depth intervals (2760 – 3300 m) for Lynx-1X well, (2450 – 2910 m) for Dzata-1 and Dzata-2A (2420 – 2781 m) (Figs. 4.1-4.3). Definition of palynozone: FAD of Trichodinium castanea, Cerodinium diebeli and LAD of Dinogymnium acuminatum. Associated taxa: Cerodinium boloniense, C. obliquipes, Coronifera oceania, Andalusiella spp., Cyclonephelium vannophorum, C. distinctum, Circulodinium distinctum, Odontochitina spp., Palaeocystodinium australinium, Florentina spp., Areoligera spp., Dinogymnium spp., Glaphyrocysta divaricata, Glaphyrocysta ordinata, Adnatosphaeridium multispinosum, Cordosphaeridium inodes, Oligosphaeridium poculum, O. Complex, Achomosphaera spp., Spiniferites spp. and Xenascus ceratoides. Sporomorphs includes Longapertites proxapertitoides, L. marginatus, Proxapertites operculatus, Proxapertites psilatus, Spinizocolpites echinatus, Deltoidspora minor, Dictyophyllidites harrisii, Foveotriletes margaritae, Retimonocolpites spp., Monosulcites spp., Tricolpites confessus, Echitriporites trianguliformis and Cingulatisporites ornatus. Remarks: A significant change in the composition of the palynological association was recorded in all the three wells studied. The marine palynomorph (%) of total palynomorphs ranges from (61- 93%) in Lynx-1X well, (64-92%) in Dzata-1 well and (67-93%) in Dzata-2A well (Figs. 4.4, 4.5 and 4.6). Quantitative distribution of terrestrial palynomorphs (pollen and spores) were 63 University of Ghana http://ugspace.ug.edu.gh represented between (7-39%) of total palynomorph in Lynx-1X well, (8-36%) in Dzata-1 well and (7-33%) in Dzata-2A well. The very rich palynofloras were dominated by marine derived forms with good to very good preservation. The gonyaulacoids recovered in this zone are dominated by chorate cysts (Spiniferites, Cordosphaeridium, Areoligera, Adnatosphaeridium). The peridinoids observed in this zone of the three wells were dominated by the genera Andalusiella, Cerodinium and Palaeocystodinium. Palynozone III is subdivided into two subzones 1 and 2 which are detailed below; Subzone 1: Trichodinium castanea Interval Zone Definition of subzone: The base of this subzone is defined by FAD of Trichodinium castanea and the top by the FAD Cerodinium diebelli. Other important taxa in this subzone includes Andalusiella polymorpha, Palaeocystodinium australinium and Palaeocystodinium golzowense. Discussions and age assessment of subzone: This subzone is characterized by the FAD of Trichodinium castanea and occurred at level 3320 m for Lynx-1X well, 2910 m for Dzata-1 well and 2781 m for Dzata-2A well. T. castanea was reported in Egypt in the Campanian (Schrank, 1984, 1987 and 1988; Schrank and Perch- Neilsen 1985), Cenomanian-Maastrichtian (Schrank and Ibrahim, 1995) and the Late Campanian-Maastrichtian (El-Beialy, 1995). T. castanea was documented in the Campanian of Cote d’Ivoire (Digbehi et al., 1996; Tea-Yassia et al., 1999). In Canada, T. castanea was reported in the Campanian (Williams et al., 1974; Fensome et al., 2008), Turonian-Early Campanian (Williams, 1975) and from the Kerguelen Plateau in the Campanian (Mao and Mohr, 1992). T. castanea was recorded from the Campanian-Maastrichtian in Nigeria (Beilstein, 1994), Campanian in Brazil (Arai, 1994) and from the Early-Late Maastrichtian in 64 University of Ghana http://ugspace.ug.edu.gh the Northern and Southern Hemisphere (Williams et al., 2004). T. castanea was documented in the Early Maastrichtian (Wilson, 1974; May 1980; Costa and Davey, 1992; Slimani, 1995, 2000; Williams et al., 1993; Roncaglia and Corradini, 1997; Gradstein et al., 2005). The FAD of Cerodinium diebelli which was observed in Lynx-1X, Dzata-1 and Dzata-2A wells marked the beginning of the Late Campanian in this subzone. It occurred at level 3120 m for Lynx-1X well, 2750 m for Dzata-1 and 2620 m for Dzata-2A well. C. diebelli has been recorded in the Late Campanian-Maastrichtian of the James Ross Island area and Antarctic Peninsula (Riding, 1992), Campanian-Maastrichtian in New Jersey (Lentin et al., 1987). C. diebelli was also documented from the Campanian-Maastrichtian in France (Begouen, 1993), Early Maastrichtian in Nigeria (Beilstein, 1994), Late Campanian-Paleocene in England (Stover et al., 1996), Late Campanian-Early Maastrichtian in Netherlands (Herngreen et al., 1996). C. diebelli was reported from the Early-Middle Maastrichtian in Israel (Hoek et al., 1996), in Italy (Roncaglia and Corradini, 1997) and from the CIG transform margin (Masure et al., 1998). C. diebelli was documented in the Late Campanian of the British Isles (Costa and Davey, 1999), in the Maastrichtian of Maud Rise and Georgia Basin, Southern Ocean (Mohr and Mao, 1997) and in the Late Maastrichtian in Tunisia (Vellekoop et al., 2015). Various authors have documented the association of the taxa (Cerodinium, Phelodium, Andalusiella and Senegalinium) observed in PZ-III from the Campanian-Maastrichtian (Schrank, 1987, 1994; Salami, 1986, 1988; Schrank and Ibrahim, 1995; Atta-Peters and Salami, 2004). Andalusiella polymorpha recovered in this subzone first occurred at sample depth 3200 m for Lynx-1X well, 2750 m for Dzata-1 well and 2781 m for Dzata-2A well. Eshet et al. (1992) documented A. polymorpha in the Maastrichtian age from Israel. A. polymorpha was reported 65 University of Ghana http://ugspace.ug.edu.gh in the Campanian from Venezuela and Mauritania (Lentin and 1980), Late Campanian-Early Maastrichtian in Morocco (Rauschen et al., 1982) and in Egypt (Schrank et al., 1985). A. polymorpha was recovered from the Campanian-Maastrichtian in Namibia (Benson, 1990) and in Nigeria (Beilstein, 1994). A. polymorpha was documented from the Late Campanian- Maastrichtian in Egypt (El-Beialy, 1995) and in the Early Campanian (Williams et al., 1993). In this subzone, Palaeocystodinium australinium together with Palaeocystodinium golzowense was first recognized at depth 3180 m, 2890 m and 2781 m for Lynx-1X, Dzata-1 and Dzata- 2A respectively. P. australinium was documented from the Maastrichtian-Paleocene from Colorado Basin in Argentina (Gamerro and Archangelsky, 1981), in New Jersey from the Campanian-Maastrichtian (May, 1980) and from Late Maastrichtian-Danian in New Jersey (Landman et al., 2004). In Canada, P. australinium was recorded from Maastrichtian- Paleocene (Williams and Bujak 1977; Barss et al., 1979). P. australinium was reported from Late Maastrichtian (Rauscher et al., 1982) in Morocco from Late Maastrichtian-Early Danian (Brinkhuis and Zachariasse, 1988) in Tunisia. In Nigeria, P. australinium was observed in the Early Maastrichtian (Oloto, 1989), Maastrichtian-Eocene (Salami, 1983) and from the Campanian-Early Maastrichtian (Edet, 1992). In Egypt, P. australinium was reported in the Maastrichtian (Schrank, 1984; Schrank et al., 1985) and from Late Campanian-Maastrichtian (El-Beialy, 1995). P. australinium was recorded from the Late Campanian-Late Maastrichtian in Venezuela (Yepes, 2001). Palaeocystodinuim golzowense recorded has its LAD in this palynozone for Dzata-1 well at 2450 m and Dzata-2A well at 2420 m while extending into younger sediments in Lynx-1X well at 2700 m. P. golzowense was documented from Late Paleocene-Early Eocene in Spain (Caro et al., 1975), Campanian-Paleocene in Gabon (Boltenhagen, 1977 and 1980) and Late Campanian-Early Maastrichtian in Israel (Hock et al., 1996). P. golzowense was observed from 66 University of Ghana http://ugspace.ug.edu.gh the Late Campanian-Late Maastrichtian in Venezuela (Yepes, 2001) and in the Early Maastrichtian in Italy (Roncaglia, 2002). Palaeocystodinuim golzowense was reported in the Maastrichtian in Egypt (El Beialy, 1995) and in Ghana (Atta-Peters and Salami, 2004). Kurita and Mclntyre (1995) observed P. golzowense from Canada in the Paleocene and from the Selandian-Ypresian in Russia (Iakovleva et al., 2000). Subzone 1 of palynozone III is restricted to the Early-Late Campanian from 3320 m – 3120 m in Lynx-1X well, 2910 m – 2750 m in Dzata-1 well and 2781 m – 2620 m in Dzata-2A well. Age of subzone: Early-Late Campanian Subzone 2: Dinogymnium acuminatum Interval Zone Definition of subzone: The base of this subzone is defined by the LAD of Odontochitina operculata and the top by the LAD of Dinogymnium spp. Discussion and age assessment: Odontochitina operculata in this subzone last appeared at depths, 3100 m for Lynx-1X well, 2750 m for Dzata-1 well and 2781 m for Dzata-2A well. The FAD of O. operculata was recognized in palynozone II at level 3320 m for Lynx-1X well, 2890 m for Dzata-1 well and 2781 m for Dzata-2A well. In Egypt, O. operculata was recorded from pre-Maastrichtian strata (Urban et al.,1976; Schrank, 1987 and El Beialy, 1993), Late Campanian-Middle Maastrichtian (Schrank and Perch-Neilsen, 1985), Late Campanian (Schrank, 1988), Late Campanian-Early Maastrichtian (Ganz et al., 1990), in the Campanian (Schrank, 1991), Late Cenomanian-Maastrichtian (Schrank and Ibrahim, 1995) and from the Late Campanian-Maastrichtian (El Beialy, 1995). O. operculata was reported in the Early Maastrichtian of the Tano Basin, Ghana (Atta-Peters 67 University of Ghana http://ugspace.ug.edu.gh and Salami, 2004), Late Campanian-Early Maastrichtian in Israel (Hock et al., 1996) and in the Late Campanian in the Netherlands (Herngreen et al., 1996). Wilson (1978) recorded Odontochitina operculata in the Maastrichtian and in the Campanian (Ioannides and McIntyre, 1980) from Canada. In Morocco, O. operculata was documented from the Late Campanian- Early Maastrichtian (Rauscher and Doubinger, 1982). O. operculata occurred worldwide in the Late Campanian and crosses the Campanian-Maastrichtian boundary with the LO in the early part of the Early Maastrichtian (Wilson, 1974; May, 1980; Costa and Davey, 1992; Slimani, 1995, 2001; Williams et al., 2004; Slimani et al., 2016; Guédé et al., 2019). The LAD of Dinogymnium undulosum and Dinogymnium acuminatum were recognized in this palynozone at depths 2760 m for Lynx-1X well, 2450 m for Dzata-1 well and 2420 m for Dzata-2A well. D. undulosum among other Dinogymnium species was documented in Canada from the Campanian-Maastrichtian (Williams et al., 1974), Late Campanian-Maastrichtian in Morocco (Rauscher et al., 1982), Early Maastrichtian in Nigeria (Edet and Nyang, 1994) and from the Late Campanian-Early Maastrichtian in the Netherlands (Herngreen et al., 1996). D. undulosum was recorded from the Santonian-Maastrichtian of America and Europe (Schrank, 1987). D. undulosum was reported from the Cenomanian-late Maastrichtian (Masure et al., 1998) and Cenomanian-Maastrichtian (Boltenhagen, 1977 and 1980). Dinogymnium was recorded in the Early Maastrichtian (Brinkhuis and Zachariasse, 1988; Oboh-Ikuenobe et al., 1998; Slimani et al., 2010; 2016; M'Hamdi et al., 2015; Sanchez-Pellicer et al., 2017). Oboh-Ikuenobe et al. (1998) averred that the last fossil record of Dinogymnium worldwide were found in the Late Maastrichtian rocks, before the Maastrichtian/Danian boundary. Dinogymnium spp. were documented to have their LO in the Maastrichtian (Stover et al., 1996; Costa and Davey1999; Atta-Peters and Salami, 2004) and aided in identifying the Cretaceous-Paleogene (K-Pg) boundary (Williams et al., 1993, 2004). 68 University of Ghana http://ugspace.ug.edu.gh Other important taxa recorded in this subzone includes Glaphyrocysta divaricata, Cordosphaeridium inodes and Adnatosphaeridium multispinosum. G. divaricata was recognized together with Cordosphaeridium inodes in this palynozone at depths 2860 m for Lynx-1X well, 2670 m for Dzata-1 well and 2580 m for Dzata-2A well. Oboh-Ikuenobe et al. (1998) opined that Glaphyrocysta divaricata and Cordosphaeridium inodes recorded had their FAD in the Late Maastrichtian in the Cote d'Ivoire Ghana transform margin. Masure et al. (1998) further reported Glaphyrocysta divaricata from the Late Campanian-Early Paleocene of the CIG transform margin and documented an Early Paleocene age for Cordosphaeridium inodes. Adnatosphaeridium multispinosum was first observed at the end of this palynozone together with the LAD of Dinogymnium spp. A. multispinosum was recorded at depths, 2760 m for Lynx-1X well, 2450 m for Dzata-1 well and 2420 m for Dzata-2A well. A. multispinosum was reported in the Middle Maastrichtian-Paleocene from Ghana (Atta-Peters and Salami, 2004) and in the Maastrichtian age sediments from the IS-3AX well, Tano Basin (Atta-Peters and Salami, 2006). A. multispinosum was also documented from Nigeria in the Paleocene (Masure et al., 1998) and from the Late Paleocene-Eocene (Jan du Chene et al., 1978; Jan du Chene and Adediran, 1984). Edwards (1980) documented A. multispinosum from the Late Paleocene- Early Eocene in Alabama and Georgia, from Late Thanetian-Ypresian in the Netherlands (Herngreen, 1984) and from Venezuela in the Middle Eocene (Helenes et al., 1998). Based on the discussion above, subzone 2 of PZ-III is restricted to the Early-Late Maastrichtian between depth intervals 3100 m and 2760 m in Lynx-1X, 2730 m and 2450 m in Dzata-1 and 2620 m and 2420 m in Dzata-2A. Age of subzone: Early-Late Maastrichtian 69 University of Ghana http://ugspace.ug.edu.gh Recovered dinoflagellates with associated sporomorphs stratigraphic ranges indicates overlap which suggest PZ-III is representative of Campanian-Maastrichtian age. 70 University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Fig. 4.4: Relati ve percentage composition distribution chart of dinocysts (marine palynomorphs) with spores and pollen (terrestrial palynomorphs) in Palynozone III and IV from Lynx-1X well. 71 Palynozone III (Campanian-Maastrichtian) Palynozone IV (Paleocene-Early Eocene) University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Fig. 4.5: Relative percentage composition distribution chart of dinocysts (marine palynomorphs) with spores and pollen (terrestrial palynomorphs) in Palynozone III from Dzata-1 well. 72 University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Fig. 4.6: Relative percentage composition distribution chart of dinocysts (marine palynomorphs) with spores and pollen (terrestrial palynomorphs) in Palynozone III from Dzata-2A well. 73 University of Ghana http://ugspace.ug.edu.gh 4.2.4 Palynozone IV (PZ-IV): Cerodinium diebelli-Apectodinium homomorphum- Homotryblium tenuispinosum Assemblage Zone This zone was recognized only in Lynx-1X well and restricted to the sample depth intervals (2520 – 2740 m) (Figs. 4.4). Palynomorph preservation was good to very good and recovery was generally very good. Terrestrial palynomorphs (sporomorphs) were common in almost all the studied samples in this zone (5-20% of total palynomorphs). Dinoflagellate cysts (80-95%) dominated the total palynomorphs within the palynozone (Fig. 4.4, 4.5 and 4.6). Generally terrestrial palynomorphs decreased up the well within this zone. Definition of Zone: FAD of Apectodinium homomorphum, Diphyes colligerum and LAD of Cerodinium diebelli and Andalusiella polymorpha. Associated Taxa: Andalusiella polymorpha, Spiniferites fluens, Spiniferites membranaceus, Spiniferites hyalospinosus, Hafniasphaera septata, Hafniasphaera hyalospinosa, Cordosphaeridium fibrospinosum, C. delimurum, Fibrocysta lappacea, Areoligera retiintexta, Adnatosphaeridium multispinosum, Hystrichokolpoma granulatum, H. proprium, Turbiosphaera galeata, Phelodinium magnificum, Coronifera oceania, Operculodinium centrocarpum, Lingulodinium machaerophorum, L. hemicystum, L. echinatum, Oligosphaeridium poculum, Senoniasphaera inornata, Alterbidinium, Oligosphaeridium complex, Cribroperidinium, Polysphaeridium subtile, Homotryblium floripes, Homotryblium tenuispinosum, Ifecysta fusiforma, Diphyes bifidium, Damassadinium heterospinosum, D. californicum, Leptodinium subtile, Lejeunecysta hyaline, Areosphaeridium diktyoplokum, Florentinia mantellii, Surculodinium longifurcatum, Selenopemphix nephroides and Achomosphaera spp. Sporomorphs recovered includes Cyathidites, Gleichniidites, Araucariacites australis, Proxapertites cursus and Longapertites marginatus. 74 University of Ghana http://ugspace.ug.edu.gh Remarks: Overall, the interval was characterized by rich palynological assemblages. Palynozone IV is subdivided into three subzones 1-3 which are detailed below; Subzone 1: Andalusiella polymorpha Interval Zone Definition of subzone: The top of this subzone is defined by the LAD of Andalusiella polymorpha and Cerodinium diebelli. Other useful taxa include Diphyes colligerum and Damassadinium californicum. It ranges from 2740 m – 2620 m. Discussion and age assessment: Although some taxa of this zone recovered straddle the Campanian-Maastrichtian/Paleocene, the absence of Dinogymnium spp. was an indication of an age younger than the Maastrichtian as Dinogymnium became extinct at the end of Maastrichtian (Oboh-Ikuenobe et al., 1998; Atta- Peters and Salami, 2004). The LAD of Cerodinium diebelli at level 2620 m and Andalusiella polymorpha at 2640 m was used to define the Danian-Selandian boundary in this subzone. They range from 2760 m - 2620 m in Lynx-1X well. The LAD of Cerodinium diebelli is a good marker for the Danian- Selandian boundary (Powell, 1992; Oboh-Ikuenobe et al., 1998; Masure et al., 1998; Williams et al., 2004; Fensome et al., 2008; Awad and Oboh-Ikuenobe, 2016; Guede et al., 2019). The LAD of Andalusiella spp. (e.g. Andalusiella polymorpha) is also known to be in the Danian and observed in strata from the middle and low latitudes of the northern Hemisphere (Williams et al., 1993; Masure et al., 1998; Oboh-Ikuenobe et al, 1998; Slimani et al., 2016). Damassadinium californicum and Damassadinium heterospinosum first appeared in this palynozone at level 2720 m. D. californicum was documented in the Danian from California (Fensome et al., 1993), Danian-Thanetian in the Atlantic Ocean (East) (Masure et al., 1998; Moullade et al., 1998) and in Early Paleocene in Mexico (Helenes, 1998). D. californicum was 75 University of Ghana http://ugspace.ug.edu.gh reported from the Late Paleocene in South Carolina (Gohn et al., 2000). Damassadinium californicum was observed from Late Maastrichtian-Danian in Venezuela (Pocknall et al., 2001), Late Maastrichtian-Late Selandian in the Southern and Northern Hemisphere (Williams et al., 2004) and Danian in New Jersey (Landman et al., 2004). Diphyes colligerum was first recognized at depth 2720 m and persisted throughout the entire study samples and last occurred at 2580 m. D. colligerum has been reported from the Late Paleocene-Eocene in Australia (Verdier, 1970) and the Late Paleocene-Late Eocene in Canada (Eastern Offshore) (Williams, 1975). D. colligerum was reported from the Late Paleocene- Middle Eocene in the Atlantic Ocean (Brown and Downie, 1984), Paleocene-Eocene in England (Jolley and Spinner 1989). D. colligerum was recorded in the Eocene in Egypt (El- Beialy et al., 1990). This subzone ranges from 2740 m - 2620 m. Age: Danian Subzone 2: Homotryblium tenuispinosum Interval Zone Definition of subzone: The top of this subzone is defined by the FAD of Homotryblium tenuispinosum at 2580 m. Other useful taxa include Apectodinium homomorphum and Ifecysta spp. (Ifecysta fusiforma, Ifecysta pachyderma). Discussion and age assessment: In this subzone, the FAD of Apectodinium spp. is not close to the Selandian-Thanetian boundary but within the Danian. Homotryblium tenuispinosum, H. pallidum and H. floripes were observed in subzone 2 in PZ- IV. FAD of H. tenuispinosum occurred at level 2580 m while H. pallidum and H. floripes occurred earlier at level 2600 m persisted throughout the studied intervals. H. tenuispinosum 76 University of Ghana http://ugspace.ug.edu.gh was reported from the Paleocene-Eocene in England (Downie et al., 1971). Homotryblium tenuispinosum was reported from the Paleocene-Eocene (Caro, 1973). H. tenuispinosum was documented in Virginia from the Late Paleocene-Early Eocene (Edwards, 1996) and in Maryland (Guex et al., 1996). H. tenuispinosum was recorded in the Late Eocene from Egypt (El-Beialy, 1988) and from the Late Paleocene-Early Eocene in Austria (Egger et al., 2003). H. tenuispinosum was documented in the Thanetian in the Dahomey Basin of southwestern Nigeria (Bankole et al., 2007), in Douala Basin, Cameroun (Mbesse et al., 2012) and in Morocco (Slimani et al., 2016). Homotryblium pallidum was documented from the Paleocene-Eocene in England (Downie et al., 1971), in Spain (Caro, 1973) and from the Ypresian-Lutetian in the Netherlands (De Coninck, 1977). Homotryblium sp. similar to H. pallidum in this zone was reported from the late Paleocene-Early Eocene in Maryland and Virginia (Guex and Edwards, 1996). Homotryblium spp. were recorded in the Thanetian in Kazakhstan and southern Tethys (Iakovleva et al., 2001; Crouch et al., 2003) and Thanetian from southwestern Nigeria (Bankole et al., 2007) and in Cameroun (Mbesse et al., 2012). Ifecysta pachyderma and Ifecysta fusiforma were first recognized together at level 2660 m in this palynozone. In Nigeria, Ifecysta pachyderma and Ifecysta were reported from the Late Paleocene-Early Eocene (Jan du Chêne et al., 1984), Ifecysta from the Late Paleocene-Early Eocene (Fensome et al., 1995) and Ifecysta fusiforma documented from the Paleocene-? Earliest Eocene (Antolinez-Delgado and Oboh-Ikuenobe, 2007). The relative high occurrence of Ifecysta spp. (Ifecysta fusiforma, Ifecysta pachyderma and Ifecysta cf. lappacea) through this subzone supports age assignment for Late Paleocene which was reported in other studies in West Africa (Antolinez, 2006; Bankole et al., 2007; Mbesse et al., 2012; Awad and Oboh- 77 University of Ghana http://ugspace.ug.edu.gh Ikuenobe, 2016). Subzone 2 of palynozone range from 2620 m – 2580 m based on the FAD of Homotryblium tenuispinosum. Age: Selandian (Middle Paleocene)-early Thanetian (Late Paleocene) Subzone 3: Apectodinium homomorphum Interval Zone Definition of subzone: The base of the zone is defined by the LAD of Apectodinium homomorphum. This zone is characterized by highest relative abundances of the following taxa: Apectodinium spp., Adnatosphaeridium multispinosum, Cordosphaeridium spp., Homotryblium tenuispinosum, Hystrichokolpoma granulatum, Hafniasphaera spp. and Polysphaeridium spp. Discussion and age assessment: Apectodinium homomorphum was first recognized at depth 2700 m in PZ-IV and had its LAD in this subzone at level 2580m. A. homomorphum was reported in the early Eocene in Canada (Barss et al., 1979) and from Thanetian-Ypresian in Morocco (Prevot et al., 1979). A. homomorphum was documented from Late Paleocene-Early Eocene in Maryland (Edwards, 1996) and in Argentina (Olivero et al., 2001). A. homomorphum was reported in Nigeria in the Late Paleocene-Early Eocene (Jan du Chêne et al., 1978) and in the Early Eocene (Oloto, 1992). A. homomorphum was recorded from the Late Thanetian-Early Ypresian in Netherlands (Herngreen, 1984) and in Morocco (Soncini, 1992). A. homomorphum was also recovered in the Early Eocene from Egypt (El-Beialy et al., 1990), and from early Eocene-Middle Eocene in Alaska (Frederiksen et al., 2002). Apectodinium was documented in the Selandian in Tunisia (Brinkhuis, 1994), in the Late Paleocene from Morocco (Slimani et al., 2016) and from the Côte d'Ivoire-Ghana Transform Margin (Awad and Oboh-Ikuenobe, 2016). 78 University of Ghana http://ugspace.ug.edu.gh The highest relative abundances of Apectodinium spp. recorded in this subzone may be related to the latest Thanetian and earliest Ypresian, within the Paleocene-Eocene thermal maximum (PETM) interval which marks the Paleocene-Eocene transition (Powell, 1992; Bujak and Mudge, 1994; Crouch et al., 2000; Heilmann-Clausen and Egger, 2000; Crouch and Brinkhuis, 2005; Mbesse et al., 2012; Slimani et al., 2016; Awad and Oboh-Ikuenobe, 2016; Oboh- Ikuenobe et al., 2017; Guédé et al., 2019). The FAD of Hafniasphaera septata and Hafniasphaera hyalospinosa were recognized at level 2680 m in this palynozone and increase in abundance in this subzone. H. septata was reported in the Late Paleocene from Australia (Hansen, 1977; Stover et al., 1987) and Early Eocene in Nigeria (Oloto, 1992). H. septata was recorded from the Late Paleocene-Early Eocene in Denmark (Hansen, 1979) and West Germany (Costa et al., 1988; Dill et al., 1996). H. septata was documented in the Paleocene from Georgia (Edwards, 2001). Hystrichokolpoma granulatum first occurred in this palynozone at depth 2680 m. H. granulatum was documented from the Early Eocene-Middle Eocene (Eaton, 1976) and in the Ypresian in England (Islam, 1983). H. granulatum was reported from Ypresian-Lutetian in the Netherlands (De Coninick, 1977) and in the Early Paleocene in Israel (Eshet et al., 1992). In India, H. granulatum was recorded from Late Paleocene-Eocene (Khanna, 1979) and in the Middle Eocene (Mehrotra et al., 2002). H. granulatum was reported in Canada in the Middle Eocene (Head et al., 1989). Cordosphaeridium fibrospinosum was first recognized in this palynozone at level 2700 m. with a high occurrence in this subzone. C. fibrospinosum was observed in England in the Ypresian (Downie et al., 1971) and from Ypresian-Lutetian (Powell, 1992). C. fibrospinosum was documented from the Paleocene-Late Eocene in W. Germany (Gocht, 1969), Middle Paleocene-Early Ypresian in Spain (Caro, 1973), Maastrichtian-Paleocene in Maryland 79 University of Ghana http://ugspace.ug.edu.gh (Benson, 1976), Early Paleocene-Early Eocene in Canada (Brideaux et al., 1976) and in the Early Paleocene in Israel (Eshet et al., 1992). Ifecysta spp., Operculodinium, Glaphyrocysta spp., Apectodinium spp., Polysphaeridium spp and Spiniferites recorded in this palynozone were recorded from the Late Paleocene-Early Eocene in northern Niger Delta (Anambra) Basin, Nigeria (Oboh-Ikuenobe et al. (2017). This subzone is recognized in sample intervals from 2580 m – 2520 m. Age: Thanetian (Latest Paleocene)-Ypresian (Early Eocene) The stratigraphic significant taxa across the entire palynozone (PZ-IV) suggests a Paleocene- Early Eocene age. 80 University of Ghana http://ugspace.ug.edu.gh 4.3 PALEOECOLOGY AND PALEOPROVINCES 4.3.1 Palaeoecological and paleoclimatic implications from sporomorphs The palaeoenvironment was determined based on significant palynomorphs taxa with respect to their ecological inclinations and on the overall extents of palynomorph groups. The Albian- Cenomanian section of the studied wells (Lynx-1X, Dzata-1 and Dzata-2A) yielded abundant well preserved sporomorphs (pteridophytes, gymnosperms and angiosperms) few marine palynomorphs (dinocysts). Sporomorphs are continental in origin with their distribution in marine environments being dependent on wind direction, current patterns in basin and water dispersion. Degree of preservation, level of pollen production and nature of the depositional environment are other factors that determine their distribution in marine environments. Dominant Classopollis spp. recovered in this study supports a deposition in a coastal region (Herngreen, 1973; Herngreen et al., 1982). The Cheirolepidiaceae which are the producers of Classopollis and ephedroids are xerophytic which are semiarid or arid elements (Jardiné et al., 1974). The sporomorphs dominates (99% of palynomorphs) the marine dinoflagellates (1%). This suggests the Albian-Cenomanian sediments of this study were deposited in a semiarid to arid coastal or near shore environment. The fern spores were recorded in low amounts in the nearshore Albian-Cenomanian and ?Turonian-Santonian (Palynozone I and II) sediments of the study. These fern spores (e.g. Deltoidspora, Cyathidites, Cicatricosisporites) have been reported to prefer humid conditions and abundance of pteridophytic fern spores suggests a vegetation that grew on moist biotopes or wetlands (Playford, 1971; Schrank, 1987; Schrank and Mahmoud, 1998; Mahmoud and Moawad, 2002; El Beialy et al., 2011). Infrequent to common occurrences of Inaperturopollenites and Araucariacites documented in palynozone I and II were related with 81 University of Ghana http://ugspace.ug.edu.gh conifer forests and infers deposition in dry hinterlands (Mahmoud and Moawad, 2002; El Beialy et al., 2010). The Campanian-Early Tertiary (Paleocene-Eocene) sediments (Palynozone III and IV) recovered abundant and diverse marine dinoflagellates which dominates over the sporomorphs (spore and pollen). Most of these sporomorphs were documented from the Late Cretaceous- Early Tertiary sediments from the ASA region (Schrank, 1987; El Beialy, 1995; Herngreen et al, (1996). The sporomorphs representatives are dominated by Spinizonocolpites, Proxapertites, Longapertites and Foveotriletes with some triporate (Proteacidites, Echitriporites). Longapertites, Proxapertites and Spinizonocolpites are characteristic elements of the palmae (Muller, 1968; Schrank, 1987; El Beialy, 1995). The term palmae connotes a hot tropical to sub-tropical climate (El Beialy, 1995). According to Germeraad et al. (1968), these taxa are thought to belong to the genus Nypa which flourish in mangrove environments alongside coastal areas of the humid tropics (Schrank, 1998; Herngreen, 1998; El Beialy, 1995). In the Campanian-Maastrichtian, other plants groups such as the green algae (Pediastrum) and Botryococcus were common but increased in abundance in the Paleocene-Eocene. Pediastrum have been found in high abundances in low salinity lakes and transported by fluvial systems into nearshore shelfal situations (Singh et al., 1981; Hutton, 1988). Botryococcus has been reported from ancient lacustrine, fluvial, lagoonal, and deltaic/nearshore marine sediments (Piasecki, 1986; Riding et al., 1991; Williams, 1992; Deaf, 2009). Fresh to brackish water conditions can be inferred from the presence of Botryococcus. Based on dominant sporomorphs (Longapertites, Proxapertites) discussed above, the Campanian-Maastrichtian sediments are suggested to be deposited in a mangrove (brackish) 82 University of Ghana http://ugspace.ug.edu.gh water environments and from brackish to fresh water environment for the Paleocene-Eocene sediments in a hot tropical climate. 4.3.1.1 Paleofloral Provinces Herngreen et al. (1996) established three palynofloral areas within the Cretaceous. These regions appear to be identified with the contemporary latitudinal climatic zones where the tropical or close central Africa-South America (ASA) region occupies. The three provinces are: • The Pre-Albian Early Cretaceous Dicheiropollis etruscus/Afropollis Province. • The Albian to Cenomanian Elaterate Province. • The Senonian Palmae Province The terrestrial microfloras affirms which of the provinces the deposition of the palynozones occurred. 4.3.1.1.1 The Pre-Albian Early Cretaceous Dicheiropollis etruscus/Afropollis Province. The characteristics of this province are; • The predominance of Classopollis and good representation of other gymnospermous pollen, especially Araucariacean and the ephedroid plexus which generally alternate in abundance in the Northern South American and African (except southern) sporomorph associations. • Less common Bisaccate pollen and portrayed by small species with low numbers of spores. • The occurrence of stratigraphically relevant taxa, in a stratigraphic order Dicheiropollis etruscus, Tucanopollis crisopolensis, Afropollis spp. 83 University of Ghana http://ugspace.ug.edu.gh 4.3.1.1.2 Albian-Cenomanian Elaterate Province This palynofloristic area was named Northern Gondwana territory by Brenner (1976) and Galeocornea paleophytogeoprovince by Srivastava (1978). It was later renamed as the Elaterosporites phytogeoprovince by Srivastava (1981). Herngreen and Jimenez (1990) and Dino et al. (1999) studied a new data and averred that the distribution of these elaterates transcends the Africa and South America (ASA) continents as far back as China and Papua- New Guinea. The characteristics of this paleophytogeoprovince are; • Presence of high frequencies elater-bearing taxa, including the genera Elaterocolpites, Elateroplicites, Elateropollenites, Elaterosporites, Galeocornea, Senegalosporites and Sofrepites. • Scarcity of fern spores. A large portion of the spores have a place with the psilatrilete group, Cicatricosisporites or Crybelosporites pannuceus. Numerous other cosmopolitan taxa happen unpredictably and occasionally. • Absence of bi-and trisaccate gymnospermous pollen. Classopollis might be very common. • High rates and a noteworthy morphological diversification of angiospermous pollen grains. Common Afropollis, Cretacaeiporites, Hexaporotricolpites and Triorites (which showed up in the Late Cenomanian) occurred with psilate just as reticulate tricol(por)ate species. Angiospermous pollen represented up to 70% in the low paleolatitude areas by the Late Albian time. • Common ephedroid pollen, for example, Ephedripites, Equisetosporites, Gnetaceaepollenites and Steevesipollenites. This richly diverse and numerous polyplicate group with straight or twisted ridges are characteristic of the Elaterates Province. 84 University of Ghana http://ugspace.ug.edu.gh Palynozone I and II as discussed earlier was deposited in the Albian to Cenomanian Elaterate Province as the sporomorph assemblage conform to the above attributes of Elaterate Province (Herngreen et al., 1996). 4.3.1.1.3 The Senonian Palmae Province Herngreen (1980) established the Late Cretaceous Palmae Province of Africa and South America which was later redefined in greater detail limiting it to the Senonian by Herngreen and Chlonova (1981). The term Palmae Province refers to a hot tropical to sub-tropical climate and the assemblages are suggestive of a warm and humid climate (Herngreen, 1998). The palynozone IV (Paleocene-Eocene) of present study recorded taxa that fit the Senonian Palmae Province. This province is constituted by surge in numbers (10-50%) of monocolpate Palmae types of the Psila-/retimonocolpites plexus. Taxa of the province include the genus of Buttinia, Echitriporites and the monocolpates Longapertites, Mauritiidites, Spinizonocolpites and Proxapertites which are considered to inhabit mangrove environment of the humid tropics. The Campanian-Maastrichtian and Paleocene-Eocene (palynozone III and IV) of the study fits into the Senonian Palmae Province. 4.3.2 Paleoecological and paleoclimatic implications from dinoflagellates Palynozone III and IV are primarily dominated by dinoflagellate cysts in all the studied wells (Lynx-1X, Dzata-1 and Dzata-2A). The gonyaulacoids (53-82% of dinocysts) dominated over the peridinoids (18-47% of dinocysts) in intervals from 3000 – 3300 m in Lynx-1X, gonyaulacoids (50-100%) and peridinoids (0-50%) from 2420 – 2781 m in Dzata-2A, 85 University of Ghana http://ugspace.ug.edu.gh gonyaulacoids (81-100%) and peridinoids (0-19%) from 2450 – 2910 m in Dzata-1 (Fig. 4.7, 4.8 and 4.9). The Albian-Cenomanian (Palynozone I) and ?Turonian-Santonian (Palynozone II) of studied wells are dominated by pollen grains with few dinoflagellates such as Oligosphaeridium complex, Subtilisphaera, Cyclonephelium, Spiniferites ramosus, Odontochitina porifera. Sporomorphs dominated by sphaeroidal pollens supports the deposition in a nearshore/shallow marine environment for this assemblage. According to Davies et al. (1982), there are four categories by which dinoflagellates can be utilized for the recognition of paleoenvironments which includes; • The absolute abundance of dinoflagellates. • The relative abundance of dinoflagellates to other palynomorph types. • Dinoflagellate species variety and dominance. • The dinoflagellate assemblage composition. In this study, the gonyaulacoids taxa in the Campanian-Maastrichtian (PZ-III) are mostly genus of Adnatosphaeridium, Cordosphaeridium, Glaphyrocysta, Areoligera and Spiniferites whilst the peridinoid taxa consists of Andalusiella, Palaeocystodinium, Cerodinium and Phelodinium. The Paleocene-Eocene (PZ-IV) gonyaulacoids are dominated by Spiniferites association which include Polysphaeridium, Homotryblium, Operculodinium, Diphyes in addition to those genera observed in the Campanian-Maastrichtian. Apectodinium was observed in PZ-IV together with the peridinoid taxa in the Campanian-Maastrichtian. Downie et al. (1971) recognized four dinoflagellate cysts-acritarch associations in the Early Eocene rocks of southern England and were named after the genus of the dominant species. These associations are: 86 University of Ghana http://ugspace.ug.edu.gh • Spiniferites (as Hystrichosphaera) Association, which is dominated by species of the genera Achomosphaera, Hystrichosphaeridium, Cordosphaeridium and Spiniferites. • Areoligera Association, dominated by the genera Areoligera and Glaphyrocysta. • Micrhyridium Association, dominated by the genera of acritarch Micrhyridium and Comasphaeridium. • Wetzeliella Association, dominated by the genera Wetzeliella and Deflandrea. They opined that Spiniferites and Areoligera Associations are indicative of open marine environment; Wetzeliella Association indicates lagoonal, estuarine and brackish water environments; Micrhyridium Association suggesting inner neritic depositional environment. Majority of the samples in palynozone III (Campanian-Maastrichtian) are dominated by Spiniferites Association with few being dominated by Areoligera Association while palynozone IV (Paleocene-Eocene) had abundance of both Spiniferites Association and Areoligera Association. Islam (1984) widened the concepts of Downie et al. (1971) and identified several groups such as the Spiniferites assemblage (Achomosphaera, Hystrichosphaeridium, Cordosphaeridium) which is typical of open marine environmental conditions; Adnatosphaeridium, Glaphyrocysta and Areoligera group which are typical of high energy open marine environments; Wetzelielloideae assemblage (Apectodinium, Charlesdowniea, Dracodinium and Wetzeliella) which are normally found in lagoonal, estuarine or brackish environments. The Wetzeliella Association in the present study consists of peridinoids such as Andalusiella, Palaeocystodinium, Cerodinium, Phelodinium and Apectodinium for palynozone IV. In the Campanian-Maastrichtian (Palynozone III) of Lynx-1X well, the gonyaulacoids dominates over the peridinoids from intervals 3140 m – 3300 m which suggests deposition in an outer neritic environment while the intervals 2820 – 3120 m had relatively equal abundance 87 University of Ghana http://ugspace.ug.edu.gh of gonyaulacoids and peridinoids suggesting deposition in an inner-middle neritic depositional environmental conditions (Fig.4.7). The Paleocene-Eocene (Palynozone IV) of Lynx-1X well intervals (2700 – 2740 m) recorded relatively equal abundance of Wetzeliella Association and Spiniferites Association which was replaced by dominant Spiniferites Association from 2680 - 2520 m (Fig. 4.10). In palynozone III, open marine gonyaulacoids (Spiniferites Association) dominated the entire samples of Dzata-1 and Dzata-2A wells which suggests a deposition in an open marine (outer neritic) depositional environment (Fig. 4.8 & 4.9). 88 University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Gonyaulacoids Peridinoids Figure 4.7: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in Palynozone III of Lynx-1X well. 89 University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Figure 4.8: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in Palynozone III of Dzata-1 well. 90 University of Ghana http://ugspace.ug.edu.gh 20 40 60 80 Figure 4.9: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in Palynozone III of Dzata-2A well. Apectodinium in PZ-IV was persistent throughout the studied intervals with relatively high numbers which indicates a warmer paleoenvironments. According to Powell et al. (1996) and Mudge & Bujak (1996), abundance of Apectodinium was identified with the Paleocene/Eocene 91 University of Ghana http://ugspace.ug.edu.gh Thermal Maximum (PETM) in higher amounts which could be utilized to recognize the Thanetian within PZ-IV. Various palynological study of the mid and high latitude localities reported an Apectodinium acme (40% expansion in the dinoflagellate cyst assemblage during the PETM) and related this increment to worldwide climatic warming (Iakovleva et al., 2001; Crouch et al., 2003, 2014; Sluijs and Brinkhuis, 2009). This supports the interpretation of a warmer paleoenvironments for PZ-IV. Palynozone IV of present study was therefore deposited in a middle-outer neritic depositional environment based on recovered dinoflagellate cysts. 20 40 60 80 Figure 4.10: Relative percentage composition of Gonyaulacoids and Peridinoids abundance in Palynozone IV of Lynx-1X well. 92 Palynozone IV (Paleocene-Early Eocene) University of Ghana http://ugspace.ug.edu.gh 93 Figure 4.11: Correlation of lithology, palynozones and depositional environments of Lynx-1X, Dzata-1 and Dzata-2A. University of Ghana http://ugspace.ug.edu.gh 4.3.2.2 Dinoflagellates Provincialism Lentin and Williams (1980) investigated the distribution pattern of Late Cretaceous peridiniacean dinoflagellates cyst from North America, South America and Africa and established three provincial suites. They opined that these suites show regional differentiation rather than local paleoecological control. These suites are; • The Malloy or Tropical-Subtropical suite, constituted by the genera Andalusiella, Cerodinium, Phelodinium and Senegalinium. • The Williams or Warm Temperate suite, with deflandreoid dinoflagellates mainly represented by the genera Alterbidium, Spinidinium, Chatangiella (small to medium sizes) and Isabelidium. • The McIntyre or boreal-arctic suite, characterized by Laciniadinium and Chatangiella (larger taxa). The dinocyst collections recovered in palynozone III and IV demonstrated abundance of the "Malloy suite" taxa, including species of the genera Andalusiella, Cerodinium, Senegalinium and Phelodinium. Based on recovered peridiniacean dinoflagellates cyst in this study, the Late Cretaceous (PZ-III)-Early Tertiary (PZ-IV) fits a Tropical to Subtropical or Malloy suite of Lentin and Williams (1980). The equivalent of Malloy suite was also recognized in the Campanian to Danian sediments from the peri-Mediterranean basin (Brinkhuis and Zachariasse, 1988; Slimani et al., 2016; M'Hamdi et al., 2014), in Cote d'Ivoire and Ghana (Oboh-Ikuenobe et al., 1998; Masure et al., 1998; Sanchez-Pellicer et al., 2017; Guede et al., 2019), in Senegal (Jan du Chene, 1988), in Ghana (Atta-Peters and Salami, 2004), Colombia and Venezuela (Yepes, 2001) and southeastern USA (Firth, 1993; Srivastava, 1995). 94 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 1 1: Senoniasphaera inornata (Drugg, 1970) Stover and Evitt, 1978; Lynx-1X, 2680 m, T46. 2: Lingulodinium echinatum, (Menéndez, 1965) Guerstein et al., 2008. Emend. Guerstein et al., 2008; Lynx-1X, 2520 m, W62. 3, 5: Florentina spp. ; Lynx-1X, 2520 m, T40. 4,6: Diphyes colligerum (Deflandre and Cookson, 1955) Cookson, 1965, emend. Cookson, 1965, emend. Goodman and Witmer, 1985; Lynx-1X, 2520 m, V58. 4: Lynx-1X, 2680 m, O58. 5: Lynx-1X, 2700 m, C48. 7: Diphyes bifidium (Antolinez-Delgado and Oboh-Ikuenobe 2007); Lynx-1X, 2520 m, O63. 8: Lynx-1X, 2520 m, K46. 9: Polysphaeridium zoharyi, (Rossignol, 1962) Bujak et al., 1980; Lynx-1X, 2580 m, M63. 10: Polysphaeridium subtile, Davey and Williams, 1966. emend. Bujak et al., 1980; Lynx-1X, 2520 m, C48. 11: Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967; Lynx-1X, 2520 m, J71. 12: Lynx-1X, 2520 m, J58. 95 University of Ghana http://ugspace.ug.edu.gh PLATE 1 1 2 3 4 5 6 7 8 9 10 11 12 96 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 2 1: Eocladopyxis cf. peniculata, Morgenroth, 1966; emend. McLean, 1976; Lynx-1X, 2580 m, C62. 2: Selenopemphix nephroides, Benedek, 1972 Benedek, 1972. emend. Bujak et al., 1980; Benedek and Sarjeant, 1981; Head (1993); Lynx-1X, 2520 m, S62. 3, 4: Operculodinium centrocarpum, (Deflandre and Cookson, 1955) Wall, 1967; Lynx-1X 2520 m, W42. 4: Lynx-1X, 2520 m, P60. 5: Apectodinium homomorphum, (Deflandre and Cookson, 1955) Lentin and Williams, 1977; Lynx-1X, 2580 m, V56. 6: Apectodinium sp.; Lynx-1X, 2600 m, Y50. 7: Homotryblium pallidum, Davey and Williams, 1966; Bujak et al., 1980; Lynx-1X, 2540 m, W52. 8: Homotryblium floripes, (Deflandre and Cookson, 1955) Stover, 1975; Lynx-1X, 2600 m, O71. 9: Homotryblium cf. tenuispinosum, Davey and Williams, 1966; Lynx-1X, 2600 m, K69. 10, 11, 12: Hafniasphaera septata (Cookson and Eisenack, 1967) Hansen, 1977: Lynx-1X, 2540 m, Z62. 11: Lynx-1X, 2540 m, Y72. 12: Lynx-1X, 2540 m, W49. 97 University of Ghana http://ugspace.ug.edu.gh PLATE 2 1 2 3 4 5 6 7 8 9 10 11 11 98 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 3 1: Cf. Ifecysta lappacea Lynx-1X 2660 m, Q61. 2,3: Turbiosphaera galeata, Eaton, 1976; Lynx-1X, 2560 m and 2540 m, V61 & W46. 4: Hystrichostrogylon; Lynx-1X, 2540 m, T40. 5: Hystrichokolpoma proprium (Marheinecke, 1992) Fauconnier and Masure, 2004; Lynx-1X, 2720 m, Q46. 6: Hystrichokolpoma granulatum, Eaton, 1976; Lynx-1X, 2540 m, W42. 7: Damassadinium sp. Lynx-1X, 2560 m, S54. 8: Damassadinium heterospinosum (Matsuoka, 1983) Fensome et al., 1993; lynx-1X, 2560 m, W58. 9: Damassadinium californicum, (Drugg, 1967) Fensome et al., 1993; Lynx-1X, 2560 m, M61. 10, 11: Ifecysta cf. fusiforma, Antolinez-Delgado and Oboh-Ikuenobe, 2007; Lynx-1X, 2660 m, H56. 12: Areosphaeridium diktyoplokum, (Klumpp, 1953) emend. Eaton, 1971; emend. Stover and Williams, 1995; Lynx-1X. 2620 m, Y47. 99 University of Ghana http://ugspace.ug.edu.gh PLATE 3 100 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 4 1: Leptodinium sp. cf. subtile Klement 1960; Lynx-1X, 2600 m, U62. 2: Leptodinium subtile, Klement 1960; Lynx-1X, 2600 m, S50. 3: Diphyes colligerum; Lynx-1X, 2620 m, Q53. 4: Fibrocysta lappacea (Drugg, 1970) Stover and Evitt, 1978; Lynx-1X, 2700 m, S57. 5: Diphyes bifidum, Antolinez-Delgado and Oboh-Ikuenobe, 2007; Lynx-1X, 2660 m, T20. 6: Florentina cf. mantellii; Dzata-2A, 2600 m, S6. 7: Florentinia mantellii (Davey & Williams 1966) Davey and Verdier 1973; Dzata-2A, 2580 m, T56. 8: Florentinia cooksoniae, (Singh, 1971) Duxbury, 1980. emend. Duxbury, 1980; Dzata-1, 3150 m, V48. 9: Florentinia laciniata; Dzata-2A, 2600 m. 10: Florentinia sp.1; Dzata-1, 2850 m. 11: Exochosphaeridium sp.; Lynx-1X, 2700 m, C49. 12: Xenascus ceratioides, (Deflandre, 1937) Lentin and Williams, 1973; Lynx-1X 2860 m, K54. 101 University of Ghana http://ugspace.ug.edu.gh PLATE 4 102 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 5 1: Exochosphaeridium? arnace; Lynx-1X, 3180 m, S43. 2: Leberidocysta sp.; Lynx-1X, 2860 m, U62. 3: Senoniasphaera inornata, (Drugg, 1970) Stover and Evitt, 1978; Lynx-1X, 2720 m, Q46. 4, 5, 6: Glaphyrocysta spp.; Lynx-X, 2660 m; M38. 5: Lynx-1X, 2640 m, Y49, S47. 7: Glaphyrocysta semitecta (Bujak et al., 1980) Lentin and Williams, 1981; Lynx-1X, 2640 m, S39. 8: Glaphyrocysta ordinata (Williams and Downie, 1966) Stover and Evitt, 1978; Lynx-1X, 2640 m, X58. 9: Glaphyrocysta retiintexta (Cookson, 1965) Stover and Evitt, 1978; Lynx-1X, 2640 m, J59. 10: Areoligera sp.1; Lynx-1X, 2640 m, W64. 11: Areoligera sp.2; Lynx-X, 2640 m, W64, D41. 12: Adnatosphaeridium multispinosum, Williams and Downie 1966; Lynx-1X, 2560 m, R44. 103 University of Ghana http://ugspace.ug.edu.gh PLATE 5 104 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 6 1,2, 3, 4: Adnatosphaeridium multispinosum, Williams and Downie 1966; Lynx-1X, 2560 m, (C52 & V45). 3,4: Lynx-1X, 2540 m, (Y60 & S50). 5,6: Cordosphaeridium inodes (Klumpp) Eisenack 1963; Lynx-1X, 2540 m, (R43 and G48). 7: Surculodinium longifurcatum; Lynx-1X, 2680 m, T59. 8: Cordosphaeridium fibrospinosum, Davey and Williams, 1966; Lynx-1X, 2640 m, W67. 9: Achomosphaera cf. verdieri; Lynx-1X, 2640 m, V53. 10: Odontochitina porifera, Cookson, 1956; Lynx-1X, 3360 m, X49. 11: Oligosphaeridium cf. poculum; Dzata-1, 3030 m, D45. 12: Spiniferites sabulus, Lynx-1X, 2760 m, Q46. 105 University of Ghana http://ugspace.ug.edu.gh PLATE 6 106 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 7 1,2,3: Oligosphaeridium complex (White, 1842) Davey and Williams, 1966; Lynx-1X, 3220 m, (L55 and K46). 1: Dzata-2A, 3063 m, P54. 4,5: Spiniferites ramosus; Lynx-1X, 2540 m, (H43 and D49). 6, 7, 8: Achomosphaera spp.1; Lynx-1x, 2540 m, W45. 7: Lynx-1X, 2520 m, Y52. 8: Lynx-1X, 2520 m, Q61. 9, 10, 11: Spiniferites spp.; Lynx-1X, 2520 m, P69. 10: Lynx-1X, 2520 m, G60. 11: Lynx-1X, 2540m, V50. 107 University of Ghana http://ugspace.ug.edu.gh PLATE 7 108 University of Ghana http://ugspace.ug.edu.gh PLATE 8 1: Spiniferites fluens (Hansen, 1977) Stover and Williams, 1987; Lynx-1X, 2540 m, R46. 2: Spiniferites fluens (Hansen, 1977) Stover and Williams, 1987; Lynx-1X, 2560 m, J64. 3: Spiniferites hyalospinosus (Hansen, 1977) Stover and Williams, 1987; Lynx-1X, 2540 m, R47. 4: Spiniferites bulloideus (Deflandre and Cookson, 1955) Sarjeant, 1970; Lynx-1X, 2540 m, K46. 5, 6: Spiniferites cf. mirabilis (Rossignol, 1964) Sarjeant, 1970; Lynx-1X, 2540 m, V68. 7: Spiniferites membranaceus (Rossignol, 1964) Sarjeant, 1970; Lynx-1X, 2640 m, O45. 8: Lynx-1X, 2660 m, G52. 9: Spiniferites cf. membranaceus (Rossignol, 1964) Sarjeant, 1970; Lynx-1X, 2640 m, H50. 10: Spiniferites ellipsoideus, Matsuoka, 1983; Lynx-1X, 2640 m, J39. 11: Spiniferites katatonos Corradini, 1973; Lynx-1X, 2540 m, P52. 12: Trichodinium castanea (Deflandre, 1935) Clarke and Verdier, 1967; Lynx-1X, 2980 m, O64. 109 University of Ghana http://ugspace.ug.edu.gh PLATE 8 110 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 9 1: Trichodinium boltenhagenii (Fauconnier and Masure, 2004). emend. Fauconnier and Masure, 2004; Dzata-2A, 2742 m, D52. 2: Trichodinium cf. boltenhagenii (Fauconnier and Masure, 2004). emend. Fauconnier and Masure, 2004; Dzata-2A, 2742 m. O53. 3: Cyclonephelium brevispinatum (Millioud, 1969) Below, 1981; Lynx-1X, 2980 m, P46. 4: Cyclonephelium brevispinatum (Millioud, 1969) Below, 1981; Lynx-1X, 2980 m, T41. 5: Cyclonephelium vannophorum Davey 1969; Lynx-1X, 2940 m, U43. 6: Cyclonephelium distinctum Deflandre and Cookson, 1955; Dzata-1, 2850 m, M52. 7: Circulodinium distinctum (Deflandre and Cookson, 1955) Jansonius, 1986; Dzata-1, 2850 m, J40. 8: Impletosphaeridium sp.1; Lynx-1X, 3200 m, G58. 9: Isabelidium sp. Dzata-1, 2850 m, S63. 10: Isabelidium sp.; Dzata-2A, 3710 m, M48. 11: Subtilisphaera perlucida (Alberti 1959) Jain and Millepied, 1973; Dzata-2A, 4050 m, F61. 12: Andalusiella gabonensis (Stover and Evitt, 1978) Wrenn and Hart, 1988; Lynx-1X, 2760 m, V45. 111 University of Ghana http://ugspace.ug.edu.gh PLATE 9 112 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 10 1: Andalusiella polymorpha; Lynx-1X, 3280 m, H70. 2: Andalusiella sp.; Lynx-1X, 2800 m, V46. 3: Cerodinium boloniense, (Riegel, 1974) Lentin and Williams, 1989; Dzata-1, 2630 m, T65. 4: Phelodinium cf. kozlowskii; Dzata-2A, 2600 m, R49. 5, 6: Cerodinium obliquipes (Deflandre and Cookson, 1955) Lentin and Williams, 1987; Dzata- 1, 2850 m, W50. 6: Dzata-1, 2830 m, S61. 7: Senoniasphaera cf. lordii (Cookson and Eisenack, 1968) Lentin and Williams, 1976; Lynx- 1X, 3040 m, F60. 8: Apteodinium cf. apiatum McIntyre and Brideaux, 1980; Lynx-1X, 2580 m, W58. 9: Palaeocystodinium sp.1; Lynx-1X, 2720 m. 10: Palaeocystodinium golzowense Alberti, 1961; Dzata-2A, 2580 m, N62. 11: Palaeocystodinium cf. lidiae (Górka, 1963) Davey, 1969; Lynx-1X, 2720 m, H48. 12: Palaeocystodinium australinium (Cookson) Lentin and Williams 1976; Lynx-1X, 2720 m, C50. 113 University of Ghana http://ugspace.ug.edu.gh PLATE 10 114 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 11 1: Cerodinium diebelii (Alberti, 1959) Lentin and Williams, 1987; Lynx-1X, 2760 m, C61. 2: Palaeocystodinium golzowense Alberti, 1961; Lynx-1X, 2680 m, H41. 3: Palaeocystodinium cf. rafii Antolinez-Delgado and Oboh-Ikuenobe, 2007; Dzata-1, 2590 m, K61. 4: Odontochitina porifera, Cookson, 1956; Dzata-1, 2610 m, G42. 5: Odontochitina operculata (Wetzel, 1933) Deflandre and Cookson, 1955; Dzata-1; 2650 m, Q64. 6: Dinogymnium albertii, Lynx-1X, 2980 m, D58. 7, 8: Dinogymnium acuminatum; Lynx-1X, 3180 m, G42. 8: Dinogymnium acuminatum; Dzata-2A, 2700 m, H54. 9: Dinogymnium longicorne; lynx-1X, 3180 m, M46. 10: Dinogymnium denticulatum, Evitt, Clarke et Verdier 1973; Dzata-2A, 2720 m, N58. 11: Dinogymnium cf. westralium (Cookson and Eisenack) Evitt et al., 1967; Dzata-1, 2870 m, P54. 12: Dinogymnium cf. undulosum, Cookson and Eisenack, 1970; Dzata-1, 2890 m, H38. 13; Dinogymnium acuminatum; Dzata-1, 2850 m, W62. 115 University of Ghana http://ugspace.ug.edu.gh PLATE 11 116 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 12 1: Dinogymnium denticulatum, Evitt, Clarke et Verdier 1973; Lynx-1X, 3160 m, L44. 2: Dinogymnium acuminatum; Lynx-1X, 3000 m, D50. 3: Dinogymnium sp.1; Dzata-1, 2830 m, L52. 4: Dinogymnium sp.2; Dzata-1, 2900 m, K62. 117 University of Ghana http://ugspace.ug.edu.gh PLATE 12 118 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 13 1: Deltoidspora minor (Couper) Pocock 1970; Lynx-1X, 3000 m, M54. 2: Triplanosporites cf. giganteus; Lynx-1X, 3000 m, X62. 3: Dictyophyllidites harrisii Couper, 1958; Dzata-1, 2830n, W43. 4: Foveotriletes margaritae (Van der Hammen) Germeraad, Hopping and Muller 1968; Lynx- 1X, 2860 m, N44. 5:? Araucariacites; Lynx-1X, 2520 m, P48. 6: Retimonocolpites sp.; Dzata-1, 2850 m, Q60. 7: Monosulcites sp.; Lynx-1X, 2760 m, N52. 8: Monosulcites sp.; Lynx-1X, 2760 m, K65. 9: Tricolpites confessus, Stover and Partridge 1973; Dzata-2A, 2742 m, S42. 10: Proteacidites sp.; Dzata-1, 2850 m, U55. 11: Echitiporites trianguliformis; Dzata-1, 2850 m, V40. 12: Triporate sp.; Lynx-1X, 3000 m, X67. 13: Uvaesporites sp., Dzata-1, 2630 m, U45. 14: Proxapertites operculata; Lynx-1X, 2560 m, W50. 15: Proxapertites sp; Lynx-1X, 3000 m, R55. 16, 17: Proxapertites cursus Van Hoeken-Klinkenberg, 1966; Dzata-1, 2810 m, P55. 17: Dzata-1, 2850 m, H44. 18: Longapertites sp.1; Lynx-1X, 3000 m, M46; x630. 19, 20, 21: Longapertites marginatus, van Hoeken-Klinkenberg, 1964; Lynx-1X, 2760 m, T40. 20: Lynx-1X, 2760 m, N60. 21: Lynx-1X, 3040 m, S64. 22:? Zlivisporis sp.; Lynx-1X; 2980 m, L52. 23: Inaperturopollenites sp.; Dzata-2A, 3450 m, N50. 119 University of Ghana http://ugspace.ug.edu.gh 24: Cicatricosisporites brevilaesuratus Couper, 1958; Dzata-2A, 3450 m, E46. 25: Classopollis cf. brasiliensis Herngreen, 1975; Lynx-1X, (3690 – 3700 m), V50. 26, 27, 28: Classopollis spp.; Dzata-1; 3470 m, V60. 120 University of Ghana http://ugspace.ug.edu.gh PLATE 13 121 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 14 1, 2: Classopollis classoides, Pflug, 1953; Dzata-1, 3410 m, P49. 3: Tetrad of Classopollis torosus, Burger 1965; Dzata-1, 3410 m, G48. 4: Classopollis martinotti; Dzata-1, 3070 m, F70. 5: Cretacaeisporites cf. polygonalis (Jardiné et Magloire) Herngreen, 1973; Dzata-2A, 2841 m, C42. 6: Ephedripites barghoornii (Pocock, 1964); Dzata-2A, 3450 m, Q50. 7, 8: Ephedripites jansonii; Dzata-2A, 3294 m, L63 and U48. 9, 10, 11, 12, 13: Ephedripites spp.; Dzata-1, 3090 m, G40. 10: Lynx-1X, (3710 – 3720 m), C54. 11, 12, 13: Dzata-1, 3410 m; X64. 14, 15: Galaeocornea causea Stover, 1963; Dzata-2A, 2943 m, M47. 16: Afropollis jardinus Doyle et al., 1982; Dzata-1, 3470 m, Y60. 17, 18: Afropollis kahramanensis Ibrahim & Schrank, 1995; Dzata-1, 3470 m, Y67. 18: Dzata-1, 3470 m, L63. 19: Elaterosporites klaszii (Jardiné and Magloire) Jardiné, 1967; Dzata-2A, 2943 m, N50. 20: Elaterosporites verrucatus (Jardiné´ and Magloire) (Jardiné´, 1967); Dzata-2A, 2943 m, V41. 21: Elateroplicites africaensis, Herngreen 1973; Dzata-2A, 3294 m, T68. 122 University of Ghana http://ugspace.ug.edu.gh PLATE 14 123 University of Ghana http://ugspace.ug.edu.gh EXPLANATION OF PLATE 15 1: Elateroplicites africaensis, Herngreen 1973; Dzata-2A, 3294 m, U52. 2: Sofrepites sp.; Dzata-2A, 3333 m, P70. 3: Sofrepites legouxae (Jardiné, 1967); Dzata-2A, 3412 m, V46. 4, 5, 6, 7 : Elaterocolpites castelaini, Jardine´ et Magloire, 1965; Dzata-1, 3950 m, R40, U56. 6, 7: Dzata-2A, 3730 m, W48. 8: Araucariacites australis (Cookson, 1947, ex. Couper, 1953); Dzata-2A, 3210 m, T44. 124 University of Ghana http://ugspace.ug.edu.gh PLATE 15 1 2 3 4 5 6 7 8 125 University of Ghana http://ugspace.ug.edu.gh CHAPTER FIVE PALYNOFACIES ANALYSIS AND PALAEOENVIRONMENTAL INTERPRETATIONS 5.1 INTRODUCTION Muller (1959) established that, the distribution patterns of palynomorphs and other particulate organic matter (POM) can be used for facies recognition and palaeogeographic reconstruction. The term palynofacies was introduced by Combaz (1964) to describe the quantitative and qualitative palynological investigation of the total particulate organic matter assemblage. He further explained the term to encompass the total complement of acid-resistant organic matter recovered from a sediment or sedimentary rock by palynological processing techniques, using hydrochloric acid and hydrofluoric acid, as observed under a microscope. Different definitions for palynofacies have been assigned by different authors. Hughes and Moody-Stuart (1967) described the term palynological facies in a similar manner as "palynofacies" of Combaz (1964) to include all organic elements. Batten (1973) in his definition applied the term palynofacies to refer to the general aspect of kerogen preparation. Quadros (1975) used words Organopalynology and Organopalynofacies for the study of organic matter in sedimentary rocks. Batten (1982a, 1982b) used this concept for the determination of thermal maturity and source potential investigations in addition to palaeoenvironmental and biostratigraphic studies. According to Boulter and Riddick (1986), palynofacies analysis is the study of particulate organic matter assemblages concerned with changes in the relative abundance of various types of organic debris such as palynomorphs, zooclasts, phytoclasts and amorphous organic matter (AOM). Traverse (1988) characterized palynofacies as "the collection of palynomorphs taxa in a portion of a sediment, representing local environmental conditions and not typical of the 126 University of Ghana http://ugspace.ug.edu.gh regional palynoflora”. Powell et al. (1990) redefined the term as “a distinctive assemblage of HCl and HF insoluble particulate organic matter (palynoclasts) whose components mirror a particular sedimentary environment”. Tyson (1993) published a spearheading contribution in the area of palynofacies analysis and averred that the compositional changes in palynofacies are helpful in palaeoenvironmental interpretations of sedimentary rocks as such changes are the result of the interaction of several parameters (for example terrestrial versus marine palynomorph influx, source and rate of sediment influx, water salinity, depth and oxygen concentrations, etc.) within a given depositional environment. Traverse (1994) disclosed that since 1960 the term palynofacies was used to refer to a more or less local concentration of particular palynomorphs, showing a sort of biofacies. Traverse (1994) pointed out that the application of the word has since been geologically oriented, and palynofacies is used essentially to indicate information about the enclosing rock, particularly its environment of deposition which should be called palynolithofacies. Tyson (1995) introduced the modern concept of palynofacies and defined it as ‘‘a body of sediment containing a distinctive assemblage of palynological organic matter thought to reflect a specific set of environmental conditions or to be associated with a characteristic range of hydrocarbon-generating potential” which is dependent on the total assemblage of particulate organic matter. Based on this definition, Tyson (1995) referred to palynofacies as an incredible analytical tool which when utilized alongside geological and geophysical information could be utilized in various investigations of geology (stratigraphy, sedimentology and palaeoenvironmental investigations), palaeontology (biostratigraphic studies), petroleum exploration, environment studies etc. 127 University of Ghana http://ugspace.ug.edu.gh Mendonça Filho (1999) referred the term palynofacies to the investigation of the particulate organic matter present in sediments and sedimentary rocks utilizing the organic matter isolation strategies for sample preparation (kerogen concentration) and applying microscopy techniques as principal tool for acquiring data and statistical methods for its interpretation. According to Mendonça Filho et al. (2012), palynofacies analysis comprises the integrated investigation of all aspects of the kerogen assemblage which incorporates the identification of the individual particulate components, evaluation of their absolute and relative distribution and preservation states. The palaeoenvironmental interpretations introduced for each palynofacies type is dependent on the quantitative analysis of selected palynomorph constituents and total POM, which are known to have a palaeoenvironmental implications. These incorporate terrestrially derived palynomorphs, for example, miospores (e.g. pteridophyte spores, gymnosperm pollen, angiosperm pollen etc.), and aquatic phytoplankton (for example dinoflagellate cysts). Furthermore, there might be terrestrially derived phytoclasts, which can be represented by black wood (inertinite/charcoal), brown wood (e.g. tracheids), plant cuticle and membranous tissues. Minor constituents present include microforaminiferal test linings and freshwater green algae. Some sporomorphs are markers of distinct ecological parameters and along these lines permit not just a potent distinguishing proof of palaeoclimatic conditions but additionally grant reconstruction of the vegetation developing on the source regions. 5.1.1 Classification of Palynofacies Constituents Various classifications have been proposed by many palynologists for palynofacies constituents (e.g. Batten, 1973; Bujak et al., 1977; Masran and Pocock, 1981; Boulter and Riddick, 1986; Hart, 1986; Tyson, 1993 and 1995; Batten, 1996; Mendonça Filho, 1999; 128 University of Ghana http://ugspace.ug.edu.gh Mendonça Filho et al., 2010, 2012) based on degradational state and biological derivatives (i.e., plant fragments, phytoplankton, etc.). Notwithstanding, the different classification schemes are as yet not standardized after numerous studies considering degradational state and natural subordinates (i.e., plant sections, phytoplankton). Staplin (1969) classified two main groups of sedimentary organic matter i.e. ‘Primary materials’ and ‘Modified materials’. The primary materials consist of cuticles, sporomorphs, lignified wood fragments, charcoal, resins, freshwater plankton and marine organisms. Modified materials on the other hand comprises of unorganized amorphous sapropelic material further divided into Sapropel A and sapropel B. Bujak et al. (1977) characterized the four principal kinds of organic particles which are; (1) amorphogen (amorphous: structureless organic matter), (2) phryogen (non-woody plant material, including palynomorphs), (3) hylogen (from woody material) and (4) melanogen (opaque organic matter). Amorphogen and phryogen are more likely to give liquid hydrocarbons in time although hylogen and melanogen are most drastically averse to be produce gas. Hart (1986) categorized organic particles into phytoclasts (includes miospores, megaspores, wood and cuticle fragments; protistoclasts which includes algae, dinocysts, acritarchs and microforaminiferal linings; zooclasts (i.e. arthropod, graptolite, and chitinozoans debris) and receptoclasts (inorganic or organic particles that are areas of precipitation or localization of organic chemical). Pocock et al. (1988) divided organic matter into the following classes: Terrestrial sourced materials (Structured and Biodegraded), Fusinites and Inertinites, Fungi (Sclerotinite), Resins (Resinite), Amorphous and Structured aqueous materials. They discussed Amorphous and Structured aqueous materials with reference to their environmental view point and as a source material for the production of fossil hydrocarbons. Another scheme 129 University of Ghana http://ugspace.ug.edu.gh utilized to categorize the sedimentary organic matter (SOM) was proposed by (Steffen and Gorin 1993; Pittet and Gorin 1997; Bombardiere and Gorin 1998) and summarized in table 5.1. Tyson (1993, 1995) identified three main groups of morphologic components of organic matter (palynofacies) assemblage namely; palynomorphs (organic walled constituents that remain after maceration using HCl and HF acids), phytoclasts (tissues fragments derived from higher plants or fungi) and amorphous organic matter-AOM (structureless material derived from non- fossilizing algae, phytoplankton or bacterially derived AOM, higher plants resins). Table 5.1: Classification of the sedimentary organic matter (after Steffen and Gorin 1993; Pittet and Gorin 1997; Bombardiere and Gorin 1998). Origin Group Constituent Continental Phytoclasts Opaque to semi Equidimensional (Allocthonous) opaque Blade shaped Translucent Miospores Pollen Bisaccate Non saccate Spores Marine Amorphous Non-fluorescent (Autochthonous) Organic matter Fluorescent Microplankton Dinoflagellate cysts Acritarchs Algae Microforaminiferal linings test (MFLT) Batten (1996) classified palynological matter into Palynomorphs, Structured Organic Matter and Unstructured Organic Matter and stated the constituents of the classification as mentioned below; (a): Palynomorphs (spores and pollen grains; fungal sclerotia, spores, fruiting bodies and other reproductive parts; dinoflagellate cysts; Acritarchs; Prasinophyceae algae; Chlorococcalean algae; zygnemataceae and other green alga; cyanobacteria; foraminiferal linings; chitinozoans; scolecodonts; miscellaneous). 130 University of Ghana http://ugspace.ug.edu.gh (b): Structured Organic Matter (STOM) incorporates: I. Phytoclasts (Wood (black and brown); Charcoal and other black phytoclasts; Cuticles; Bark and cork; Other (non-cuticular) tissues; Tubes, filaments and hairs; Fungal hyphae), II. Zooclasts. (c): Unstructured Organic Matter (USTOM) which includes: (Amorphous organic matter; AOM of terrestrial derivation; AOM of aquatic region; gelified matter; resin and amber; solid bitumen). (d): Reworked organic matter. Oboh-Ikuenobe et al. (1997) also proposed a classification technique in which twelve types of organic matter were identified and summarized in table 5.2. Tyson (1995) opined that, the main objectives of palynofacies investigations are to assess the origin of the organic matter (regarding its botanical precursors), relative percentages and preservation of the various constituents, generation of hydrocarbons, fluctuating degree of thermal alteration (maturity) of the organic matter, nature of the deposition palaeoenvironment (terrestrial inputs), reducing versus oxidizing conditions and differentiation of fresh water, brackish or marine environments in terms of palaeosalinity. Nonetheless, the scheme adapted in the study follows the classification scheme of Tyson (1993, 1995) which gives detail palynological classification of individual palynofacies constituents which is dependent on an unadulterated palynological terminology for palaeoenvironmental investigations utilizing transmitted light microscopy. Constituents of kerogen mainly recognized in the study are based on the classification schemes proposed by Tyson (1993, 1995) which identified three main groups within the kerogen assemblage. These are; Amorphous organic matter (AOM), Phytoclasts (translucent and opaques) and Palynomorphs. According to Tyson’s (1995) classification of palynofacies constituents, palynological organic matter components can either be structureless or structured palynological organic matter. 131 University of Ghana http://ugspace.ug.edu.gh Table 5.2: Organic Matter Classification in sediments (after Oboh Ikuenobe et al. 1997). Palynodebris Characteristics Size (μm) Amorphous organic Structureless, irregularly shaped, yellowish-amber to Variable matter brown masses: usually gel-like Marine palynomorphs Dinoflagellates, acritarchs and chitinous inner linings of 30-90 foraminiferal tests Algae Aquatic algal remains mainly Pediastrum 20-70 Resins Unstructured amber-colored exudates, mainly from stem Variable tissues Black debris Opaque particles with sharp angular outlines: lath- 20->200 shaped, or in some cases more equidimensional Yellow-brown frag- Structureless particles of yellow to light brown color: 5-80 ments attributable to highly degraded herbaceous material (leaf mesophyll?) Black-brown frag- Unstructured dark brown to nearly black particles: Variable ments attributable to highly degraded woody material Cuticle fragments Platy epidermal-patterned fragments of waxy cuticle 30->200 coating leaves, stems and roots: pale yellow to light brown in color Plant tissues All other herbaceous material including parenchyma Variable Wood Light to dark brown particles with sharp angular edges 30->200 and/or discernible cellular structure: mainly lath-shaped Sporomorphs Land plant spores and pollen dispersed by water into 10-80 continental and marine environments Fungi Fungal remains such as spores, hyphae and mycelia 5->100 5.1.2 Structureless organic matter Structureless organic matter includes materials such as amorphous organic matter (AOM), resin, and humic gel. The Amorphous Organic matter (AOM) refers to structureless dispersed particulate organic matter (kerogen) whether of marine or non-marine origin. According to Tyson (1995), structureless organic matter is an organic matter that lacks a definite internal structure when observed utilizing light microscopy, lacks a distinct and recognizable outline, and which does not infer its biological affinity. It is basically produced by biodegradation of algal 132 University of Ghana http://ugspace.ug.edu.gh phytoplankton blooms, gotten from zooplankton faecal pellets, or got from biodegradation of cyanobacteria and thiobacteria (Tyson, 1995; Mendonça Filho et al. (2010, 2012). According to Lewan (1986), carbon isotope evidence showed that all the typical AOM in ancient marine basinal fine-grained sediments were ultimately derived from phytoplankton or bacteria. Tyson (1995) further stated that, in mass terms, nearly all fossilized marine organic matter is represented by AOM. The principal control on the appearance of AOM is its preservation state so during degradation it turns out to be progressively more dull (greyish in colour), less cohesive and less resistant to palynological oxidation treatment and heterogenous when viewed under fluorescence (Tyson, 1989). AOM concentrations has also been utilized to demonstrate oxygenation (reducing or oxidizing) conditions of bottom water in ancient sedimentary depositional environments. The high relative or absolute abundances of AOM was usually associated with sediments beneath upwelling water masses and taken to indicate bottom water of low (dysoxic) oxygen concentrations (Davey and Rogers, 1975; Tissot and Pelet, 1981; Summerhayes, 1983). AOM has been found to decline in shallow shelf sediments and increase in a basinward direction, in darker-coloured, organic-rich facies with dysoxic-anoxic conditions (e.g. Dow and Pearson, 1975; Bujak et al., 1977). According to Masran and Pocock (1981), the typical oil-prone AOM preserved under reducing conditions is colourless to neutral grey and referred to it as ‘grey amorphous’. This was differentiated from ‘yellow-amber amorphous’ attributed to amorphous material derived from dominantly terrestrially derived materials. According to Langenheim (1969) and Larsson (1978) resins are the products of higher plants mainly trees, which occupy tropical to subtropical lowland forests and typically gets preserved in waterlogged environments such as ombrogenous mires. Their shape and colour varies from yellow, orange, red rounded globules with angular, conchoidal or irregular surface fractures 133 University of Ghana http://ugspace.ug.edu.gh (Larsson, 1978). Resin is a highly resistant and known in ancient sediments as amber and is mainly produced by coniferous gymnosperms and to a small degree by dicotyledonous angiosperm trees (e.g. Tyson, 1995). Masran and Pocock (1991) suggested the high frequency of resins to be generally accumulated along prodeltaic-deltaic setting. They may also show up more common in non-marine settings (Oboh, 1992). Globules of the resins often come across in organic residues turn out as transparent bodies displaying conchoidal fractures. They are good source of liquid hydrocarbons (Pocock et al., 1988). The biodegradation of the root and bark tissues of land plants produces humic gels, where these tissues were initially released from the plant roots and bark by destructive oxidation. Humic gels are considered as inconsequential contributors to AOM in ancient marine sediments (Tyson, 1995). Table 5.3 and 5.4 shows the classification system of the individual palynological components based on Tyson (1995), which demonstrate the proper use of the classification for the examination of kerogen under transmitted white light. Table 5.3: Phytoclast and Amorphous Groups (After Tyson, 1995). Group Subgroup Opaque phytoclast (black wood) Phytoclast Translucent phytoclast (brown wood) ‘AOM’ Phytoplankton or bacterially-derived amorphous organic matter (traditionally referred to as ‘AOM’) Amorphous Organic matter Resin Derived mostly from higher plants Amorphous products Products of the diagenesis of macrophyte tissues 134 University of Ghana http://ugspace.ug.edu.gh 5.1.3 Structured organic matter (Table 5.3 and 5.4) Structured organic matter is made of discrete and recognizable individuals or colonial entities (i.e. palynomorphs) and plant or animal fragments (i.e. phytoclasts, zooclasts) that show their biological affinities Tyson (1995). Palynomorphs can for the most part be assigned botanical or zoological affinities, whereas phytoclast particles with coherent, angular to irregular outlines that may show some internal structures can be attributed at least to a type of larger plant (i.e. phytoclasts) or animal (i.e. zooclasts) debris. 5.1.3.1 Phytoclasts (Translucent and Opaques (black debris)): Bostick (1971) introduced the term ‘phytoclast’ to portray all particles with size clay or fine- sand derived from higher plants or fungi. They are parts of tissues got from higher plants or fungi and its autofluorescence relies upon derived tissue. Phytoclasts can be translucent (nonopaque) or opaque (black) and non-biostructured, biostructured, structured or ‘pseudoamorphous’ (Mendonça Filho et al.,2012). Translucent phytoclasts (non-opaque phytoclasts): Wood tracheids are one of the most widely recognized members of the biostructured translucent phytoclasts. The bulk of dispersed wood phytoclasts gets preserved in sediments in changing conditions of preservation with their cellular structures decaying after burial (Oboh-Ikuenobe et al., 1999). Their high relative and absolute abundances in antique marine sediments are known to show strong terrestrial influx, with deposition in nearshore proximal settings (for example fluvio-deltaic systems) that were near the parent land plants (Müller, 1959; Pocklington and Leonard, 1979). Hydrodynamic equivalence of woody phytoclasts controls their distribution in sediments, as woody phytoclasts are made of relatively large and dense particles, their high concentrations have usually been found to correlate to coarse silts and very fine sands (Habib, 1983; Firth, 1993; Tyson, 1993). 135 University of Ghana http://ugspace.ug.edu.gh Cuticles which are part of the translucent phytoclasts depicts the outermost waxy covering of the single layer of epidermal cells of leaves, stems of most plants (Batten, 1996). Preservation of cuticles occurs in fluvio-deltaic, lacustrine and low energy environments (Tyson, 1987, 1995) and their abundances in the sediments reduces away from the delta distributaries (Gastaldo and Huc, 1992). Cuticles have been generally documented in high percentages from low energy, onshore fluvio-deltaic and lacustrine palaeoenvironments (e.g. Batten, 1973; Nagy et al., 1984; Smyth et al., 1992). Cuticle debris is most buoyant variety of organic matter of the structured terrestrial organic matter and results from the settling of the flotation and suspension loads under low energy conditions (Fisher, 1980). Opaque phytoclast (Black debris): Black (opaque) wood concentrations in antique sediments have additionally been discovered to be of extraordinary palaeoenvironmental significance, and they have been found to reflect deposition polarity (onshore-offshore location), distance of sediment transport, and oxygenation level of host sediments (Deaf, 2009). The process of decay and the accompanying loss of weight are most fast when wood is exposed to the atmosphere. The opaque phytoclast is normally expressed to be a result of terrestrial post-depositional alteration, depicting variations in the water column permitting exposure to sub-aerial oxidation and oxidation during transport (Tyson, 1993, 1995; Mendonça Filho et al.,2012). According to Batten (1996) wood gets degraded to ‘black debris’ by exposure to oxygenated conditions by microbial and fungal action. Black wood fragments in high percentages have been archived from ancient high energy, proximal, coarse grained sediments of fluvial and delta-top systems (Fisher, 1980; Nagy et al., 1984; Smyth et al., 1992). The particle size of black wood has been documented to generally reduce in offshore direction (e.g. Habib, 1982; Gorin and Monteil, 1990). Black wood offshore particle size reduction was attributed to the fragmentation of large black wood particles during the long-distance transport with associated reduction in concentration of black wood (Tyson, 1995). 136 University of Ghana http://ugspace.ug.edu.gh Membranes: Mendonça Filho et al. (2012) intimated that, membranes are pale grey particles, thin, commonly transparent, with form of sheets and clear outlines, showing no visible cellular structures and depicts the cutine layer of the epidermis of leaves or branches from higher plants which can be strongly or weakly fluorescent. Membranous tissues are type of structured plant debris that are retrieved from the collenchyma and parenchyma of the non-epidermal, non- lignified tissues. These tissues are sensitive structures and are made of promptly degradable cellulosic material (Tyson, 1995). According to Tyson (1995) concentrations of the tissues are high in non-marine and proximal deltaic facies and tend to be rare in offshore direction. In prevailing oxic conditions they tend to degenerate three times quicker than more durable lignified woods (e.g. Stout et al., 1981). 5.1.3.2 Palynomorphs The palynomorphs refers to all discrete acid resistant, organic walled microfossils. The term palynomorph was proposed by Tchudy (1961) to allude to all discrete HCl and HF-resistant, organic-walled (unicellular, multicellular, or colonial) microfossil that might be present in palynological preparations. They are discrete, coherent, individual or colonial entities and categorize into terrestrial (sporomorphs) and aquatic (marine and fresh water) subgroups (Tyson, 1995) (Table 5.3). 5.1.3.2.1. Marine palynomorphs: This includes dinoflagellate cysts, acritarchs and prasinophytes. Dinoflagellate cysts are organic-walled, fossilized bodies that are produced by unicellular algae during the non-motile resting (sexual) phase of their life cycle and are made of generally resistant ‘dinosporin’ and are archived in the geologic record from the late Triassic to the present (Evitt, 1985). They are totally marine organisms and significant primary producers 137 University of Ghana http://ugspace.ug.edu.gh (Traverse, 2007). The cysts get fossilized and can be perceived by the plated surface, apical, and antapical horn and processes. According to Tyson (1993) the high concentrations of the dinoflagellate cysts occur in temperate to tropical shelf territories away from active fluvial- deltaic sources and in zones of the improved primary productivity. The proportion of dinocysts to sporomorphs (the marine influx index or marine: continental ratio) shows transgressive- regressive trends in ancient sediments (Habib, 1979; Lister and Batten, 1988; Prauss, 1989). High assorted variety and low dominance of dinoflagellate cysts happen in distal offshore marine shelf settings (Lister and Batten, 1988; Habib et al., 1992) and low assorted variety, high predominance assemblages demonstrate nearshore settings. High dinoflagellate cysts diversity likewise demonstrates high stands of global sea-level changes (Bujak and Williams, 1979; Goodman, 1987; Prasad et al., 2013). Lower numbers and/diversity have also been attributed with some dysoxic-anoxic palynofacies (Tyson, 1989; Batten and Marshall 1991; Batten, 1996). Acritarchs are hollow, organic-walled, eukaryotic unicellular of unknown biological affinities, which go from the mid-Precambrian to pre-Quaternary (Armstrong and Brasier, 2005) and are geographically widespread (Tyson, 1995). Their high relative abundances demonstrate shallow marginal marine settings of mainly brackish water in the in the Mesozoic ((Davey, 1970; Downie et al., 1971; Burger, 1980; Prauss, 1989; Deaf, 2009). Prasinophyte algae on the other hand are a group of non-cellulosic, green, flagellate algae, which have a geographical range from the Ordovician to Recent (Armstrong and Brasier, 2005). The presence of fossilized structures (phycomata) of prasinophyte algae have been discovered to be related with shelfal and oceanic settings with organic-rich sediments deposited in dysoxic-anoxic conditions (Tyson, 1984, 1989). Fossil prasinophyceae are rarely related with fresh water, unlike some modern taxa (Tappan, 1980). Their presence in the basin margin 138 University of Ghana http://ugspace.ug.edu.gh successions is primarily taken to suggest marine or brackish-marine conditions, or short-lived marine incursions (Guy-Ohlson and Norling, 1988; Lister and Batten, 1988; Batten, 1996). 5.1.3.2.2. Freshwater microplankton Freshwater and marine algae parts can both be found in palaeopalynological slides with assortment in shapes and sizes relying upon genus and species. They retain their colonial structure, have a lustrous colour and show up clearly under UV fluorescent light (Tyson, 1995; Traverse, 2007). Fresh water forms include chlorococcalean algae, for example, Pediastrum and Botryococcus alga. The presence of fossil colonies of Botryococccus alga occur with amorphous organic matter and proposes accumulation in dysoxic-anoxic conditions (Batten, 1996). The presence of Botryococcus and/or Pediastrum in the sedimentary record is associated with the formation of high-quality oil source rocks (Cane, 1976; Hutton, 1988). Fresh to brackish water conditions can be surmised from the presence of Botryococcus, as it has been recorded from antiquated lacustrine, fluvial, lagoonal, and deltaic/nearshore marine sediments (Piasecki, 1986; Riding et al., 1991; Williams, 1992). Pediastrum has additionally been found with high abundances in low salinity lakes and furthermore transported by fluvial systems into nearshore shelfal situations (Singh et al., 1981; Hutton, 1988). Other chlorococcalean algae include Scenedesmus and Tetraedron. 5.1.3.2.3. Zoomorph It is constituted by animal-derived palynomorphs including foraminiferal linings, chitinozoa and scolecodonts. It is recognizable as fragment zoomorph palynomorphs (Tyson, 1989 and 1995; Mendonça Filho et al., 2012). Microforaminiferal linings, a term formulated by Wilson and Hoffmeister (1952) applies to the acid resistant foraminiferal remains (less than 150 μm in size), found in the palynological 139 University of Ghana http://ugspace.ug.edu.gh preparations. The natural dissolution or breakage of calcareous microforaminiferal tests brings about liberation of their organic linings (Golubic and Schneider, 1979; Mc Neil, 1997) which keep up pretty much internal test morphology of the original foraminifers (Concheyro et al., 2014). The relative abundances of microforaminiferal test linings can be used to indicate depositional settings under normal marine conditions (Lister and Batten, 1988; Stancliffe, 1989). Batten (1982) showed that recurrence of microforaminiferal linings increments in marine facies are related with rich amorphous organic matter. The linings are generally recorded with dinoflagellate cysts in the sediments deposited along the coasts (Warrington, 1982; Davies, 1985; Kumaran and Rajshekhar, 1992; Singh et al., 2013). They have been effective occupants of each aquatic environment from deep oceans to brackish water lagoons, estuaries and scarcely in freshwater streams, lakes (Gandhi and Solai, 2010). Scolecodonts are elements of the jaw of benthic polychaete annelid forms which range from Ordovician to recent and they occur in marine settings (Tyson, 1995). Chitinozoa are an extinct group marine organic-walled, flask or bottle-shaped microfossils (50 μm to 2 mm in size) that occur in rocks of Ordovician to Devonian age. Chitinozoa have proved to be very useful in biostratigraphic dating of those Paleozoic fine-grained metasediments in which all the organic matter is opaque. They also have potential as thermal maturity indices; because with the progressive thermal alteration the test changes from translucent and amber colored to brown and finally black (opaque) (Tyson, 1995; Mendonça Filho et al., 2012). 5.1.3.2.4. Sporomorph (Terrestrial Palynomorphs): Spores and pollen-grains are the terrestrial constituent of the palynomorphs and are the result of the life-cycle of embryophytic plants (Traverse, 2007) which forms important components of the palynofacies. The embryophytes are plants that produce true embryos, the spore 140 University of Ghana http://ugspace.ug.edu.gh producing bryophytes and pteridophyte (fern type) and the pollen grains producing gymnosperms (e.g. conifers) and angiosperms (Traverse, 2007; Tyson, 1995; Mendonça Filho et al., 2012). Spores and pollen grains after their production gets dispersed by insects, wind and water. Their exines gets deposited in shallow water estuarine, lagoonal and lacustrine sediments and are useful in the interpretation of depositional environments and the reconstruction of the vegetational histories (Pocock et al., 1988). Their concentration is restricted to the vicinity of the active fluvio-deltaic sources (Mudie, 1982). The hydrodynamic equivalence of spores has been discovered to be constrained by spore sizes, where high proportions of ornamented, thick- walled, more dense spores have been found to concentrate in proximal high energy nearshore settings and reduce from the source land in contrast with smooth, thin-walled, less dense spores (e.g. Lund and Pedersen, 1985; Mutterlose and Harding, 1987; Tyson, 1989; Dybkjaer, 1991; Deaf, 2009). Pteridophyte spores are generally known to flourish in warm humid low lands (for example riversides and coastal areas: Pelzer et al., 1992; Abbink et al., 2004) and subsequently high abundances of pteridophyte spores (e.g. Deltoidspora, Concavissimisporites, and Impardecispora) have been recommended as a proxy for humid conditions (e.g. Abbink et al., 2004; Bornemann et al., 2005). Pollen grain can take many forms and the sphaeroidal grains forms such as the Araucariacites are considered as some of the most buoyant members of the sporomorph group (Deaf, 2009). The circumpolles Classopollis has been archived to increase in a basinward direction with respect to their relative abundances (e.g. Hughes and Moody-Stuart, 1967; Habib, 1979), furthermore, subsequently recommended as an indicator of relative proximity to fluvio-deltaic systems (Tyson, 1984; 1993; 1995). It is known as an important proxy indicator for 141 University of Ghana http://ugspace.ug.edu.gh palaeoclimatic conditions (Deaf, 2009). As indicated by Doyle et al. (1982), lower abundances of the angiosperm pollen Afropollis of possible Winteraceaen affinity have been recorded from warm and dry intracontinental basins. The presence of fungal spores can indicate a close proximity to, or redeposition from, active fluvio-deltaic source areas (especially deltaic, estuarine, or lagoonal oxic facies) and their association with high abundance of dinoflagellate cysts and foraminiferal linings are indicative of upwelling areas (Tyson, 1995; Mendonça Filho et al., 2012). The sporomorph group absolute abundances have been found to decline exponentially in an offshore trend in ancient environments (e.g. Reyre, 1973; Habib, 1982). Furthermore, Tyson (1995) proposed that there is some relationship between high abundances of miospores regularly found in fluvio-deltaic systems with the sand and silt lithologies normally found in such systems. 5.2 PALYNOFACIES ASSOCIATIONS AND PALAEOENVIRONMENTAL INTERPRETATIONS. According to Tyson (1995), the choice of palynofacies parameters ultimately depends upon the objectives of the investigation and the classifications of the kerogen and palynomorphs used in data collection. This study adopts the classification scheme of Tyson (1993, 1995) for palynofacies analysis. Generally, palynofacies studies are utilized for depositional and paleoenvironmental reconstruction and kerogen analysis (Tucker, 1988; Gorin and Steffen, 1991; Tyson, 1995; Jaramillo and Oboh-Ikuenobe, 1999; Batten et al., 2005). 142 University of Ghana http://ugspace.ug.edu.gh Table 5.4: Major subdivisions of the Palynomorph Group (After Tyson, 1995). Natural categories Sub-categories often used in palynofacies studies Sporomorph subgroup Pteridophyte isospores Smooth & thin-walled vs. thick and strongly Microspores (<200µm) ornamented spores Saccate spores Pteridophyte megaspores (>200µm) Gymnosperm pollen and prepollent Bissacate pollen Simple, small, sphaeromorph pollen Angiosperm pollen Fungal spores Fungal sclerotia Phytoplankton subgroup (including meroplankton) Dinoflagellates cysts (dinocysts) Peridiniales (Taylor) Peridinoid cysts Gonyaulacales (Taylor) Gonyaulacoid cysts Proximate and proximochorate morphotypes Chorate morphotypes Holocavate and circumcavate morphotypes Prasinophyte phycomata Tasmanitids Crassosphaerids Pterospermellids Cymatiosphaerids (‘herkomorphs’) Acritarchs Acanthomorphitae Forms with short processes Forms with long processes Polygonomorphitae Netromorphitae Cyanobacteria Chroococcales (e.g. Gloeocapsomorpha) Rivulariaceae (e.g. Celyphus) Oscillatoriales Chlorococcale colonial algae Botryococcaceae (Botryococcus) Hydrodictyaceae (Pediastrum) Rhodophyte spores (‘circular bodies’) Zoomorph subgroup Foraminiferal test-linings Scolecodonts Chitinozoa 143 University of Ghana http://ugspace.ug.edu.gh The amorphous organic matter (AOM)-Palynomorphs-Phytoclasts (APP) ternary kerogen plot of Tyson (1995) is used to characterize kerogen assemblages to identify the environment of deposition and kerogen types (Figure 5.1 and Table 5.5). Palynological and palynofacies data plot on the APP ternary diagram of Tyson (1993) also enabled the discrimination of the respective samples into clusters which refer to the palynofacies associations. Binary or ternary diagrams are regularly used to characterize the typical signatures of optical assemblages from the relative proportions of significant organic constituents. According to Tyson (1995) the main advantage of ternary diagrams is that they give a spatial separation that is useful for grouping samples into empirically defined associations or assemblages. As stated in Mendonça Filho et al. (2012), one of the more complete diagrams utilized in palynofacies investigation is the APP diagram because it correlates the percentage of the three main groups of kerogens identified in transmitted white light. Apart from the APP diagram, there are various diagrams used to represent palynofacies data and utilized to interpret its results which is dependent on the objectives of the study and data collected. The Microplankton-Spore-Pollen (MSP) ternary diagram was utilized by Federova (1977) and Duringer and Doubinger (1985) to indicate general depositional environments and associated regressive-transgressive trends (e.g. Traverse, 1988; Tyson, 1993, 1995). Palynomorphs themselves have environmental significance because they occur in terrestrial and marine environments and can infer palaeoclimatic and palaeoenvironmental characteristics (e.g. Tyson 1995). Terrestrial palynomorphs (sporomorphs) are mainly used as substantial indicators of the conspicuous allochthonous fluviatile input as well as proximity to shoreline trends within the depositional palaeoenvironment (Tyson, 1995; Pittet and Gorin, 1997; Tahoun et al., 2017; Mansour et al., 2018). In this study the APP kerogen plot of Tyson (1995) 144 University of Ghana http://ugspace.ug.edu.gh is used to interpret paleoenvironmental conditions (Fig 5.1) and Table 5.5 representing palynofacies definitions on APP ternary with kerogen type and generation potential (after Tyson, 1993, 1995). Redox plus masking effect Figure 5.1: AOM-Palynomorphs-Phytoclasts (APP) ternary plot showing environment of deposition and kerogen types (after Tyson, 1993). 145 University of Ghana http://ugspace.ug.edu.gh Table 5.5: Palynofacies defined on the triangle -APP with kerogen type and generation potential (after Tyson, 1993, 1995). Field Environment Comments Spores Microplankton Kerogen Type Highly High phytoclast supply dilutes all other Usually high Very low III, gas prone I proximal shelf components or basin Marginal AOM diluted by high phytoclast input, High Very low III, gas prone II dysoxic-anoxic but AOM preservation moderate to basin good. Amount of marine TOC dependent on basin redox state and dilution Heterolithic Generally low AOM preservation. High Common to III or IV, gas III oxic shelf Absolute phytoclast abundance abundant prone (proximal dependent on actual proximity to Dinocysts shelf) fluvio-deltaic source. Oxidation and dominant reworking common. Shelf to basin Passage from shelf to basin in time (e.g. Moderate to Very low-low III or II, IV transition Increased subsidence, water depth) or high mainly gas space (e.g. Basin slope). Absolute prone phytoclast abundance depends on proximity to source and degree of redeposition. Amount of marine TOC depends on basin redox state. Iva dysoxic-suboxic, Ivb suboxic-anoxic. Mud-dominated Low to moderate AOM (usually Usually low Common to III>IV, gas V oxic shelf degraded) palynomorphs abundant. abundant prone (distal shelf) Light coloured bioturbated. Dinocysts calcareous mudstones are typical dominant Proximal High AOM preservation due to Variable low to Low to common. II, oil prone VI suboxic-anoxic reducing basin conditions. Absolute moderate Dinocysts shelf phytoclast content may be moderate to dominant high due to turbidite input and /or general proximity to source. Distal dysoxic- Moderate to good AOM preservation. Low Moderate to II, oil prone VII anoxic shelf Low to moderate palynomorphs. Dark common. coloured slightly bioturbated mudstones Dinocysts are typical. dominant Distal dysoxic- AOM –dominated assemblages. Low Low to moderate. II>I, oil VIII oxic shelf Excellent AOM preservation. Low to Dinocysts prone moderate palynomorphs (partly due to dominant, % masking). Typical of organic-rich prasinophytes shales deposited under stratified shelf increasing sea conditions. IX Distal suboxic- AOM-dominated assemblages. Low Low Generally low II>I, highly anoxic shelf/ abundance of palynomorphs partly due prasinophytes oil prone basin to masking. Frequently alginitic rich. often dominant Deep basin or stratified shelf sea deposits, especially sediments starved basins. 146 University of Ghana http://ugspace.ug.edu.gh 5.2.1 Lynx-1X well Seven (7) palynofacies associations (PF-1 to PF-7) have been identified in the Lynx-1X well between the interval 5300 m – 2520 m based on the quantitative analysis from microscopic observations of proportions of the particulate organic matter (POM) groups represented in Table 5.6 and Figure 5.21. Table 5.6: Percentage composition of palynofacies associations of particulate organic matter (POM) in Lynx-1X well. Palynofacies associations AOM Opaque Translucent Palynomorphs phytoclasts Phytoclasts PF-1 14 81 4 1 PF-2 45 44 9 2 PF-3 71 23 5 1 PF-4 68 15 16 1 PF-5 58 10 6 26 PF-6 30 18 25 27 PF-7 28 28 5 39 5.2.1.1 Palynofacies type 1 (PF-1) (Opaque phytoclasts) dominant with moderate AOM) (Fig 5.2a). This palynofacies associations is identified between sample depths intervals (5295 m – 5300 m) - (5035 m – 5040 m), (4715 m – 4720 m) -(4655 m – 4660 m), 4540 m - (4055 m – 4060 m) and (3975 m – 3980 m) - (3955 m – 3960 m). It is dominated by opaques (up to 81% of total POM) with AOM, translucent phytoclasts and palynomorphs (mainly sporomorphs) contributing 14%, 4% and 1% respectively (Fig. 5.b). Marine palynomorphs are absent. Common among recovered sporomorphs include Classopollis spp, Ephedripites spp. with associated taxa of Afropollis spp, Elaterosporites spp., Retimonocolpites, Araucariacites and Cyathidites. Palaeoenvironmental interpretation: PF-1 displays dominance of opaque phytoclasts which are dark brown to black in color and composed of moderately well-preserved equant to lath- 147 University of Ghana http://ugspace.ug.edu.gh shaped fragments of different sizes. Some of the opaque particles have pitted structure showing that they are derived from tracheid tissues. The samples in PF-1 plotted in field II of Tyson’s APP ternary diagram which suggests a redox condition of deposition in a marginal dysoxic- anoxic basin (Fig. 5.3). PF-1 recorded low to none occurrence of spores and might be attributed to the oxidation of some of the palynomorphs to be recovered as opaques. The very high percentage of opaque phytoclasts are the result of oxidation conditions, and either proximity to terrestrial sources or redeposition of terrestrial organic matter from fluvio-deltaic environment (Tyson 1989, 1993; Kholeif and Ibrahim, 2010; Carvalho et al., 2013). Zobaa et al. (2013) infers that, deposition of sediments might have occurred close to fluvial sources where some of the phytoclasts were oxidized to opaques during transportation. Chiaghanam et al. (2013) further suggested the dominance of opaque phytoclasts to indicate fluvio-deltaic/nearshore environment. A marginal dysoxic-anoxic basin condition in a fluvio-deltaic/nearshore environment is suggested for PF-1. Kerogen Type: This palynofacies association is identified as kerogen type III-IV (gas prone) based on the dominance of opaque phytoclasts with low to none palynomorphs dominated by sporomorphs. 148 University of Ghana http://ugspace.ug.edu.gh (b) Figure 5.2: (a) Representative photograph of palynofacies association PF-1, sample depth 3600m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, OP = Opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-1 from the Lynx-1X well. 149 University of Ghana http://ugspace.ug.edu.gh Figure 5.3: APP Ternary diagram for PF-1 samples from Lynx-1X well (after Tyson, 1993). 5.2.1.2 Palynofacies type 2 (PF-2) (Equal abundance of AOM and Opaque phytoclasts) (Fig. 5.4a). PF-2 is recognized at sample depths between (4995 m – 5000 m) - (4735 m – 4740 m), (4635 m – 4640 m) - (4580 m) and (4035 m – 4040 m) - (3995 m – 4000 m). Opaque phytoclasts and AOM dominates the total organic matter composition of this palynofacies with relatively equal amount (up to 44% and 45% respectively) (Fig. 5.4b). Phytoclasts constitute 9% with palynomorphs (mainly sporomorphs) 2% of POM. Palaeoenvironmental interpretation: AOM present consists mainly of moderate to good preserved pale yellow to orange particles mostly showing diffused fragments with granular forms present in small amounts. The translucent phytoclasts are brown in colour and opaque phytoclasts are equant and lath-shaped. The palynomorphs recovered are usually orange to medium brown and their relative abundance same as PF-1 and composed of terrestrial taxa (mainly pollen grains). PF-2 plots in the field VI of the APP diagram of Tyson (1995) indicating 150 University of Ghana http://ugspace.ug.edu.gh deposition in a proximal suboxic-anoxic shelf environment (Fig. 5.5). Palynomorphs recovered are wholly sporomorphs dominated by pollen grains in small amounts. The abundance of opaques and AOM with low sporomorphs dominated by the pollen group indicates deposition in a proximal marginal marine/nearshore environment which is supported by Microplankton- Spore-Pollen (MSP) ternary plot (Fig. 5.6). The discussion above suggest PF-2 is deposited under a proximal suboxic-anoxic shelf conditions in a proximal marginal marine/nearshore environment. Kerogen Type: This palynofacies association is classified as kerogen type II/III (gas prone) based on moderately preserved pale yellow to orange AOM and the high diluting effect of the opaques. 151 University of Ghana http://ugspace.ug.edu.gh Figure 5.4: (a) Representative photograph of palynofacies association PF-2, sample depth 3600m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, OP = opaque phytoclast, TP = Translucent Phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-2 from the Lynx-1X well. 152 University of Ghana http://ugspace.ug.edu.gh Figure 5.5: APP Ternary diagram of studied samples from the Lynx-1X well (after Tyson, 1993). Figure 5.6: MSP Ternary plot for PF-2 samples from Lynx-1X well (After Federova, 1977; Duringer and Doubinger, 1985). 153 University of Ghana http://ugspace.ug.edu.gh 5.2.1.3 Palynofacies type 3 (PF-3) (AOM dominant with high opaques) (Fig. 5.7a) PF-3 occurs at sample depths between (3750 m – 3760 m) - (3656 m – 3660 m) and 3520 m – 3320 m. It is characterized by high percentage of AOM (71%) and common opaque phytoclasts (23%). PF-3 has relative abundance of translucent phytoclasts (5%) and palynomorphs (1%) of total POM (Fig. 4.7b). AOM is yellowish to orange in colour and well preserved. The palynomorphs are composed of terrestrial origin and dominated by pollen grains with occasional dinocyst (Fig. 5.21). Palaeoenvironmental interpretation: The dominance of AOM is suggested to be as a result of the combination of environments with high preservation rates and low energies in reducing basins with increased water column which result in a dysoxic-anoxic bottom conditions (Batten, 1983; Tyson, 1993, 1995; Ibrahim et al., 2002; Kholeif and Ibrahim, 2010). According to Tyson (1993) miospores being the least component of a palynofacies may suggest a shallower offshore setting as increase in miospores percentages were equated to proximity of depositional sites to active sources of terrestrial organic matter input. The plot of PF-3 samples on Tyson’s APP ternary diagram were constrained in field IX (Fig. 5.8), indicating deposition in a distal suboxic-anoxic basin condition. MSP diagram supports the marginal marine to shallow marine depositional settings (Fig. 5.9) which is inferred due to the presence of some dinoflagellates and the percentage of opaques. From the discussions above, it is suggested that deposition of the samples yielding palynofacies PF-3 took place in a marginal marine to shallow marine environment under distal suboxic-anoxic conditions. Kerogen Type: The kerogen type represented by the palynofacies association is type II>I (highly oil prone) based on the dominance of well-preserved pale yellowish to orange AOM. 154 University of Ghana http://ugspace.ug.edu.gh Figure 5.7: (a) Representative photograph of palynofacies association PF-3, sample depth 3660m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, OP = Opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-3 from the Lynx-1X well. 155 University of Ghana http://ugspace.ug.edu.gh Figure 5.8: APP Ternary diagram for PF-3 samples from Lynx-1X well (after Tyson, 1993). Figure 5.9. MSP Ternary plot of studied samples from the Lynx-1X well (After Federova, 1977; Duringer and Doubinger, 1985). 156 University of Ghana http://ugspace.ug.edu.gh 5.2.1.4 Palynofacies type 4 (PF-4) (AOM dominant with relatively equal abundance of opaques and phytoclasts (Fig. 5.10a) This palynofacies type is recorded at samples depth intervals from 3640 m – 3540 m. The facies are dominated by AOM (68% of total POM) with relatively equal amounts of opaques (15%) and phytoclasts (16%) (Fig. 4.10b). AOM is mainly well-preserved pale yellow to orange particles and similar to PF-3. The translucent phytoclasts are moderate to well preserved and brown in colour with opaque phytoclasts having dark brown to black in colour. Palynomorphs (mainly of terrestrial origin) make up 1% of POM and consist mainly of pollen grains. Palaeoenvironmental interpretation: Amorphous organic matter preservation is primarily controlled by oxygen content and there exists a relationship between its colour and depositional environment (Valdes et al., 2004). PF-4 samples were constrained in field IX of Tyson’s APP ternary diagram indicating deposition in a distal suboxic-anoxic basin condition (Fig. 5.11) in a shallow marine environment due to the dominance of AOM and absolute diluting effects of phytoclasts. According to Tyson (1995), this field of AOM dominated assemblages with low occurrence of palynomorphs is partly due to masking. Based on the above discussion, PF-4 is suggested to be deposited under a distal suboxic-anoxic basin condition in a shallow marine environment. Kerogen Type: The field is characterized as kerogen type II>I (highly oil prone) based on the dominance of AOM. 157 University of Ghana http://ugspace.ug.edu.gh Figure 5.10: (a) Representative photograph of palynofacies association PF-4, sample depth 3600m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, OP = opaque phytoclast, TP = translucent phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-4 from the Lynx-1X well. 158 University of Ghana http://ugspace.ug.edu.gh Figure 5.11. APP Ternary diagram for PF-4 samples from Lynx-1X well (after Tyson, 1993). 5.2.1.5 Palynofacies type 5 (PF-5) (AOM dominant with palynomorphs) (Fig. 5.12a) PF-5 occurs at sample depths interval from 3300 m – 2900 m. It is dominated by moderate to good preservation of AOM (58%) and palynomorphs (26%) of total POM of which marine palynomorphs (dinocysts) constitutes 75% while the sporomorphs forms the remaining 25% of total palynomorphs. PF-5 has relative abundance of opaque phytoclasts (10%) and phytoclasts (6%) of total POM (Fig 5.12b). Palaeoenvironmental interpretation: AOM present are mostly pale yellow to orange particles. The opaques (black debris) are dark brown to black in colour exhibiting varied sizes. The plot of samples on the APP ternary diagram are constrained in field VIII (Fig. 5.13), indicating deposition in a distal dysoxic-oxic shelf conditions. The gonyaulacoid cysts mainly of chorate forms dominate (70% of total marine palynomorphs) over the peridinoid cysts within this interval represented by the Gonyaulacoids/Peridinoids (G/P) plot (Fig. 5.20) with very high G/P ratio. 159 University of Ghana http://ugspace.ug.edu.gh Marine components dominate over terrestrial which indicates deposition far away from the shoreline (Williams et al., 2018). The most common marine palynomorphs genera are Spiniferites, Trichodinium, Adnatosphaeridium, Oligosphaeridium, Cordosphaeridium, Andalusiella, Palaeocystodinium and Cerodinium and among the sporomorphs are Cyathidites, Cicatricosisporites, Proxapertites and Longapertites. Work done by Davey (1970), Habib (1983), Tyson (1984), Balch et al. (1983) and De Vernal & Giroux (1991) on fossil dinoflagellate cysts and modern dinoflagellates suggested that dinoflagellate cysts tend to increase in Gonyaulacoids/Peridinoids (G/P) ratio in an oceanward direction until they reach the continental slope, after which dinoflagellate start to show a reduction in species abundances and diversity. However, the presence of Spiniferites, Exochosphaeridium and Florentinia in this palynofacies association is commonly related to open marine, outer shelf settings, with Spiniferites recorded in high numbers in these intervals (Marshall and Batten, 1988; Brinkhuis, 1994). The dominance of the chorate dinocysts over the cavate and proximate cysts recorded from all samples within this palynofacies type generally indicate development of strong marine transgression and deposition in an open marine environment (Tyson, 1993; Williams, 1992; Riding and Hubbard, 1999). The increase in frequencies of Oligosphaeridium and Florentinia in PF-5 are well documented to be representative for the open marine (middle shelf) conditions (Wall et al., 1977; Dale, 1983; Lister and Batten, 1988). The increase in frequencies of peridinoids at levels from 3100 – 2900 m of PF-5 suggests deposition moving from deeper open marine settings (outer neritic) from 3300 – 3120 m into a shallower open marine setting (middle neritic) from 3100 – 2900 m (Fig. 5.20). Open marine gonyaulacoid cysts which dominates recovered dinoflagellate cysts from supports the offshore depositional environment of this palynofacies type (Downie et al., 1971; Islam, 1984) and 160 University of Ghana http://ugspace.ug.edu.gh supported by the MSP ternary plot (Fig. 5.14). Low concentrations of phytoclasts recovered in PF-5 supports the suggested offshore setting, where irrelatively low concentrations were equated to weak terrestrial influx and deposition in distal settings located far from land vegetation (Muller, 1959; Pocklington and Leonard, 1979; Tyson, 1993). The strong increment of palynomorphs especially the marine taxa with low occurrence of sporomorphs recorded in this palynofacies association leads to a deduction that ties in with the general suggestion of a more offshore marine setting, as sporomorphs absolute abundances recorded from sediments of ancient environments are found to decrease exponentially in an offshore trend (e.g. Reyre, 1973; Habib, 1983; Habib and Drugg, 1987; Deaf 2009). Low to zero occurrence of pteridophytes (e.g. Cyathidites and Deltoidspora) in the studied intervals suggests a deposition far from those riverside and coastal areas (Kedves, 1986; Schrank and Mahmoud, 1998) and compliment the more offshore depositional setting of PF-5. Kerogen Type: PF-5 is classified as kerogen type II>I (oil prone) based on the dominance of AOM and marine dinocysts. 161 University of Ghana http://ugspace.ug.edu.gh OP (b) Figure 5.12: (a) Representative photograph of palynofacies association PF-5, sample depth 3060m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, DC = dinoflagellate cysts, OP= opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-5 from the Lynx-1X well. 162 University of Ghana http://ugspace.ug.edu.gh Figure 5.13: APP Ternary diagram for PF-5 from Lynx-1X well (after Tyson, 1993). Figure 5.14: MSP Ternary plot for PF-5 samples from Lynx-1X well (After Federova, 1977; Duringer and Doubinger, 1985). 163 University of Ghana http://ugspace.ug.edu.gh 5.2.1.6 Palynofacies type 6 (PF-6) (AOM, phytoclasts and palynomorphs abundant) (Fig. 5.15a). PF-6 is recognized in sample depths from 2880 m – 2720 m. This interval recorded 30% of AOM of the total organic matter composition with palynomorphs and phytoclasts constituting 27% and 25% respectively (Fig. 5.15b). Opaque phytoclasts contribute 18% of the total POM. Marine palynomorphs dominates the palynomorph assemblage (Fig. 5.21). Palaeoenvironmental interpretation: AOM present consists mainly of well-preserved pale yellow to orange particles. The translucent phytoclasts consist mainly of pale brown, moderate to well preserved structured plant fragments. Dinoflagellate cysts dominates the assemblage and contributes 72% of total palynomorphs (Fig. 5.20). The peridinoid cysts dominates (67% of total dinocysts) over the gonyaulacoid cysts (33% of total dinocysts) in depth intervals (2800m-2720m) with low G/P ratio while the gonyaulacoid cysts dominates (65% of dinocysts) over the peridinoids from 2880m-2820m with high G/P ratio (Fig. 5.20). Sporomorphs contribute (av. 28%) and dominated by pollen grains similar to those in PF-5. PF-6 plots in the field Iva and IVb of the Tyson APP diagram indicating deposition in a shelf to basin transition (IVa=dysoxic; IVb= suboxic-anoxic) conditions (Fig. 5.16). The recovered marine palynomorphs species in this palynofacies type is similar to PF-5 with dominance of peridinoids genus such as Cerodinium, Andalusiella, Dinogymnium, Palaeocystodinium, etc. from interval 2800m-2720m which are typical of shallow marine environment. Dam et al. (1998) inferred the predominance of peridinoid dinocysts cited above to reflect a period of transgression and therefore an increase in sea-surface temperature. Open marine gonyaulacoids similar to those discussed in PF-5 (e.g. Oligosphaeridium complex, Florentina mantellii, Spiniferites ramosus, Spiniferites cornutus, Spiniferites sp., Areoligera) dominates the interval 2880m-2820m. The sporomorphs components is similar to those discussed in PF-5 and indicates terrestrial influence on the depositional environment. The reduction in AOM 164 University of Ghana http://ugspace.ug.edu.gh frequencies in this association compared to PF-5 and increase in relative abundance of peridinoid cysts from 2800m-2720m reflects a proximal offshore setting. PF-6 above indicate a deposition in a shelf to basin transition condition in an offshore, most likely from an inner- neritic to middle-neritic environments. Kerogen Type: PF-6 is constituted by kerogen type III and II (oil prone) based on the abundance of AOM, palynomorphs (dominated by marine dinocysts) and phytoclast. 165 University of Ghana http://ugspace.ug.edu.gh Figure 5.15: (a) Representative photograph of palynofacies association PF-6, sample depth 3060m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, SP = sporomorph, DC = dinoflagellate cysts, OP = opaque phytoclast, TP = translucent phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-6 from the Lynx-1X well. 166 University of Ghana http://ugspace.ug.edu.gh Figure 5.16: APP Ternary diagram for PF-6 samples from Lynx-1X well (After Tyson, 1993). 5.2.1.7 Palynofacies type 7 (PF-7) (Palynomorphs with equal abundance of AOM and opaques) (Fig. 5.17a). PF-7 occurs between sample depths from 2700 m – 2520 m (Fig. 5.21). It is made up of equal relative abundance of AOM (28%) and opaque phytoclasts (28%) with abundant palynomorphs (39%) (Fig. 5.17b). Phytoclasts make up 5% of total POM. Most palynomorphs are yellowish orange to light brown in colour. The palynomorphs of marine origin (dinocysts) dominates the assemblage and contribute 80% of total palynomorphs with the sporomorphs making up 20% and dominated by pollen grains with associated pteridophyte spores. The dinocysts are dominated by gonyaulacoids which contributes 86% of the dinocysts with some common species in PF-6. Peridinoid cysts contributes the remaining 14% of dinocysts. 167 University of Ghana http://ugspace.ug.edu.gh Palaeoenvironmental interpretation: On Tyson’s APP ternary diagram PF-7 plots in field V which reflects distal mud-dominated oxic shelf conditions (Fig. 5.18). Common among the gonyaulacoid cyst genera are chorate forms (Spiniferites, Operculodinium, Lingulodinium, Adnatosphaeridium, Damassadinium, Glaphyrocysta, Diphyes and associated with minor amounts of Homotryblium, Achomosphaera, Turbiosphaera, Polysphaeridium, Oligosphaeridium, Cordosphaeridium, Areoligera, Fibrocysta, Hystrichokolpoma, Coronifera and Fibrocysta. Common among the peridinoid cyst genera are the cavate and proximate forms (Ifecysta, Apectodinium, Palaeocystodinium, Cerodinium and associated with minor amounts of Andalusiella and Cribroperidinium). The dominance of the gonyaulacoid cysts (Fig. 5.20) in this palynofacies association suggests an offshore environment of deposition (outer neritic) and supported by SPM plot which plotted in the offshore region of the ternary diagram (5.19). Occurrence of phytoclasts and opaques in moderate equal amounts supports the suggested offshore setting and discussed earlier in PF-6. PF-7, therefore, support an outer neritic environment under distal mud-dominated oxic shelf conditions. Kerogen Type: PF-7 is characterized by kerogen type II/III (gas prone) based on moderate AOM and opaques phytoclasts with abundant marine palynomorphs (Tyson, 1993, 1995). 168 University of Ghana http://ugspace.ug.edu.gh Figure 5.17: (a) Representative photograph of palynofacies association PF-7, sample depth 2560m from the Lynx-1X well. Key to labels: AOM = amorphous organic matter, SP = sporomorph, DC = dinoflagellate cysts, OP = opaque phytoclast, TP = translucent phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PF-7 from the Lynx-1X well. 169 University of Ghana http://ugspace.ug.edu.gh Figure 5.18: APP Ternary diagram for PF-7 samples from Lynx-1X well (after Tyson, 1993). Figure 5.19: MSP Ternary plot for PF-7 samples from Lynx-1X well (After Federova, 1977; Duringer and Doubinger, 1985). 170 University of Ghana http://ugspace.ug.edu.gh Figure 5.20: Relative percentage composition of Gonyaulacoids and Peridinoids in Lynx-1X well. 171 University of Ghana http://ugspace.ug.edu.gh Figure 5.21: Palynofacies assemblages showing POM (%) from Lynx-1X well. 172 University of Ghana http://ugspace.ug.edu.gh 5.2.2 Dzata-1 well Five palynofacies associations has been recognized between the interval 4390 m - 2450 m dependent on the proportions of the particulate organic matter (POM) groups. These associations are Palynofacies type 1(PT-1), Palynofacies type 2 (PT-2), Palynofacies type 3 (PT-3), Palynofacies type 4 (PT-4) and Palynofacies type 5 (PT-5) (Table 5.7, Fig. 5.38). 5.2.2.1 Palynofacies type 1 (PT-1) (AOM dominant with abundant Opaque phytoclasts) (Fig. 5.22a) PT-1 is identified between depth interval from 4390 – 4030 m. It is dominated by AOM and abundant opaque phytoclasts making up of 52% and 33% of total POM respectively (Fig. 5.22b). Palynomorphs (mainly of terrestrial origin) 7% and translucent phytoclasts making up 8% of POM. AOM preservation is moderate and pale yellow in colour. The opaque phytoclasts are dark brown to black whilst the translucent phytoclasts are yellowish brown in colour. The palynomorphs are mainly light orange to medium brown. Table 5.7: Percentage composition of palynofacies associations of particulate organic matter (POM) in Dzata-1 well. Palynofacies associations AOM Opaque Translucent Palynomorphs phytoclasts Phytoclasts PT-1 52 33 8 7 PT-2 24 28 27 21 PT-3 7 88 2 3 PT-4 72 4 6 18 PT-5 33 46 13 8 173 University of Ghana http://ugspace.ug.edu.gh Palaeoenvironmental interpretation: PT-1 were constrained in field VI of Tyson’s APP ternary diagram indicating deposition in a proximal suboxic-anoxic shelf condition (Fig. 5.23). The dominant sphaeroidal pollen grains (av. 90% of sporomorphs) (e.g. Araucariacites, Classopollis, Inaperturopollenites) over pteridophyte spores (Cyathidites, Deltoidspora) in PT-1 suggests a proximal offshore setting due to the absence of marine elements and abundant opaque phytoclasts. The sporomorph group is indicative of deposition in a more nearshore environment and supported by SPM plot (Fig. 5.24). Other associated pollen grains include Afropollis and Ephedripites which indicates an arid to semi-arid warm climatic conditions (e.g. Mahmoud and Moawad, 2002) and commonly inhabit in palaeotropical humid coastal plains (Schrank, 2001; El Beialy et al., 2011). Recovered foraminiferal linings at depth intervals (4370 m – 4230 m) indicates a form of marine influence on these facies. Based on the discussions, the AOM is diluted by phytoclasts input which is generally the opaque type and sporomorphs constituents in PT-1, it suggests a deposition in a nearshore environment under proximal suboxic-anoxic conditions. Kerogen Type: PT-1 is characterized by kerogen type II and III (oil prone) based on dominant AOM and abundant opaque phytoclasts. 174 University of Ghana http://ugspace.ug.edu.gh Figure 5.22: (a) Representative photograph of palynofacies association PT-1, sample depth 4370m from the Dzata-1 well. Key to labels: AOM = amorphous organic matter, OP= opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-1 from Dzata-1 well. 175 University of Ghana http://ugspace.ug.edu.gh Figure 5.23: APP Ternary diagram for PT-1 samples from Dzata-1 well (after Tyson, 1993). Figure 5.24: MSP Ternary plot for PT-1 samples from Dzata-1 well (After Federova, 1977; Duringer and Doubinger, 1985). 176 University of Ghana http://ugspace.ug.edu.gh 5.2.2.2 Palynofacies type 2 (PT-2) (Relatively equal abundance of opaques phytoclasts and phytoclasts (non-opaques) with AOM and palynomorphs) (Fig. 5.25a). This palynofacies assemblage covers the depths between 4010 – 3710 m and 3630 – 3230 m. It is characterized by the relative equal abundance of opaque phytoclasts (28%) and translucent phytoclasts (27%). AOM (24%) and palynomorphs (21%) of total POM (Fig. 5.25b). Palynomorphs of terrestrial origin (mainly sphaeroidal pollen grains) dominates (98% of total palynomorphs) this palynofacies association (Fig. 5.38). Sporomorphs recovered from this palynofacies type include Classopollis spp, Ephedripites spp., Elaterosporites spp. with associated taxa of Afropollis, Retimonocolpites, Araucariacites and Cyathidites. Palaeoenvironmental interpretation: The plot of samples on Tyson’s APP ternary diagram were constrained in field Iva indicating deposition in a dysoxic-suboxic conditions (Fig. 5.26). Most pteridophytic spore associations (e.g. Cyathidites, Deltoidspora) are low to zero in count for most of the intervals. The high amount of miospores (dominated by sphaeroidal pollen grains) occurrence and high relatively equal abundance of opaques and translucent phytoclasts would support a nearshore environment and supported by SPM plot (Fig 5.27). The decrease in the amount of AOM which has been found in shallow shelf sediments (e.g. Dow and Pearson, 1975; Bujak et al., 1977) can be attributed to the dilution by phytoclasts which is influenced by run-off from and proximity to adjacent landmass thereby suggesting a shallow marine influence. Based on the discussions above, PT-2 indicates a deposition in a dysoxic-suboxic conditions in a nearshore environment. Kerogen Type: It is constituted by kerogen type III (gas prone) based on the relative equal abundance of phytoclasts (opaques and translucent) and palynomorphs dominated by sporomorphs. 177 University of Ghana http://ugspace.ug.edu.gh Figure 5.25: (a) Representative photograph of palynofacies association PT-2, sample depth 3610m from the Dzata-1 well. Key to labels: AOM = amorphous organic matter, SP = sporomorph, OP = opaque phytoclast, TP = translucent phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-2 from Dzata-1 well. 178 University of Ghana http://ugspace.ug.edu.gh Figure 5.26: APP Ternary diagram for PT-2 samples from Dzata-1 well (after Tyson, 1993). Figure 5.27: MSP Ternary plot for PT-2 samples from Dzata-1 well (After Federova, 1977; Duringer and Doubinger, 1985). 179 University of Ghana http://ugspace.ug.edu.gh 5.2.2.3 Palynofacies type 3 (PT-3) (Opaques dominant) (Fig. 5.28a). PT-3 is located between depth interval from 3690 m – 3650 m in the Dzata-1 well. The dominant element within this palynofacies association is opaque phytoclasts (up to 88% of POM). It contains AOM, palynomorphs and translucent phytoclasts with relative abundance of 7%, 3% and 2% respectively (Fig. 5.28b). Palynomorphs recovery is dominated by (99-100%) terrestrial palynomorphs. The sporomorphs (dominated by sphaeroidal pollen grains) mainly Classopollis spp. with few Ephedripites and associated taxa of Retimonocolpites and Cyathidites. Palaeoenvironmental interpretation: The facies of PT-3 display dominance of opaque phytoclasts which are dark brown to black in colour. AOM, translucent phytoclasts and palynomorphs are medium to dark brown in colour. PT-3 plot in field II of Tysons APP ternary diagram indicating deposition in a marginal dysoxic-anoxic basin condition (Fig. 5.29). Chiaghanam et al. (2013) suggested the dominance of opaque phytoclasts to indicate fluvio- deltaic/nearshore environment. The dominance of opaque phytoclasts within this association are as a result of oxidation conditions, and either proximity to terrestrial sources or redeposition of terrestrial organic matter from fluvio-deltaic environment (Tyson 1993; Kholeif and Ibrahim, 2010; Carvalho et al., 2013). Zobaa et al. (2013) inferred that, the deposition of sediments with dominant opaques might have occurred close to fluvial sources where some of the phytoclasts were oxidized to opaques during transportation. Dominant opaques and palynomorphs dominated by sphaeroidal pollen grains supported by SPM ternary plot suggest a nearshore environment of deposition (Fig. 5.30). Based on the discussions, PT-3 must have been deposited in a marginal dysoxic-anoxic basin condition in a fluvio-deltaic/nearshore environment. Kerogen Type: PT-3 is identified as kerogen type III (gas prone) based on dominant opaque phytoclasts. 180 University of Ghana http://ugspace.ug.edu.gh Figure 5.28: (a) Representative photograph of palynofacies association PT-3, sample depth 3670m from the Dzata-1 well. Key to label: OP = opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-3 from Dzata-1 well. 181 University of Ghana http://ugspace.ug.edu.gh Figure 5.29: APP Ternary diagram for PT-3 samples from Dzata-1 well (after Tyson, 1993). Figure 5.30: MSP Ternary plot for PT-3 samples from Dzata-1 well (After Federova, 1977; Duringer and Doubinger, 1985). 182 University of Ghana http://ugspace.ug.edu.gh 5.2.2.4 Palynofacies type 4 (PT-4) (AOM dominant with palynomorphs) (Fig. 5.31a). This palynofacies occurs between sample depths 3210 m – 3170 m and 3010 m – 2450 m. The AOM dominates (72%) the total organic matter composition of this palynofacies (Fig. 5.31b). AOM is pale yellow to orange particles and of moderate to good in preservation state. Palynomorphs is 18% of total POM) with opaques and translucent phytoclasts forming 4% and 6% respectively of total POM. Palaeoenvironmental interpretation: PT-4 plotted in field VIII of Tyson’s APP ternary which indicate a deposition in a distal dysoxic-oxic shelf conditions (Fig. 5.32). AOM dominant with weak terrestrial influx (phytoclasts) indicates offshore settings for these facies. The sample interval 3210 m – 3170 m is primarily dominated by elements of terrestrial origin (97%) dominated by pollen grains (e.g. sphaeroidal forms) increased in offshore trends with recorded low amount of pteridophytes spores (e.g. Cyathidites and Deltoidspora). The interval 3010m-2450m is dominated by about 85% marine palynomorphs (of which 90% are chorate cysts group of gonyaulacoids). The most common gonyaulacoid cyst genera are Spiniferites, Cordosphaeridium, Glaphyrocysta, Trichodinium, Adnatosphaeridium, Florentinia and Oligosphaeridium. The most common peridinoid cyst genera are Andalusiella, Palaeocystodinium and Cerodinium. Most common among the sporomorphs are Araucariacites, Cyathidites, Proxapertites, Longapertites and associated with minor amounts Cicatricosisporites, Monosulcites, Tricolpites, Deltoidspora and Foveotriletes. The gonyaulacoid cysts (90% of total dinocysts) dominates over the peridinoid cysts (Fig. 5.34). Occurrence of common open marine gonyaulacoid chorate cysts such as Oligosphaeridium complex, Florentina mantellii, Spiniferites spp., Cordosphaeridium multispinosum etc. dominate dinoflagellate cysts from the interval (3010 – 2450 m) which supports the offshore depositional environment and supported by SPM diagram (Fig. 5.33). According to Muller, (1959), Pocklington and Leonard (1979), Tyson (1993), the low frequency occurrence of 183 University of Ghana http://ugspace.ug.edu.gh phytoclasts in PT-4 is equated to weak terrestrial influx and deposition in distal settings located far from land vegetation. The palynofacies association present from interval 3210 m – 3170 m suggests an inner-middle neritic environment while interval 3010 m – 2450 m is deposited in an outer neritic environment under distal dysoxic-oxic shelf conditions. Kerogen Type: PT-4 is classified as kerogen type II>I (oil prone) based on dominant AOM with palynomorphs. 184 University of Ghana http://ugspace.ug.edu.gh (b) Figure 5.31: (a) Representative photograph of palynofacies association PT-4, sample depth 2910m from the Dzata-1 well. Key to labels: AOM = amorphous organic matter, DC = dinoflagellate cysts. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-4 from the Dzata-1 well. 185 University of Ghana http://ugspace.ug.edu.gh Figure 5.32: APP Ternary diagram for PT-4 samples from Dzata-1 well (after Tyson, 1993). Figure 5.33: MSP Ternary plot for PT-4 samples from Dzata-1 well (After Federova, 1977; Duringer and Doubinger, 1985). 186 University of Ghana http://ugspace.ug.edu.gh Figure 5.34: Relative percentage composition of Gonyaulacoids and Peridinoids in Dzata-1 well. 5.2.2.5 Palynofacies type 5 (PT-5) (Abundant opaque phytoclasts and AOM) (Fig. 5.35a). This palynofacies is represented by sample depths interval from 3150 – 3030 m. The dominant element within this palynofacies association is opaque phytoclasts (46%) of total POM. AOM have relative abundance of 33%, translucent phytoclasts (13%) and palynomorphs (8%) (Fig. 5.35b). AOM present are generally moderately preserved and pale yellow to orange in colour. The opaque phytoclasts are dark-brown to black in colour and translucent phytoclasts are brown in colour. 187 University of Ghana http://ugspace.ug.edu.gh Palaeoenvironmental interpretation: This facies indicates a deposition under a marginal dysoxic-anoxic basin conditions as inferred from the ternary diagram of Tyson (1995), which plots in the palynofacies field II (Fig. 5.36). Palynomorphs recovered from these facies are mainly sporomorphs (dominated by sphaeroidal pollen grains) (Fig. 5.38). Dominant sphaeroidal gymnosperm pollen grains over pteridophyte spores suggests deposition of sediments must have taken place in settings that were far from fluvio-deltaic sources. The abundance of opaque phytoclasts together with moderate translucent phytoclasts would rather suggest a more nearshore environment which is further supported by MSP plot (Fig. 5.37). In PT-5, the phytoclasts (opaques and translucent) and AOM components associated with the palynomorph content suggests a nearshore environment, close to the terrestrial source area under marginal dysoxic-anoxic basin conditions. Kerogen Type: It is characterized by kerogen type III (gas prone) based on the abundant opaque phytoclasts and AOM with translucent phytoclast. 188 University of Ghana http://ugspace.ug.edu.gh Figure 5.35: (a) Representative photograph of palynofacies association PT-5, sample depth 3110m at from the Dzata-1 well. Key to labels: AOM = amorphous organic matter, OP = opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-5 from Dzata-1 well. 189 University of Ghana http://ugspace.ug.edu.gh Figure 5.36: APP Ternary diagram for PT-5 samples from Dzata-1 well (after Tyson, 1993). Figure 5.37: MSP Ternary plot for PT-5 samples from Dzata-1 well (After Federova, 1977; Duringer and Doubinger, 1985). 190 Univ ersity of Ghana http://ugspace.ug.edu.gh Relative abundance (%) Depth/m Palynofacies 20 40 60 80 associations PT-4 PT-5 PT-4 PT-2 PT-3 PT-2 PT-1 Figure 5.38: Palynofacies associations showing POM (%) from Dzata-1 well. 191 University of Ghana http://ugspace.ug.edu.gh 5.2.3 Dzata-2A Six palynofacies associations based on the proportions of the particulate organic matter (POM), were identified between 4426 – 2420 m in the Dzata-2A well with their relative abundance in percentages tabulated in table 4.8 and displayed in Figure 5.58. Table 5.8: Percentage composition of palynofacies associations of particulate organic matter (POM) in Dzata-2A well. Palynofacies associations AOM Opaque Translucent Palynomorphs Phytoclasts Phytoclasts PT-A 60 27 9 4 PT-B 33 18 24 25 PT-C 64 6 8 22 PT-D 37 32 23 8 PT-E 81 6 8 5 PT-F 57 8 17 18 5.2.3.1 Palynofacies type 1 (PT-A) (AOM dominant with abundant opaque phytoclasts) (5.39a). PT-A occurs between sample depths 4426 – 3930 m and 3630 – 3550 m. It is characterized by dominant AOM (60%) and high opaque phytoclasts (27%) of total POM (Fig. 5.39b; Fig. 5.58). AOM preservation is good. PT-A has relative abundance of translucent phytoclasts (9%) and palynomorphs (4%) of total POM. The opaque phytoclasts are dark-brown to black in colour, equant and lath-shaped of varied sizes. Translucent phytoclasts are brown in colour and orange to medium brown in palynomorphs. Palaeoenvironmental interpretation: The plot of samples on Tyson’s APP ternary diagram were constrained in field VI (Fig. 5.40), indicating deposition in a proximal suboxic-anoxic shelf condition. The palynomorphs are of terrestrial origin dominated by gymnosperm sphaeroidal pollen grains (e.g. Araucariacites, Classopollis, Inaperturopollenites) over pteridophyte spores (e.g. Deltoidspora, Cyathidites, Cicatricosisporites). The dominance of 192 University of Ghana http://ugspace.ug.edu.gh AOM is inferred to be as result of the combination of environments with high preservation rates and low energies in reducing basins with increased water column resulting in dysoxic or anoxic bottom condition (Batten 1983; Tyson 1993; Tyson 1995; Ibrahim et al., 2002; Kholeif and Ibrahim 2010). Sporomorphs are the least component of this facie which may suggest a shallower offshore setting as increase in sporomorphs percentages were equated to proximity of depositional sites to active sources of terrestrial organic matter input (Tyson, 1993). MSP diagram supports the nearshore to shallower offshore setting (Fig. 5.41). Based on the discussion above, Palynofacies type 1 (PT-A) indicates a deposition in a nearshore to shallow marine (inner neritic) environment under a proximal suboxic-anoxic shelf condition. Kerogen Type: These facies are characterized by kerogen type II/III (oil prone) based on the dominant AOM with high opaques. 193 University of Ghana http://ugspace.ug.edu.gh Figure 5.39: (a) Representative photograph of palynofacies association PT-A, sample depth 3990m from the Dzata-2A well. Key to labels: AOM = amorphous organic matter, SP = sporomorph, OP = opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-A from Dzata-2A well. 194 University of Ghana http://ugspace.ug.edu.gh Figure 5.40: APP Ternary diagram of studied samples from the Dzata-2A well (after Tyson, 1993). Figure 5.41: MSP Ternary plot for PT-A samples from Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 195 University of Ghana http://ugspace.ug.edu.gh 5.2.3.2 Palynofacies type 2 (PT-B) (Abundant AOM with relatively equal abundance of phytoclasts and palynomorphs) (Fig. 5.42a). PT-B is documented in sample depth intervals between 3810 – 3650 m. The elements of this palynofacies are constituted by AOM (33%), translucent phytoclasts (24%) and palynomorphs (25%) with relatively low occurrence of opaque phytoclasts (18%) of total POM (Fig. 5.42b). PT-B is primarily dominated by palynomorphs of terrestrial origin (95%) dominated by pollen grains (sphaeroidal forms) with marine dinoflagellates cysts constituting 5% and dominated by peridinoid cysts (80% of total dinocysts) (Fig. 5.58). Palynomorphs are generally orange and pale brownish in colour whilst the translucent phytoclasts mainly consist of pale brown with moderately preserved structured plant fragments. Palaeoenvironmental interpretation: PT-B plots in field IVa of Tyson’s APP ternary which indicates a deposition in a shelf to basin transition under a dysoxic-suboxic conditions (Fig. 5.43). High occurrence of xerophytes (e.g. Classopollis and Ephedripites) suggests a deposition in a semi-arid to arid climatic conditions of this facies. High percentages of the translucent phytoclasts indicates freshwater influx on this facie. Peridinoids cysts dominate over the gonyaulacoids (G/P) which indicates an inner neritic/nearshore depositional environment and supported by MSP plot (Fig. 5.44). The relative proportions of AOM, phytoclasts (opaques and translucent) and palynomorphs components in PT-B infers an inner neritic/nearshore depositional environment under dysoxic-suboxic conditions. Kerogen Type: PT-B is characterized by kerogen type III or II (gas prone) based on the abundance of AOM, phytoclasts and palynomorphs (mainly of terrestrial origin). 196 University of Ghana http://ugspace.ug.edu.gh Figure 5.42: (a) Representative palynofacies association of PT-B, sample depth 3790m from the Dzata-2A well. Key to labels: AOM = amorphous organic matter, SP = sporomorph, DC = dinoflagellate cysts, OP = opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-B from Dzata-2A well. 197 University of Ghana http://ugspace.ug.edu.gh Figure 5.43: APP Ternary diagram for PT-B samples from Dzata-2A well (after Tyson, 1993). Figure 5.44: MSP Ternary plot for PT-B samples from Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 198 University of Ghana http://ugspace.ug.edu.gh 5.2.3.3 Palynofacies type 3 (PT-C) (AOM dominant with high palynomorphs) (Fig. 5.45a). PT-C is recognized between sample depths 3530 – 3396 m and 2580 – 2420 m. AOM dominates the total organic matter composition of this palynofacies by 64%. The palynomorphs group (22%) of POM dominated by sporomorphs from interval 3530 m – 3396 m and marine components from interval 2580 m – 2420 m altogether with low counts of opaques and translucent phytoclasts (6% and 8%) respectively (Fig. 5.45b; Fig 5.58). Palaeoenvironmental interpretation: This palynofacies association (PT-C) plots in the field VIII of Tyson’s APP diagram which indicates deposition in a distal dysoxic-oxic shelf (Fig. 5.46). Tyson (1995) suggested that preservation of AOM is enhanced when the site of deposition is located relatively far from high terrestrial organic matter input with prevailing reducing conditions. Palynomorphs of terrestrial origin are dominated by sphaeroidal gymnosperm pollen grains (e.g. Classopollis, Araucariacites) which constitute 97% of the palynomorphs which is recorded between sample intervals 3530 – 3396 m. The samples from intervals of the topmost section of the well (2580 – 2420 m) are dominated by marine palynomorphs (av. 85%) of total palynomorphs. The marine elements are primarily dominated by chorate gonyaulacoids (90%) over the cavate peridinoids (10%) of total marine palynomorphs (Fig. 5.57). Open marine gonyaulacoid chorate cysts such as Oligosphaeridium complex, Florentina mantellii, Spiniferites spp. and Cordosphaeridium multispinosum recovered from the interval (2580 m – 2420 m) suggests a more offshore (middle-outer neritic) depositional environment. Intervals from 3530 m – 3396 m is dominated by sporomorphs (mainly sphaeroidal gymnosperm pollen grains (97%)), few pteridophytes (e.g. Cyathidites, Deltoidspora, etc.) with associated constituents of POM which depicts a nearshore/inner neritic depositional environment. The transition of depositional environment of PT-C from nearshore/inner neritic to open marine (middle-outer neritic) is supported by MSP plot (Fig. 5.47). The low amounts of phytoclasts are equated to weak terrestrial influx and deposition in 199 University of Ghana http://ugspace.ug.edu.gh distal settings located far from land vegetation (Muller, 1959; Pocklington and Leonard, 1979; Tyson, 1993). Based on the above discussion, PT-C is deposited in a distal dysoxic-oxic shelf conditions from a nearshore/inner neritic environment between sample depth 3530-3396 m and a middle-outer neritic environment for samples between 2580-2420 m. Kerogen Type: This field is characterized by kerogen type II>I (oil prone) based on the dominant well preserved AOM with high palynomorphs (av. dominated by marine elements). 200 University of Ghana http://ugspace.ug.edu.gh Figure 5.45: (a) Representative photograph of palynofacies association PT-C, sample depth 2580m from the Dzata-2A well. Key to label: SP = sporomorph. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-C from Dzata-2A well. 201 University of Ghana http://ugspace.ug.edu.gh Figure 5.46. APP Ternary diagram for PT-C samples from Dzata-2A well (after Tyson, 1993). Figure 5.47: MSP Ternary plot for PT-C samples from Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 202 University of Ghana http://ugspace.ug.edu.gh 5.2.3.4 Palynofacies type 4 (PT-D) (Abundance of AOM and opaque phytoclasts with high translucent phytoclasts) (Fig. 5.48a). PT-D occurs between sample depths from 3375 m – 3168 m. It is made up of relative abundance of AOM (37%), opaques (32%), phytoclasts (23%) and palynomorphs (8%) of total POM (Fig. 5.48b). Palynomorphs of terrestrial origin (sphaeroidal pollen grains) dominates the assemblage and contributing 99% of total palynomorphs and similar to those recovered in PT- B (Fig. 5.58). Generally the palynomorphs are orange to pale brownish in colour with the translucent phytoclasts consisting mainly of pale brown. The opaque phytoclasts are dark brown to black in colour. Palaeoenvironmental interpretation: On Tyson’s APP ternary diagram, PT-D plots in field II which reflects marginal dysoxic-anoxic basin conditions (Fig. 5.49). Recovered sporomorphs in this palynofacies type include Classopollis spp, Ephedripites spp., Elaterosporites spp. with associated taxa of Retimonocolpites, Araucariacites and Cyathidites. Pteridophytic spore assemblages (e.g. Cyathidites, Deltoidspora) are low to none in occurrence for most of these intervals. Sporomorphs dominated by sphaeroidal pollen grains occurrence and relatively abundant phytoclasts (opaques and translucent) suggests a nearshore environment and supported by MSP plot (Fig 5.50). Based on the discussions above with POM constituents, palynofacies type 4 (PT-D) indicates a nearshore/inner neritic depositional environment under marginal dysoxic anoxic basin conditions. Kerogen Type: PT-D is constituted by kerogen type III (gas prone) based on abundant AOM and opaque phytoclast with high translucent phytoclasts. 203 University of Ghana http://ugspace.ug.edu.gh Figure 5.48: (a) Representative photograph of palynofacies association PT-D, sample depth 3312m from the Dzata-2A well. Key to labels: AOM = amorphous organic matter, OP = opaque phytoclast. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-D from Dzata-2A well. 204 University of Ghana http://ugspace.ug.edu.gh Figure 5.49. APP Ternary diagram for PT-D samples from Dzata-2A well (after Tyson, 1993). Figure 5.50: MSP Ternary plot for PT-D samples from Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 205 University of Ghana http://ugspace.ug.edu.gh 5.2.3.5 Palynofacies type 5 (PT-E) (AOM dominant) (5.51a). PT-E facies occurs between sample depths 3147 – 3105 m and 2943 – 2600 m. It is characterized by very high AOM (81%) of the total organic matter composition with very little proportions of opaques, translucent phytoclasts and palynomorphs (6%, 8% and 5%) respectively (Fig. 5.51b). AOM preservation is good and pale yellow to orange in colour. Sample intervals from 3147m-3105m is constituted by 98% sporomorphs (dominated by sphaeroidal pollen grains of total palynomorphs of POM (5%)) while sample intervals from 2943m-2600m is composed of 78% marine palynomorphs from total palynomorphs (dominated by 93% chorate gonyaulacoid cysts (Fig. 5.57) with the remaining 22% being sporomorphs (dominated by sphaeroidal pollen grains) (Fig. 5.58). Palaeoenvironmental interpretation: PT-E plotted in field IX of Tyson’s APP ternary which indicates a deposition in a distal suboxic-anoxic basin condition (Fig. 5.52). Common gonyaulacoid cysts recovered in interval 2943 m – 2600 m include the genus of Spiniferites, Trichodinium and Oligosphaeridium with minor occurrence of peridinoids (Andalusiella, Palaeocystodinium and Cerodinium). Sphaeroidal pollen grains recorded in higher amounts than pteridophyte spores from 2943 m – 2600 m. Intervals from 3147 m – 3105 m generally recorded low to none amount of pteridophytes throughout this palynofacies type with occurrence of pollen of palmae (e.g. Proxapertites and Longapertites) which flourish in mangrove environments alongside coastal areas of humid tropics (Schrank, 1998; Herngreen, 1998; El Beialy, 1995). The low occurrence of phytoclasts which supports the offshore depositional environment for PT-E (Fig. 5.53). Dominant AOM (>60%) of POM recorded indicates reducing conditions and increased water column stability (Tyson, 1995; Ibrahim et al., 2002). Based on discussions above and constituents of POM together with associated palynomorphs, PT-E must have been deposited from inner to middle neritic environment at depths intervals 206 University of Ghana http://ugspace.ug.edu.gh 3147 m – 3105 m to middle-outer neritic environment at 2943 m – 2600 m under distal suboxic- anoxic basin condition. Kerogen Type: characterized by kerogen type II≥I (highly oil prone) based on the dominance of well-preserved AOM. Figure 5.51: (a) Representative photograph of palynofacies association PT-E, sample depth 2880m from the Dzata-2A well. Key to label: AOM = amorphous organic matter. (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-E from Dzata-2A well. 207 University of Ghana http://ugspace.ug.edu.gh Figure 5.52: APP Ternary diagram for PT-E samples from Dzata-2A well (after Tyson, 1993). Figure 5.53: MSP Ternary plot for PT-E samples from the Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 208 University of Ghana http://ugspace.ug.edu.gh 5.2.3.6 Palynofacies type 6 (PT-F) (AOM dominant with relatively equal abundance of translucent phytoclasts and palynomorphs) (Fig. 5.54a). PT-F is recorded at sample depths between 3084 - 2964 m. AOM (57%) dominates this palynofacies with relatively equal amount of phytoclasts and palynomorphs (17% and 18%) respectively and opaque phytoclasts (8%) of POM (Fig. 5.54b). AOM recovered is pale yellowish to orange in colour with good preservation. Palynomorphs recovered are wholly of terrestrial origin (mainly sphaeroidal forms). Palaeoenvironmental interpretation: PT-F plots in the field VII of Tyson’s APP diagram indicating deposition in a distal dysoxic-anoxic shelf environment (Fig. 5.55). The sporomorphs dominated by sphaeroidal pollen grains (e.g. Classopollis) with minor associated pteridophytes (e.g. Cyathidites). According to Kholeif and Ibrahim (2010), the very low occurrence of opaque phytoclasts suggests low salinity due to close proximity to fluvio-deltaic sources. The POM and its associated palynomorphs infers a nearshore/shallow marine depositional environment supported by MSP ternary diagram (Fig. 5.56). The discussion above suggests PT-F must have been deposited in a nearshore/shallow marine environment under a distal dysoxic-anoxic shelf environment. Kerogen Types: The samples of PT-F are characterized by kerogen type II/III (oil prone) based on the dominant AOM relatively terrestrial palynomorphs. 209 University of Ghana http://ugspace.ug.edu.gh Figure 5.54: (a) Representative photograph of palynofacies association PT-F, sample depth 3042m from the Dzata-2A well. Key to labels: AOM = amorphous organic matter, SP = sporomorph (b) Pie chart showing relative abundance (%) of the different constituents of palynofacies association PT-F from Dzata-2A well. 210 University of Ghana http://ugspace.ug.edu.gh Figure 5.55. APP Ternary diagram for PT-F samples from Dzata-2A well (after Tyson, 1993). Figure 5.56: MSP Ternary plot for PT-F samples from Dzata-2A well (After Federova, 1977; Duringer and Doubinger, 1985). 211 University of Ghana http://ugspace.ug.edu.gh Figure 5.57: Relative percentage composition of Gonyaulacoids and Peridinoids of 5% total palynomorphs from Dzata-2A well. 212 University of Ghana http://ugspace.ug.edu.gh PT- E PT- E Figure 5.58: Palynofacies associations showing POM (%) from Dzata-2A well. 213 University of Ghana http://ugspace.ug.edu.gh CHAPTER SIX SOURCE ROCK EVALUATION 6.1 INTRODUCTION Hunt (1995) define petroleum source rock as the fine-grained sediment with enough organic matter, which can generate and release enough hydrocarbons to form a commercial accumulation of oil or gas. He categorized source rocks according to oil generation into three classes which are; immature source rocks that have not yet generated hydrocarbons; mature source rocks that are in generation phase; post mature source rocks which are those that have already generated all crude oil type hydrocarbons. Common source rocks are normally shales and limestones, which contain significant amount of organic matter (Tissot and Welte, 1984). Tissot and Welte (1984) enumerated the key analyses that have to be carried out in a source rock evaluation for hydrocarbon potential which includes the amount (total organic carbon content), type (oil or gas prone material) and the level of thermal maturation (immature or mature) of organic mature in sediments. Pyrolysis is almost the best routine tool for determining the kerogen type and maturity (Espitalié et al., 1977) According to Allen & Allen (1990) and Hunt (1996), hydrocarbons are generated in source rocks by the thermal alteration of organic matter with increasing depth of burial that increases temperature with time. Vitrinite reflectance (Ro) is one method of evaluating the thermal alteration of sedimentary rocks (Héroux et al., 1979) which successfully demonstrated to be a reliable indicator of organic maturation in sedimentary successions widely used in the oil industry to define potential areas of petroleum generation in a basin (Peters and Cassa 1994). 214 University of Ghana http://ugspace.ug.edu.gh 6.2 METHODOLOGY The geochemical data of Lynx-X and Dzata-2A wells were obtained from the Core Laboratory of Ghana National Petroleum Corporation. Results were obtained for 120 and 101 samples from Lynx-1X and Dzata-2A wells respectively. The results were derived from the standard preparation and analysis for total organic carbon, Rock-Eval pyrolysis and vitrinite reflectance measurements to evaluate the hydrocarbon source potential. Samples were obtained using sampling interval of 20m. Analyses were done on the results of the pyrolysis data obtained following the guidelines in table 6.1 and discussed below. Geological information as well as the rock eval data is displayed in (Appendix 7 and 8). Data from Rock-eval pyrolysis, total organic carbon and vitrinite reflectance measurements which were subjected to scatter plots for source rock evaluation with the view of identifying the type, richness, quality and thermal maturity of source rock samples. Scatter plots are cross plots whereby the parameters obtained from pyrolysis are plotted against each other and used in interpreting the properties and hydrocarbon potential of the area of study. The basic parameters obtained by Rock-Eval pyrolysis are: • S1=the amount of free hydrocarbons (gas and oil) in the sample (in milligrams of hydrocarbon per gram of rock). S1 normally increases with depth. Contamination of samples by drilling fluids and mud can give an abnormally high value for S1. • S2=the amount of hydrocarbons generated through thermal cracking of non-volatile organic matter. S2 is an indication of the quantity of hydrocarbons that the rock has the potential of producing should burial and maturation continue. • S3=the amount of CO2 (in milligrams CO2 per gram of rock) produced during pyrolysis of kerogen. S3 is an indication of the amount of oxygen in the kerogen and is used to calculate the oxygen index. 215 University of Ghana http://ugspace.ug.edu.gh • Tmax = the temperature at which the maximum release of hydrocarbons from cracking of kerogen occurs during pyrolysis (top of S2 peak). Tmax is an indication of the stage of maturation of the organic matter. • TOC = total organic carbon content of samples, were determined by adding the residual organic carbon detected in pyrolysis residues to the pyrolyzed organic carbon, which in turn is measured from the hydrocarbon compounds issuing from pyrolysis. The following parameters were calculated from Rock Eval pyrolysis data: • Hydrogen Index (HI) = [100 x S2]/TOC). HI is a parameter used to characterize the origin of organic matter. Marine organisms and algae, in general, are composed of lipid- and protein-rich organic matter, where the ratio of H to C is higher than in the carbohydrate-rich constituents of land plants. • Oxygen Index (OI) = [100 x S3]/TOC). OI is a parameter that correlates with the ratio of O to C, which is high for polysacharride-rich remains of land plants and inert organic material (Tissot and Welte, 1984). • Production Index (PI) = S1/ [S1 + S2]). PI is used to characterize the evolution level of the organic matter. • The vitrinite reflectance (Ro) was estimated from the Tmax values obtained from the Rock-Eval pyrolysis (Dembicki Jr., 2009) and expressed mathematically as: Rcalculated = (0.018 ⁄ Tmax) 7.16. Table 6.1 below serve as a guide for interpretation of the source rock potential of the study area. Cross plots of the various parameters were done using softwares such as Microsoft excel, Delta graph, Corel draw and Inkscape app. 216 University of Ghana http://ugspace.ug.edu.gh Table 6.1. Guidelines for interpreting source rock quantity, quality and maturation, and commonly used Rock-Eval parameters. S1(mg HC/g Quantity TOC S2(mg HC/g rock) rock) Poor <0.5 <0.5 <2.5 Fair 0.5-1 0.5-1 2.5-5.0 Good 1-2 1-2 5-10 Very Good 2-4 2-4 10-20 Excellent >4 >4 >20 HI (mg HC/g Quality S2/S3 Kerogen Type TOC) None <50 <1 IV Gas 50-200 1-5 III Gas and Oil 200-300 5-10 II/III Oil 300-600 10-15 II Oil >600 >15 I 0 Maturation Ro (%) Tmax ( C) TAI Immature 0.2-0.6 <435 1.5-2.6 Early Mature 0.6-0.65 435-445 2.6-2.6 Peak Mature 0.65-0.9 445-450 2.7-2.9 Late Mature 0.9-1.35 450-470 2.9-3.3 Post Mature >1.35 >470 >3.3 SOURCE: {Epstein et al. (1977), Espitalié et al. (1984), Peters (1986), Traverse (1988), Peters and Cassa (1994), Fowler et al. (2005)} 217 University of Ghana http://ugspace.ug.edu.gh 6.3 EVALUATION OF LYNX-1X AND DZATA-2A WELLS 6.3.1 Organic Carbon richness and Hydrocarbon Potential Batten (1996) stated that for a rock to be a hydrocarbon source, that particular rock should have had a sufficient amount of organic matter for the generation and the expulsion. Peters (1986) used the measure of pyrolysis derived S2 of the rock samples and TOC to determine the source rock richness and hydrocarbon potentiality. The organic richness of samples containing TOC (wt%) under 0.5% are classified as poor, 0.5 to 1.0% TOC are fair, and those containing over 1.0% TOC are a good source. Samples which contain S2 under 2.5 mg/g are poor source rocks, S2 from 2.5 to 5 mg/g are fair source rocks, S2 from 5-10 mg/g are good source rocks, and those with more than S2>10 mg/g are viewed as very good source rocks (Table 6.1). Analysed samples from Lynx-1X well have organic carbon (TOC) ranges from 0.5-6.0 wt% (Fig. 6.1, Appendix 7). Samples of the Paleocene-Eocene (2525 – 2755 m) have TOC (wt%) ranging from 0.53-1.63 wt% which reflects organic richness from fair to good source rocks and with S2 values (0.25-3.82mg/g) indicating poor to fair source potential (Fig. 6.1). The Campanian-Maastrichtian rocks (2775-3305 m) is characterized by TOC (wt%) values from 1.19-4.15 wt% which indicates good to excellent organic source richness and characterized by S2 values (2.54-6.58mg/g) which reflects fair to good source potential (Fig. 6.1). The Turonian- Santonian? rocks (3325-3695 m) have TOC values (1.58-3.08 wt%) which denotes good to very good source rock. The S2 values ranges from 4.67-18.93 mg/g which indicates good to very good source potential (Fig. 7.1). Albian-Cenomanian rocks (3715 - 5297.5 m) has TOC values ranging from 0.51-6.48 wt% which reflects fair to excellent source rock with most of the measured intervals indicating fair to very good organic richness. The hydrocarbon potentiality characterized by S2 values which ranges from 0.2-8.68 mg/g demonstrates poor to good source potential (Fig. 6.1). 218 University of Ghana http://ugspace.ug.edu.gh Analysed samples from Dzata-2A well have organic carbon (TOC) ranging from 0.6-6.0 wt% (Appendix 8). The Campanian-Maastrichtian rocks (2418-2420 m) - (2781-2784 m) have organic carbon (TOC) values ranging from 1.67-6.1 wt% which is considered as good to excellent organic source richness. The S2 values ranging 3.33-27.37 mg/g indicates good to excellent source potential. Measured intervals from the Turonian-Santonian? rocks ((2799- 2802 m) - (2919-2922 m)) have TOC values (1.97-4.02 wt%), reflecting good to excellent source rocks with intervals having good to very good organic richness. The S2 values recorded range from 7.94-21.28 mg/g denoting good to excellent hydrocarbon potentiality. Samples from the Albian-Cenomanian source rocks ((2940-2943 m) - (4170-4180 m)) have organic carbon (TOC) values which range from 0.51-1.86 wt% which is reflective of a fair to good organic richness. S2 values ranges from 0.25-4.48 mg/g indicating a fair source potential. The Rock-Eval pyrolysis for both wells indicate that 70-80% of analysed samples are good to very good potential source rock. However, greater than 50% of the samples have S2 values less than 10mg/g which suggest a good hydrocarbon potentiality for Lynx-1X and Dzata-2A wells (Fig. 6.1). S2 which measures the existing potential of a rock to generate hydrocarbons is considered as a more practical metric of source rock potential than the TOC since the TOC includes “dead carbon” which is unable to generate hydrocarbons (Peters and Cassa 1994; Alaug et al., 2014). Therefore, ?Turonian-Santonian age samples in the studied wells are considered as better potential source rocks than the Campanian-Maastrichtian and Albian- Cenomanian source rocks. 219 University of Ghana http://ugspace.ug.edu.gh Figure 6.1: S2 against TOC% showing the Hydrocarbon potentiality and source efficiency The plot of S2 against TOC% (Fig. 6.2) was also used to deduce the kerogen types of the studied samples from Lynx-X and Dzata-2A wells. The plot showed that majority of the samples plotted between Kerogen type II and III which indicate oil and gas prone hydrocarbons (Fig. 6.2). Few of the samples plotted in Type I (Oil) in Lynx-well and type IV Kerogen zone for both wells. 220 University of Ghana http://ugspace.ug.edu.gh Figure 6.2: S2 against TOC% plot showing types of kerogens In this study, the plot of HI/TOC for Lynx-1X and Dzata-2A wells combines generation potential and kerogen types (Fig. 6.3). With respect to TOC, four samples in both wells plotted within excellent generation potential. Majority of the samples plotted within 1-4% TOC which indicates a good to very good generation potential. According to Tissot and Welte (1984), the Genetic Potential (S1 + S2) of a given formation is the amount of petroleum (oil and gas) that kerogen is able to generate if it is subjected to an adequate temperature during a sufficient interval of time. It gives a qualitative estimate of hydrocarbon resource potential but cannot be used to predict the type of hydrocarbons (i.e gaseous or liquid) that will be produced during pyrolysis. Waples et al (1992) intimated that, a rock with Genetic Potential less than 2 mgHC/g rock represents a gas prone or non-generative zone. However, the values between 2-6 mgHC/g rock is representative of a moderate source rock with fair oil and gas generation potential and those with GP values higher than 6 mgHC/g rock indicates a good source rock. Rocks which have extremely high GP values of about 100- 221 University of Ghana http://ugspace.ug.edu.gh 200 mgHC/g rock would provide either an excellent source rock with enough burial depth or an oil shale when burial depth is shallow. With reference to Waples et al (1992) stated above, analysed samples from the Paleocene- Eocene sediments in Lynx-1X well with GP values ranging from 0.35-3.96 mgHC/g rock is indicative of a gas/non-generative zone to a moderate source with fair oil and gas generation potential and supported by the very low TOC values (0.53-1.63) (Fig. 6.4). The Campanian- Maastrichtian rocks GP of Lynx-1X (2.66 - 26.78 mgHC/g rock) and Dzata-2A (3.45 - 27.66 mgHC/g rock) represents moderate source rock with fair oil and gas generation potential to a good source rock. Most of the very high TOC values ((1.19-4.15) and (1.67-6.1)) for Lynx-1X and Dzata-2A wells respectively in these sample intervals further assign a good source (Fig. 6.4). The ?Turonian-Santonian rocks of Lynx-1X with GP values (4.78 - 19.1 mgHC/g rock) and Dzata-2A (8.03-21.46) which represents moderate to good source supported by high TOC content (1.58-3.08) and (1.97-4.02)) for Lynx-1X and Dzata-2A respectively for majority of the samples ranging from good to very good organic richness and fair hydrocarbon potentiality for S1 values (0.11-0.18 for Lynx-1X and 0.8-0.18 for Dzata-2A) (Fig. 6.4). Analysed samples from the Albian-Cenomanian rocks are characterized by the lowest GP values. For Lynx-1X well GP value ranges from 0.25-15.23 mgHC/g rock and 0.3-4.62 mgHC/g rock for Dzata-2A well which represent a moderate to good source potential (Fig. 6.4). The hydrocarbon potential of the study succession in both wells suggests a fair to very good. 222 University of Ghana http://ugspace.ug.edu.gh Figure 6.3: Plot of Hydrogen Index against TOC% indicating kerogen types and generation potential. Figure 6.4: Plot of GP (S1+S2) against TOC% indicating hydrocarbon potentiality for the well samples. 223 University of Ghana http://ugspace.ug.edu.gh 6.3.2 Kerogen Types Kerogen or organic matter type is important in evaluating source rock potential and essentially has a first order control on the nature of the hydrocarbons. Kerogen types are normally identified by optical and by organic geochemical methods by plotting the values of elemental analysis of C, O, H on the Van Krevelen diagram which defines the four types of kerogens (Peters and Cassa 1994; Tissot et al., 1974). Hydrogen indices values (HI) were used to differentiate between the types of organic matter (Epstein et al., 1977; Espitalié et al., 1984; Waples, 1985; Peters, 1986; Traverse, 1988; Peters and Cassa, 1994; Fowler et al., 2005). With reference to Table 6.1, HI values lower than 50 mg/g contains kerogen type IV with no potential source; 50-200 mg/g values is a potential source for generating gas (type III kerogen); 200-300 mg/g values comprise more of type III kerogen than type II which is capable of generating mixed oil and gas but mainly gas; 300-600 mg/g values consist of type II kerogen and indicates a good source potential for generating oil with minor gas; HI values greater than 600 mg/g contains mainly kerogen Type I with excellent potential to generate oil. Analysed samples from Lynx-1X well in this study have HI values which ranges from 42-326 mg/g and OI values from 24-99 mg/g (Appendix 7) for the Paleocene-Eocene samples which is represented by eight samples and indicates no potential (kerogen type IV) to good source potential for generating oil and gas (type II, III) but mainly gas (Fig. 6.5). In the Campanian- Maastrichtian the twenty-eight samples have HI values ranging from 197-641 mg/g and OI values from 13-35 mg/g (Appendix 7). These values reflect potential source for generating gas (type III kerogen) to excellent potential of generating oil (Kerogen type I). The majority of the samples plot in type II and III kerogen zone (Fig. 6.5). Twenty-one samples analysed from the ?Turonian-Santonian is represented by HI values (290-614 mg/g) and OI values (14-37 mg/g) where most of the samples belong to type II and III kerogen capable of generating oil and gas (Fig. 6.5). HI values range from 20-471 mg/g and OI values range from 9-88 mg/g of the 224 University of Ghana http://ugspace.ug.edu.gh Albian-Cenomanian analysed samples (63) reveal kerogen types IV, III, II/III and II where majority of the samples plot in kerogen types II/III and III which is considered to generate oil and gas but mainly gas (Fig. 6.5). The Dzata-2A well has HI and OI values ranging from 188-449 mg/g and 15-43 mg/g respectively for the Campanian-Maastrichtian (20 samples), reflecting types III, II/III and II kerogens (Fig. 6.5). Most of the samples contains more type III than II kerogen which is a good source for generating more gas than oil. The seven samples analysed from ?Turonian-Santonian has HI values ranging from 357-530 mg/g and OI values ranging from 14-23 mg/g which is characterized by type II kerogen and is considered a good source potential for generating oil. In the Albian-Cenomanian, 74 samples were analysed and HI values of range (34-256 mg/g) and OI values ranging from 23-118 mg/g (Appendix 8) were recorded. This indicates kerogen Types IV, III and II/III. Majority of the samples plot in kerogen type III which is a potential source capable of generating gas with few samples concentrating in kerogen type II/III which indicates potential for generating oil and gas but mainly gas (Fig. 6.5). The sample plots of HI versus Tmax also displayed similar trends and identified the kerogen types observed in the plot of HI versus OI for Lynx-1X and Dzata-2A wells (Figs. 6.6, 6.7). From the above discussion, the ?Turonian-Santonian analysed samples of Lynx-1X and Dzata- 2A wells have good potential to generate oil/gas than the Albian-Cenomanian, Campanian- Maastrichtian and Paleocene-Eocene studied intervals. 225 University of Ghana http://ugspace.ug.edu.gh Figure 6.5: Types of kerogens indicated on a modified Van Krevelen diagram Figure 6.6: Types of kerogen and levels of maturity shown by Hydrogen Index against Tmax 226 University of Ghana http://ugspace.ug.edu.gh Figure 6.7: Types of kerogen and levels of maturity shown by Hydrogen Index against Tmax 6.3.3 Organic Matter Maturity The maturity of the source rock is another important factor of source rock evaluation. The level of thermal maturity for the different types of organic matter may be estimated from the Tmax range and Production Index (Peters and Cassa, 1994; Bacon et al., 2000; El Kammer, 2015). Organic matter maturity is determined by using the level of thermal maturity of organic matter and type of organic matter which influences the type of maturity as well as the presence of free hydrocarbons with other factors which includes content, burial depth, and mineral water (Traverse, 1988). According to Traverse (1988), an increase in maturity level of organic matter corresponds to an increase in Tmax particularly for immature samples. 227 University of Ghana http://ugspace.ug.edu.gh The plots of HI/Tmax from the analysed samples of Lynx-1X and Dzata-2A made it possible to define the kerogen type based on HI only since the variability in Tmax is confined to 409-476 oC for Lynx-1X well and 416-449 oC for Dzata-2A well. In the present study, the thermal maturity level of the source rocks was determined by the study of Tmax, production index (PI), and vitrinite reflectance (Rcalculated). According to Peters et al. (2005), Rcalculated formula (0.018 ⁄ Tmax) 7.16) is applicable for type II and type III kerogen and reasonable when the analysed samples have S2 values more than 0.5 mg HC/g rock and Tmax <420 oC or >500 oC which is consistent with majority of the analysed samples in this study. According to Peters (1986), oil generation from source rocks began at Tmax 435-465°C, PI values ranging from 0.2-0.4% and vitrinite reflectance (Ro%) greater than 0.6%. Tmax values less than 435°C, PI values less than 0.2% and Ro values less than 0.6% of organic matters are considered to be immature. The gas generation from source rocks started at Tmax 470°C, PI greater than 0.4% and Ro more than 0.8%. Analysed samples for Lynx-1X and Dzata-2A wells in this study shows majority of the samples have PI values between 0.1 and 0.2 and Tmax values ranging from 410-460oC, indicating that most of the samples (Tmax < 435oC) are immature with few samples having PI>0.2 and Tmax > 435oC indicating early mature to mature organic matter (Oil window) (Figs. 6.8, 6.9). Most of the analysed samples have low level of kerogen conversion (Fig. 6.9). A plot of HI/Tmax (Figs. 6.6, 6.7) is also consistent with majority of the analysed samples plotting outside the oil window with few samples constrained in the condensate-wet gas zone (Fig. 6.7). (Rcalculated) values of samples from Lynx-1X and Dzata-2A indicate immature to early mature (Fig. 10), since most of the samples show Rcalculated values less than 0.6 (Appendix 7 & 8) and increases with depth (Fig. 11). Lynx-1X has most part of the deeper analysed sample intervals to be inconsistent with the decreasing Rcalculated trend with depth plot (Fig. 11) because most of the samples below 4700 m have S2 values less than 0.5 mg/g and Tmax values greater than 420oC 228 University of Ghana http://ugspace.ug.edu.gh and less than 500oC (Appendix 7). Tmax and Rcalculated versus the Hydrogen Index (HI) cross plot after Espitalié (1986) gives an overview of the thermal maturity and variation of organic matter quality. Lynx-1X and Dzata-2A wells have Tmax values correlates directly with the vitrinite reflectance values (Figs. 6.7, 6.12). Figure 6.8: Plot of Tmax versus Production Index showing hydrocarbon generation zone. 229 University of Ghana http://ugspace.ug.edu.gh Figure 6.9: Plot of Production Index versus Tmax showing levels of kerogen conversion and maturity Figure 6.10: Plot of Tmax versus Vitrinite reflectance (Ro) showing maturity levels 230 University of Ghana http://ugspace.ug.edu.gh Figure 6.11: Plot of depths versus vitrinite reflectance data (Rcalculated) showing thermal maturity stages of Lynx-1X and Dzata-2A wells. 231 University of Ghana http://ugspace.ug.edu.gh Figure 6.12: Vitrinite reflectance (Rcalculated) versus the Hydrogen Index (HI) showing variation of organic matter quality from Lynx-1X and Dzata-2A wells. 6.3.4 Expulsion Potential Peters et al., (2006) proposed that the maturity at which the Bituminous Index (BI) = S1/TOC value begins to decline represents the start of an efficient oil window or indicate efficient oil expulsion. Lewan (1997) proposed that, the compounds generated in the early stages are presumed to be Bitumen or heavy crude oil which later forms lighter oils by partial decomposition at higher maturity. During maturity, S2 is continuously decomposing, causing a decrease in S2 and an increase in free Hydrocarbon (S1) and further increasing BI. According to Hunt (2000), the Ocean Drilling Program used S1/TOC of 1.5 to determine the presence of indigenous versus migrated or non-indigenous hydrocarbon levels. 232 University of Ghana http://ugspace.ug.edu.gh S1 versus Total Organic Carbon (TOC) plot indicates that, part of the source rock contains S1 hydrocarbons for their given Total Organic Carbon (TOC) making them indigenous (Fig. 6.13), however, in this study very little part of the source rock shows non-indigenous and as such have been expelled from another source (Nady et al., 2014). Figure 6.13: S1 versus TOC as an indicator of indigenous and non-indigenous hydrocarbons 233 University of Ghana http://ugspace.ug.edu.gh CHAPTER SEVEN CONCLUSION Analyzed samples from the Middle Cretaceous to Early Tertiary from three oil wells (Lynx- 1X, Dzata-1 & Dzata-2A) in the Deepwater Cape Three Points, offshore Tano, Western Ghana are constituted by rich palynoflora (sporomorphs and dinoflagellate cysts). Based on the First Appearance Datum (FAD) and Last Appearance Datum (LAD) of stratigraphically significant species, four palynozones (PZ-I to PZ-IV) and nine subzones are proposed for the samples. These palynozones and subzones are; PZ-I: Afropollis jardinus-Sofrepites legouxae-Elaterocolpites castelaini Assemblage Zone; Subzone 1: Afropollis jardinus-Elaterosporites klaszii Interval Zone Subzone 2: Elaterocolpites castelaini Interval Zone Subzone 3: Elateroplicites africaensis Interval Zone Subzone 4: Galeocornea causea Interval Zone PZ-II: Cretaceaeiporites polygonalis-C. scabratus-Dinogymnium accuminatum Assemblage Zone PZ-III: Trichodinium castanea-Cerodinium diebelli-Dinogymnium acuminatum Assemblage Zone; Subzone 1: Trichodinium castanea Interval Zone Subzone 2: Dinogymnium acuminatum Interval Zone PZ-IV: Cerodinium diebelli-Apectodinium homomorphum- Homotryblium tenuispinosum Assemblage Zone; Subzone 1: Andalusiella polymorpha Interval Zone Subzone 2: Homotryblium tenuispinosum Interval Zone Subzone 3: Apectodinium homomorphum Interval Zone 234 University of Ghana http://ugspace.ug.edu.gh Ages proposed for the palynozones are based on similar stratigraphic significant taxa published and recovered by other workers from sediments from other parts of the northern and southern hemispheres which ranges from Albian-Eocene. Lynx-1X is dated from the Albian-Eocene, however Dzata-1 and Dzata-2A wells are dated as Albian-Maastrichtian age. Distribution of palynomorphs enabled the identification of two major sedimentary facies which are the nearshore and open marine facies. The nearshore facies concentrated at deeper parts of wells are characterized by abundant sporomorphs and peridinoid dinocysts while the open marine facies are dominated by gonyaulacoid dinocysts and are restricted to the shallower parts of the wells. This occurred as a result of marine transgression which flooded the area causing marine sedimentation. The Albian-Cenomanian (PZ-I) sediments reflected arid/semi-arid environment due to the presence of Classopollis and Ephedroids. The abundance of peridinoids dinocysts (Cerodinium, Andalusiella, Paleocystodinium, Phelodinium) over the gonyaulacoid dinocysts (Spiniferites, Glaphyrocysta/Areoligera, Cordosphaeridium) at level 2800-2720m in Lynx-1X and moderate sporomorphs in the Maastrichtian connotes a nearshore/inner neritic environment. The open marine (middle-outer neritic) sediments are constituted by dominant gonyaulacoid dinocysts over peridinoid dinocysts and sporomorphs which is recognized in the Campanian-Maastrichtian of Dzata-1 and Dzata-2A wells and in the Campanian and Paleocene-Eocene of Lynx-1X well which was as a result of transgression in the area that provided conditions favorable for the development of dominant marine palynoflora. The sporomorphs diversity in the Campanian-Eocene sediments indicates variabilities in vegetational zones from mangrove (brackish) water to fresh water environment in a hot tropical climate. The sporomorphs associations recovered from Lynx-1X, Dzata-1 and Dzata-2A exhibit similarity to Cretaceous Phytogeographic Provinces of African-South America (ASA). 235 University of Ghana http://ugspace.ug.edu.gh Sporomorphs characteristic of Albian-Cenomanian Elaterate Province for the deeper intervals (PZ-I and II) and of the Senonian Palmae Province for the shallower intervals (PZ-III and IV) have been recognized for all the wells. The Campanian-Eocene peridineacean assemblage (Cerodinium, Andalusiella, Paleocystodinium, Phelodinium) has a lot of similarity with those of Malloy or Tropical/Subtropical suite of Lentin and Williams (1980). Palynofacies analysis revealed Seven (7) palynofacies associations (PF-1 to PF-7) for Lynx- 1X well. PF-1 reflects deposition in a fluvio-deltaic/nearshore environment under a marginal dysoxic-anoxic basin condition with sediments typical of kerogen type III-IV (gas prone). PF- 2 is deposited under a proximal suboxic-anoxic shelf conditions in a marginal marine/nearshore environment and sediments classified as kerogen type II/III (gas prone). PF-3 suggest a deposition which took place in a marginal marine to shallow marine environment under distal suboxic-anoxic conditions and constituted by kerogen type II>I (highly oil prone). PF-4 is suggested to be deposited under a distal suboxic-anoxic basin condition in a shallow marine environment and sediments characterized by kerogen type II>I (highly oil prone). PF-5 indicates a deposition under a distal dysoxic-oxic shelf conditions in middle-outer neritic environment. PF-5 and sediments constituted by kerogen type II>I (oil prone). PF-6 suggests a deposition in a shelf to basin transition condition in an offshore, most likely from an inner- middle neritic environments and constituted by kerogen type III and II (oil prone). PF-7 supports an outer neritic environment under distal mud-dominated oxic shelf conditions and characterized by kerogen type II/III (gas prone). In Dzata-1 well, five palynofacies associations (PT-1-PT-5) were recognized. PT-1 suggests a deposition in a nearshore environment under proximal suboxic-anoxic conditions and sediments typical of kerogen type II and III (oil prone). PT-2 indicates a deposition in a dysoxic-suboxic conditions in a nearshore environment and constituted by kerogen type III 236 University of Ghana http://ugspace.ug.edu.gh (gas prone). PT-3 must have been deposited under a marginal dysoxic-anoxic basin condition in a fluvio-deltaic/nearshore environment with kerogens typical of Type III (gas prone). PF-4 suggests an inner-middle neritic environment to an outer neritic environment under distal dysoxic-oxic shelf conditions and kerogens classified as kerogen type II>I (oil prone). In PT- 5, a deposition of a nearshore environment under marginal dysoxic-anoxic basin conditions is inferred. It is characterized by kerogen type III (gas prone). Analyzed samples from Dzata-2A well revealed six palynofacies associations (PT-A-PT-F). PT-A indicates a deposition in a nearshore to shallow marine (inner neritic) environment under a proximal suboxic-anoxic shelf condition with typical Type II/III kerogen (oil prone). PT-B infers an inner neritic/nearshore depositional environment under dysoxic-suboxic conditions with facies characterized by kerogen type III or II (gas prone). PT-C is deposited under a distal dysoxic-oxic shelf conditions in a nearshore/inner neritic to middle-outer neritic environment. This field is characterized by kerogen type II>I (oil prone). PT-D indicates a nearshore/inner neritic depositional environment under marginal dysoxic anoxic basin conditions and facies constituted by kerogen type III (gas prone). PT-E must have been deposited from inner-outer neritic environment under distal suboxic-anoxic basin condition. These facies are characterized by kerogen type II≥I (highly oil prone). PT-F suggests a deposition in a nearshore/shallow marine environment under a distal dysoxic-anoxic shelf environment with facies characterized by kerogen type II/III (oil prone). Investigation of the hydrocarbon potential for Lynx-1X and Dzata-2A wells indicate that 70- 80% of analyzed samples are good to very good potential source rock. However, greater than 50% of the samples have S2 values less than 10 mg/g which suggest a good hydrocarbon potentiality for Lynx-1X and Dzata-2A wells. Therefore, the ?Turonian-Santonian age samples 237 University of Ghana http://ugspace.ug.edu.gh in the studied wells are considered as better potential source rocks than the Campanian-Eocene and Albian-Cenomanian source rocks. Analyzed samples from Lynx-1X well in this study have HI values which ranges from 42-326 mg/g and OI values from 24-99 mg/g for the Paleocene-Eocene samples indicates no potential (kerogen type IV) to good source potential for generating oil and gas (type II, III) but mainly gas. The Campanian-Maastrichtian samples have HI values ranging from 197-641 mg/g and OI values from 13-35 mg/g with majority of the samples constituted by type II and III kerogen which reflects potential source for generating oil and gas. Samples analyzed from the ?Turonian-Santonian is represented by HI values (290-614 mg/g) and OI values (14-37 mg/g) where most of the samples belong to types II and III kerogen capable of generating oil and gas. HI values range from 20-471 mg/g and OI values range from 9-88 mg/g for the Albian- Cenomanian analyzed samples which reveals majority of samples are characterized by kerogen types II/III and III which is considered to generate oil and gas but mainly gas. The Dzata-2A well has HI and OI values ranging from 188-449 mg/g and 15-43 mg/g respectively for the Campanian-Maastrichtian with most of the samples containing more type III than II kerogen which is a good source for generating more gas than oil. Analyzed samples from ?Turonian-Santonian has HI values ranging from 357-530 mg/g and OI values ranging from 14-23 mg/g which is characterized by type II kerogen and considered a good source potential for generating oil. In the Albian-Cenomanian samples, HI values of range (34-256 mg/g) and OI values ranging from 23-118 mg/g with majority of the samples constituted by kerogen type III which is a potential source capable of generating gas with few samples concentrating in kerogen type II/III which indicates potential for generating oil and gas but mainly gas. 238 University of Ghana http://ugspace.ug.edu.gh Conducting maturity analyses on samples indicates that Lynx-1X and Dzata-2A are considered to have majority of the samples being immature with few being organically matured in both wells and are generally of low kerogen conversion. In this study very little part of the source rock shows non-indigenous and as such have been expelled from another source. 239 University of Ghana http://ugspace.ug.edu.gh RECOMMENDATION Complete well log data and seismic data can be incorporated into future research which will further validate palynological results for research and petroleum exploration purposes. 240 University of Ghana http://ugspace.ug.edu.gh REFERENCES Abbink, O. A., Van Konijnenburg-Van Cittert, J. H. A., and Visscher, H. (2004). A sporomorph ecogroup model for the Northwest European Jurassic-Lower Cretaceous: concepts and framework. Netherlands Journal of Geosciences, 83(1), 17-31. ABD EL Ghany, E. S. (1992). Palynological zonation of Abu Roash G member and the upper part of Baharyia Formation in bed well N°. 1-2, Western Desert, Egypt. Abdel-Kireem, M. R., Schrank, E., Samir, A. M., and Ibrahim, M. I. A. (1996). 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Upper Campanian and Maastrichtian dinoflagellate cysts from the Maastricht region and Denmark [Ph.D. dissert.]. Nottingham Univ. Wilson, L.R and Hoffmeister, W. S. (1952). Small foraminifera. The Micropaleontologist, 6(2), 26-28. Wood, G. D., Miller, M. A., Sorer, Z., Krebs, W.N and Hedlund, R. W. (1997). Palynology, palynofacies, paleoenvironments and geochemistry of the lower cretaceous (pre-salt) Cocobeach group, north Gabon Subbasin, Gabon. Africa Geoscience Review, 4, 481- 498. Yepes, O. (2001). Maastrichtian‐Danian dinoflagellate cyst biostratigraphy and biogeography from two equatorial sections in Colombia and Venezuela. Palynology, 25(1), 217-249. Zobaa, M. K., El Beialy, S. Y., El-Sheikh, H.A and El Beshtawy, M. K. (2013). Jurassic- Cretaceous palynomorphs, palynofacies, and petroleum potential of the Sharib-1X and Ghoroud-1X wells, north Western Desert, Egypt. Journal of African Earth Sciences, 78, 51-65. 295 University of Ghana http://ugspace.ug.edu.gh APPENDICES Appendix 1: Distribution chart of the palynomorphs recovered from Lynx-1X well. 296 University of Ghana http://ugspace.ug.edu.gh Continued. 297 University of Ghana http://ugspace.ug.edu.gh Continued. 298 University of Ghana http://ugspace.ug.edu.gh Continued. 299 University of Ghana http://ugspace.ug.edu.gh Continued. 300 University of Ghana http://ugspace.ug.edu.gh Continued. 301 University of Ghana http://ugspace.ug.edu.gh Appendix 2: Distribution chart of the palynomorphs recovered from Dzata-1 well. 302 University of Ghana http://ugspace.ug.edu.gh Continued. 303 University of Ghana http://ugspace.ug.edu.gh Continued. 304 University of Ghana http://ugspace.ug.edu.gh Continued. 305 University of Ghana http://ugspace.ug.edu.gh Appendix 3: Distribution chart of the palynomorphs recovered from Dzata-2A well. 306 University of Ghana http://ugspace.ug.edu.gh Continued. 307 University of Ghana http://ugspace.ug.edu.gh Continued. 308 University of Ghana http://ugspace.ug.edu.gh Continued. 309 University of Ghana http://ugspace.ug.edu.gh Appendix 4: Relative abundance (%) of POM and palynomorphs in Lynx-1X well Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 2520 36 29 6 2 5 19 3 2540 35 25 4 2 6 24 4 2560 34 26 6 1 5 25 3 2580 28 30 4 1 8 25 4 2600 35 33 3 1 4 22 2 2620 30 30 1 2 9 26 2 2640 23 23 6 1 9 33 5 2660 22 28 8 2 6 27 7 2680 20 32 8 1 6 23 10 2700 20 28 10 2 8 23 9 2720 23 29 20 1 8 8 11 2740 19 21 28 2 8 9 13 2760 27 21 28 1 7 5 11 2780 20 26 23 2 9 6 14 2800 23 20 22 3 10 8 14 2820 38 12 26 3 8 7 6 2840 41 10 24 2 8 8 7 2860 45 11 26 2 6 6 4 2880 42 12 22 1 10 7 6 2900 64 10 12 1 5 4 4 2920 58 6 8 1 8 11 8 2940 60 18 4 1 4 9 4 2960 52 8 16 1 8 9 6 2980 54 10 8 1 9 10 8 3000 54 9 12 0 5 13 7 3020 52 12 15 1 5 11 4 3040 55 14 12 1 5 8 5 3060 58 15 7 1 5 9 5 3080 52 18 6 0 6 12 6 3100 57 9 4 2 11 10 7 3120 52 7 7 2 12 14 6 3140 47 10 6 1 10 18 8 3160 58 12 4 2 10 10 4 3180 50 10 5 2 10 18 5 3200 51 7 8 2 8 19 5 310 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3220 53 12 6 2 7 15 5 3240 61 11 5 1 6 13 3 3260 60 13 6 1 7 10 3 3280 62 8 4 1 5 14 6 3300 60 8 8 1 5 13 5 3320 73 19 3 1 4 0 0 3340 72 24 4 0 0 0 0 3360 66 23 7 0 3 0 0 3380 77 20 3 0 0 0 0 3400 73 21 4 1 1 0 0 3420 72 21 7 0 0 0 0 3440 73 20 6 0 1 0 0 3460 66 26 6 0 1 0 0 3480 69 24 5 1 1 0 0 3500 70 22 8 0 0 0 0 3520 70 24 6 0 0 0 0 3540 72 11 16 0 1 0 0 3560 72 13 15 0 0 0 0 3580 64 16 19 0 1 0 0 3600 66 18 13 0 3 0 0 3620 70 17 12 0 1 0 0 3640 67 15 18 0 0 0 0 3656-3660 72 23 5 0 0 0 0 3670-3680 76 20 4 0 0 0 0 3690-3700 75 20 5 0 0 0 0 3710-3720 70 25 5 0 0 0 0 3730-3740 66 29 5 0 0 0 0 3750-3760 67 30 2 0 1 0 0 3770-3780 73 23 4 0 0 0 0 3790-3800 71 20 9 0 0 0 0 3815-3820 74 19 6 0 1 0 0 3835-3840 71 21 7 1 0 0 0 3855-3860 75 22 3 0 0 0 0 3875-3880 48 42 10 0 0 0 0 3895-3900 48 35 14 0 3 0 0 3915-3920 46 44 7 0 3 0 0 311 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3935-3940 41 48 10 0 1 0 0 3955-3960 50 50 0 0 0 0 0 3975-3980 43 56 1 0 0 0 0 3995-4000 40 46 11 0 3 0 0 4015-4020 40 49 8 0 2 0 0 4035-4040 48 44 7 0 1 0 0 4055-4060 22 73 5 0 0 0 0 4075-4080 23 73 3 0 1 0 0 4095-4100 22 70 8 0 0 0 0 4115-4120 25 74 1 0 0 0 0 4135-4140 27 71 2 0 0 0 0 4155-4160 22 76 2 0 0 0 0 4175-4180 22 75 3 0 0 0 0 4195-4200 14 75 10 0 1 0 0 4215-4220 13 79 6 0 2 0 0 4235-4240 18 70 9 0 3 0 0 4255-4260 17 75 7 0 1 0 0 4275-4280 14 80 6 0 0 0 0 4295-4300 11 81 7 0 1 0 0 4315-4320 10 80 8 0 2 0 0 4355-4360 15 83 2 0 0 0 0 4375-4380 12 81 7 0 0 0 0 4395-4400 16 82 1 0 1 0 0 4415-4420 13 79 3 1 4 0 0 4435-4440 10 84 2 1 3 0 0 4455-4460 10 80 3 0 7 0 0 4475-4480 10 86 3 0 1 0 0 4495-4500 11 82 7 0 0 0 0 4515-4520 14 84 2 0 0 0 0 4540 14 85 1 0 0 0 0 4580 40 50 8 0 2 0 0 4595-4600 44 53 3 0 0 0 0 4615-4620 45 48 6 0 1 0 0 4635-4640 51 40 7 0 2 0 0 4655-4660 10 83 7 0 0 0 0 4675-4680 14 80 5 0 1 0 0 312 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 4695-4700 10 78 6 0 6 0 0 4715-4720 9 79 4 1 7 0 0 4735-4740 42 48 9 0 1 0 0 4755-4760 43 47 7 0 3 0 0 4775-4780 40 42 15 0 3 0 0 4795-4800 43 51 5 0 1 0 0 4815-4820 44 50 6 0 0 0 0 4835-4840 42 47 10 0 1 0 0 4895-4900 58 28 12 0 2 0 0 4915-5920 53 31 10 1 5 0 0 4955-4960 50 35 12 1 2 0 0 4995-5000 48 42 9 0 1 0 0 5035-5040 9 90 1 0 0 0 0 5075-5080 11 80 9 0 0 0 0 5095-5100 18 78 4 0 0 0 0 5135-5140 20 71 7 0 2 0 0 5155-5160 13 80 4 0 3 0 0 5215-5220 18 80 2 0 0 0 0 5235-5240 12 84 3 0 1 0 0 5275-5280 10 87 1 0 2 0 0 5295-5300 10 85 5 0 0 0 0 313 University of Ghana http://ugspace.ug.edu.gh Appendix 5: Relative abundance (%) of POM and palynomorphs in Dzata-1 well Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 2450 60 8 12 1 1 16 2 2470 67 4 7 2 2 15 3 2490 57 10 10 1 2 16 3 2510 60 8 8 1 3 16 4 2530 61 10 9 0 2 16 1 2550 60 6 12 1 2 17 2 2570 66 5 6 1 2 18 2 2590 60 4 8 0 4 21 3 2610 62 3 5 0 4 24 2 2630 70 2 4 1 2 20 2 2650 68 3 4 0 2 21 2 2670 70 5 6 1 2 15 1 2690 71 3 5 0 2 17 1 2710 68 4 8 1 2 16 1 2730 70 5 6 1 2 15 1 2750 80 2 6 1 1 9 1 2770 82 3 5 0 2 12 2 2790 77 2 3 1 1 15 1 2810 74 4 5 1 2 13 1 2830 76 3 6 2 1 11 1 2850 79 2 6 1 1 9 2 2870 81 3 5 0 1 7 2 2890 78 2 8 1 2 8 1 2910 80 1 4 1 1 13 1 2930 75 4 3 1 1 14 2 2950 74 6 5 0 2 11 2 2970 77 7 6 1 1 8 1 2990 73 5 8 1 2 8 2 3010 76 3 5 1 1 11 3 3030 34 40 17 1 8 0 0 3050 30 45 15 1 9 0 0 3070 40 42 12 0 5 0 0 3090 23 52 18 0 7 0 0 3110 32 44 15 0 8 0 0 3130 40 46 8 1 5 0 1 314 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3150 30 54 9 0 6 0 0 3170 65 13 9 6 7 0 0 3190 71 11 6 4 8 0 0 3210 76 8 5 4 7 0 0 3230 32 30 24 3 11 0 0 3250 22 36 18 4 20 0 0 3270 20 32 20 5 23 0 0 3290 21 30 20 6 23 0 0 3310 20 26 21 6 27 0 0 3330 19 29 25 3 24 0 0 3350 20 32 24 3 20 1 0 3370 30 21 22 3 23 0 0 3390 30 22 28 2 17 0 0 3410 28 23 28 3 18 0 0 3430 27 20 29 3 20 1 0 3450 25 22 30 3 20 0 0 3470 23 23 34 4 16 0 0 3490 22 30 36 2 10 0 0 3510 23 20 35 4 18 0 0 3530 26 13 37 4 19 1 0 3550 29 15 35 4 17 0 0 3570 21 28 32 2 17 0 0 3590 19 31 30 3 17 0 0 3610 27 37 18 2 16 0 0 3630 24 40 18 2 16 0 0 3650 10 80 5 0 4 0 0 3670 3 94 1 0 2 0 0 3690 8 90 0 0 2 0 0 3710 20 23 35 2 20 0 0 3730 21 23 33 4 19 0 0 3750 22 28 30 3 17 0 0 3770 35 30 22 2 11 0 0 3790 25 30 30 2 13 0 0 3810 21 38 21 2 18 0 0 3830 18 35 31 3 13 0 0 3850 30 30 24 2 14 0 0 315 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3870 22 22 36 3 17 0 0 3890 25 25 30 3 17 0 0 3910 22 40 22 4 12 0 0 3930 25 30 25 5 15 0 0 3950 19 28 27 3 23 0 0 3970 18 30 30 3 19 0 0 3990 25 34 22 2 17 0 0 4010 20 35 25 3 17 0 0 4030 54 28 15 1 2 0 0 4230 51 33 10 2 4 0 0 4270 56 38 3 0 3 0 0 4370 55 36 4 1 4 0 0 4390 50 30 10 2 8 0 0 316 University of Ghana http://ugspace.ug.edu.gh Appendix 6: Relative abundance (%) of POM and palynomorphs in Dzata-2A well Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 2420 70 4 10 1 2 10 3 2440 70 3 9 1 2 14 1 2460 66 4 9 0 2 15 4 2480 65 5 7 0 3 19 1 2500 66 4 8 0 3 18 1 2520 70 6 7 0 2 14 1 2540 69 5 9 0 2 12 3 2560 66 3 7 0 3 19 2 2580 68 3 5 1 3 16 5 2600 74 8 10 0 2 3 3 2620 73 10 9 0 1 5 2 2640 78 6 10 0 1 5 0 2660 72 5 19 0 1 3 0 2682 83 3 11 0 0 3 0 2700 86 3 9 0 0 2 0 2721 88 2 7 0 0 2 0 2742 86 5 6 0 1 2 0 2760 83 4 9 0 1 3 0 2781 86 4 6 0 1 2 0 2802 85 4 6 0 1 4 0 2820 78 10 8 0 1 3 0 2841 76 10 9 0 1 3 0 2862 81 9 5 0 1 3 1 2880 82 5 8 0 2 3 0 2901 89 3 5 0 3 0 0 2922 88 2 6 0 4 0 0 2943 85 4 6 0 5 0 0 2964 57 5 20 3 14 1 0 2982 59 7 14 2 18 0 0 3000 58 9 15 3 15 0 0 3021 60 7 15 2 16 0 0 3042 55 8 18 2 17 0 0 3063 58 9 19 2 11 1 0 3084 53 10 20 2 15 0 0 3105 81 5 5 1 8 0 0 317 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3126 77 6 9 1 7 0 0 3147 79 8 6 1 6 0 0 3168 40 30 20 1 9 0 0 3189 37 30 22 1 9 0 0 3210 39 37 20 0 4 0 0 3231 40 34 21 0 5 0 0 3252 34 33 26 0 7 0 0 3273 35 35 22 1 7 0 0 3294 33 28 24 4 11 0 0 3312 30 32 31 0 7 0 0 3333 46 25 23 0 6 0 0 3354 38 34 19 2 8 0 0 3375 40 30 20 1 8 1 0 3396 53 9 10 4 23 1 0 3412 56 6 9 3 26 0 0 3430 64 5 8 2 21 0 0 3450 62 7 9 1 19 1 0 3470 64 8 7 0 21 0 0 3490 63 7 8 5 17 0 0 3510 59 9 9 0 22 1 0 3530 60 8 6 2 23 1 0 3550 61 23 7 0 9 0 0 3570 65 22 8 0 5 0 0 3590 62 21 9 0 8 0 0 3610 65 22 6 0 6 0 0 3630 67 23 5 0 5 0 0 3650 32 19 22 1 26 0 0 3670 25 20 24 1 30 0 0 3690 30 16 29 0 25 0 0 3710 35 18 20 3 24 0 0 3730 29 20 23 3 25 0 0 3750 35 17 23 2 21 3 0 3770 34 19 20 0 25 2 0 3790 31 19 20 3 25 1 1 3810 30 18 27 0 24 1 0 3830 30 14 29 3 23 1 0 318 University of Ghana http://ugspace.ug.edu.gh Continued. Depth/m AOM (%) Opaques (%) Phytoclasts (%) Spores (%) Pollen (%) Gonyaulacoids (%) Peridinoids (%) 3850 40 22 20 0 16 2 0 3870 40 20 24 2 12 1 1 3890 32 19 28 2 17 0 2 3910 35 20 30 3 12 0 0 3930 60 24 12 0 4 0 0 3950 60 28 7 0 5 0 0 3970 55 29 10 0 4 2 0 3990 65 25 7 0 2 1 0 4010 68 23 8 0 1 0 0 4050 62 21 15 0 2 0 0 4090 50 33 14 0 2 1 0 4130 50 37 12 0 1 0 0 4150 58 32 10 0 0 0 0 4297 60 30 10 0 0 0 0 4363 58 32 10 0 0 0 0 4426 60 30 10 0 0 0 0 319 University of Ghana http://ugspace.ug.edu.gh Appendix 7: Rock-Eval pyrolysis data of rocks of the Albian-Eocene of Lynx-1X well Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax(⸰C) HI OI S2/S3 S1/TOC *100 PI S1+S2(mg/g) (Rcalculated %) Early Eocene 2525 0.99 0.11 3.22 0.62 426 326 63 5.18 11.13 0.03 3.33 0.51 Early Eocene 2545 0.53 0.09 0.42 0.43 422 78 81 0.97 16.85 0.18 0.51 0.44 Early Eocene 2585 0.62 0.09 0.26 0.39 409 42 62 0.67 14.45 0.26 0.35 0.20 Paleocene 2645 0.6 0.11 0.25 0.59 418 42 99 0.43 18.3 0.3 0.36 0.36 Paleocene 2665 0.84 0.08 0.43 0.45 426 51 53 0.96 9.49 0.16 0.51 0.51 Paleocene 2685 0.9 0.13 0.41 0.44 423 46 49 0.93 14.46 0.24 0.54 0.45 Paleocene 2735 0.88 0.04 0.64 0.36 423 73 41 1.78 4.55 0.06 0.68 0.45 Maastrichtian 2755 1.63 0.08 3.82 0.39 428 234 24 9.8 4.9 0.02 3.9 0.54 Maastrichtian 2775 2.06 0.08 7.02 0.43 424 342 21 16.33 3.89 0.01 7.1 0.47 Maastrichtian 2805 1.56 0.14 3.07 0.38 431 197 24 8.11 8.97 0.04 3.21 0.60 Maastrichtian 2825 1.42 0.13 2.85 0.42 429 200 30 6.73 9.15 0.04 2.98 0.56 Maastrichtian 2845 1.71 0.16 4.91 0.52 426 286 30 9.41 9.33 0.03 5.07 0.51 Maastrichtian 2865 1.74 0.15 5.13 0.43 427 295 25 11.88 8.61 0.03 5.28 0.53 Maastrichtian 2885 2.37 0.16 9.02 0.63 423 380 27 14.31 6.74 0.02 9.18 0.45 Maastrichtian 2905 2.58 0.14 9.28 0.43 423 359 17 21.48 5.42 0.01 9.42 0.45 Maastrichtian 2925 2.25 0.14 7.68 0.41 425 341 18 18.97 6.22 0.02 7.82 0.49 Maastrichtian 2945 3.1 0.19 13 0.59 422 420 19 22.22 6.14 0.01 13.19 0.44 Maastrichtian 2965 2.3 0.18 9.88 0.4 422 429 17 24.94 7.81 0.02 10.06 0.44 Maastrichtian 2985 4.15 0.2 26.58 0.54 416 641 13 49.22 4.82 0.01 26.78 0.33 Maastrichtian 3005 2.89 0.21 18.4 0.51 418 638 18 35.86 7.28 0.01 18.61 0.36 Maastrichtian 3025 2.85 0.22 16.24 0.54 419 569 19 30.07 7.71 0.01 16.46 0.38 Maastrichtian 3045 2.06 0.17 9.77 0.47 421 474 23 20.89 8.24 0.02 9.94 0.42 Maastrichtian 3065 2 0.16 9.02 0.43 422 452 22 20.88 8.01 0.02 9.18 0.44 Maastrichtian 3085 1.83 0.15 6.84 0.49 425 373 27 14.07 8.18 0.02 6.99 0.49 Maastrichtian 3105 2.2 0.16 9.11 0.46 424 414 21 19.86 7.27 0.02 9.27 0.47 Campanian 3125 2.85 0.16 12.44 0.5 422 436 18 24.69 5.61 0.01 12.6 0.44 Campanian 3145 3.29 0.16 16.32 0.5 423 495 15 32.38 4.86 0.01 16.48 0.45 Campanian 3165 1.43 0.13 4.53 0.45 427 317 32 10.06 9.1 0.03 4.66 0.53 Campanian 3185 1.92 0.13 9.44 0.48 420 491 25 19.78 6.76 0.01 9.57 0.40 Campanian 3205 2.13 0.14 8.82 0.74 422 414 35 11.92 6.58 0.02 8.96 0.44 Campanian 3225 1.23 0.13 4.78 0.42 421 387 34 11.37 10.53 0.03 4.91 0.42 Campanian 3245 1.19 0.12 2.54 0.4 427 213 34 6.35 10.08 0.05 2.66 0.53 Campanian 3265 2.24 0.14 7.87 0.51 425 352 23 15.43 6.26 0.02 8.01 0.49 Campanian 3285 2.51 0.12 11.52 0.46 424 460 18 25.05 4.79 0.01 11.64 0.47 Campanian 3305 2.25 0.16 11.51 0.57 425 511 25 20.19 7.11 0.01 11.67 0.49 320 University of Ghana http://ugspace.ug.edu.gh Continued. Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax(⸰C) HI OI S2/S3 S1/TOC *100 PI S1+S2(mg/g) (Rcalculated %) ?Turonian- 3325 1.79 0.12 5.18 0.41 427 290 23 12.63 6.71 0.02 5.3 0.53 Santonian ?Turonian- 3345 1.5 0.11 4.67 0.45 430 312 30 10.38 7.34 0.02 4.78 0.58 Santonian ?Turonian- 3365 1.64 0.14 5.57 0.61 428 340 37 9.14 8.54 0.02 5.71 0.54 Santonian ?Turonian- 3385 1.58 0.16 6.38 0.53 427 405 34 12.04 10.15 0.02 6.54 0.53 Santonian ?Turonian- 3405 2.06 0.16 10.91 0.5 426 530 24 21.83 7.77 0.01 11.07 0.51 Santonian ?Turonian- 3425 2.06 0.17 12.58 0.68 427 609 33 18.5 8.24 0.01 12.75 0.53 Santonian ?Turonian- 3445 2.35 0.17 13.32 0.41 426 568 17 32.49 7.25 0.01 13.49 0.51 Santonian ?Turonian- 3465 2.22 0.15 12.79 0.37 427 577 17 34.58 6.76 0.01 12.94 0.53 Santonian ?Turonian- 3485 1.7 0.15 7.81 0.45 428 460 27 17.36 8.83 0.02 7.96 0.54 Santonian ?Turonian- 3505 1.67 0.16 7.39 0.44 428 442 26 16.79 9.56 0.02 7.55 0.54 Santonian ?Turonian- 3525 1.92 0.14 10.76 0.4 428 560 21 26.91 7.29 0.01 10.9 0.54 Santonian ?Turonian- 3545 1.95 0.13 10.16 0.38 429 521 19 26.74 6.67 0.01 10.29 0.56 Santonian ?Turonian- 3565 1.8 0.15 9.33 0.44 430 519 24 21.21 8.33 0.02 9.48 0.58 Santonian ?Turonian- 3585 1.98 0.15 10.4 0.42 430 526 21 24.75 7.59 0.01 10.55 0.58 Santonian ?Turonian- 3605 2.11 0.14 12.5 0.51 430 593 24 24.51 6.64 0.01 12.64 0.58 Santonian ?Turonian- 3615 1.86 0.08 9.63 0.34 432 517 18 28.32 4.3 0.01 9.71 0.62 Santonian ?Turonian- 3625 2.12 0.16 10.41 0.37 430 492 17 28.12 7.57 0.02 10.57 0.58 Santonian ?Turonian- 3635 1.84 0.11 8.83 0.27 432 480 15 32.7 5.98 0.01 8.94 0.62 Santonian ?Turonian- 3658 2.52 0.18 11.11 0.79 432 441 31 14.06 7.15 0.02 11.29 0.62 Santonian ?Turonian- 3675 2.56 0.17 14.81 0.53 431 579 21 27.94 6.64 0.01 14.98 0.60 Santonian ?Turonian- 3695 3.08 0.17 18.93 0.42 431 614 14 45.07 5.51 0.01 19.1 0.60 Santonian Cenomanian 3715 1.43 0.17 6.52 0.44 432 456 31 14.82 11.89 0.03 6.69 0.62 Cenomanian 3735 0.97 0.08 3.47 0.25 431 359 26 13.88 8.27 0.02 3.55 0.60 Cenomanian 3755 0.97 0.07 3.68 0.23 431 378 24 16 7.19 0.02 3.75 0.60 Cenomanian 3775 1.23 0.07 4.65 0.27 434 377 22 17.22 5.68 0.01 4.72 0.65 Cenomanian 3795 1.18 0.08 4.98 0.26 434 422 22 19.15 6.79 0.02 5.06 0.65 Cenomanian 3817.5 1.69 0.06 7.52 0.27 434 445 16 27.85 3.55 0.01 7.58 0.65 Cenomanian 3837.5 1.68 0.1 7.92 0.39 435 471 23 20.31 5.95 0.01 8.02 0.67 Cenomanian 3857.5 2.04 0.08 8.4 0.42 437 412 21 20 3.92 0.01 8.48 0.71 Cenomanian 3877.5 1.75 0.09 5.25 0.49 437 300 28 10.71 5.14 0.02 5.34 0.71 Cenomanian 3897.5 1.24 0.07 2.33 0.19 440 188 15 12.26 5.65 0.03 2.4 0.76 Cenomanian 3917.5 0.87 0.05 1.32 0.28 438 151 32 4.71 5.72 0.04 1.37 0.72 Cenomanian 3937 0.91 0.01 1.36 0.18 445 149 20 7.56 1.09 0.01 1.37 0.85 Cenomanian 3977.5 0.51 0.12 0.25 0.25 425 49 49 1 23.53 0.32 0.37 0.49 Cenomanian 3997.5 0.54 0.06 0.47 0.18 437 87 33 2.61 11.05 0.11 0.53 0.71 Cenomanian 4017.5 0.86 0.1 1.31 0.17 440 153 20 7.71 11.66 0.07 1.41 0.76 Cenomanian 4037.5 0.75 0.07 0.81 0.3 438 107 40 2.7 9.28 0.08 0.88 0.72 Cenomanian 4057.5 0.54 0.06 0.92 0.23 438 171 43 4 11.15 0.06 0.98 0.72 Cenomanian 4077.5 0.52 0.07 0.37 0.46 430 71 88 0.8 13.44 0.16 0.44 0.58 Cenomanian 4098 1.1 0.73 2.57 0.11 445 233 10 23.36 66.24 0.22 3.3 0.85 321 University of Ghana http://ugspace.ug.edu.gh Continued. Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax(⸰C) HI OI S2/S3 S1/TOC *100 PI S1+S2(mg/g) (Rcalculated %) Cenomanian 4157.5 0.73 0.1 0.46 0.21 423 63 29 2.19 13.66 0.18 0.56 0.45 Cenomanian 4177.5 0.99 0.05 0.2 0.78 430 20 78 0.26 5.03 0.2 0.25 0.58 Cenomanian 4217.5 0.86 0.05 0.76 0.19 443 88 22 4 5.82 0.06 0.81 0.81 Cenomanian 4237.5 1.11 0.07 1.71 0.5 443 154 45 3.42 6.3 0.04 1.78 0.81 Cenomanian 4257 1.99 3.22 5.02 0.21 446 252 11 23.9 161.73 0.39 8.24 0.87 Cenomanian 4277.5 1.24 0.09 0.68 0.33 433 55 27 2.06 7.26 0.12 0.77 0.63 Cenomanian 4296 2.71 7.98 7.25 0.25 449 268 9 29 294.9 0.52 15.23 0.92 Cenomanian 4317.5 0.8 0.1 1.31 0.49 444 163 61 2.67 12.44 0.07 1.41 0.83 Cenomanian 4332.5 0.69 0.04 0.68 0.35 452 99 51 1.94 5.8 0.06 0.72 0.98 Cenomanian 4377.5 1.06 0.07 0.73 0.52 452 69 49 1.4 6.58 0.09 0.8 0.98 Cenomanian 4397.5 0.94 0.07 0.63 0.47 456 67 50 1.34 7.47 0.1 0.7 1.05 Cenomanian 4417.5 0.67 0.08 0.57 0.44 456 85 66 1.3 11.99 0.12 0.65 1.05 Cenomanian 4437.5 0.82 0.07 0.69 0.36 458 84 44 1.92 8.56 0.09 0.76 1.08 Cenomanian 4457.5 1.76 0.07 1.68 0.4 456 95 23 4.2 3.97 0.04 1.75 1.05 Cenomanian 4477.5 1.57 0.07 1.59 0.43 456 101 27 3.7 4.46 0.04 1.66 1.05 Cenomanian 4517.5 6.48 0.11 8.68 0.6 461 134 9 14.47 1.7 0.01 8.79 1.14 Albian 4537.5 0.72 0.08 0.96 0.56 454 134 78 1.71 11.17 0.08 1.04 1.01 Albian 4597.5 0.89 0.06 0.84 0.37 459 94 41 2.27 6.72 0.07 0.9 1.10 Albian 4612.5 0.81 0.02 0.53 0.08 461 66 10 6.31 2.47 0.04 0.55 1.14 Albian 4637.5 0.5 0.06 0.48 0.29 451 97 58 1.66 12.07 0.11 0.54 0.96 Albian 4657.5 0.52 0.19 0.52 0.29 455 100 56 1.79 36.61 0.27 0.71 1.03 Albian 4717.5 0.66 0.04 0.32 0.29 476 48 44 1.1 6.06 0.11 0.36 1.41 Albian 4737.5 0.85 0.17 0.67 0.49 465 79 58 1.37 20.09 0.2 0.84 1.21 Albian 4757.5 0.8 0.14 0.68 0.48 455 85 60 1.42 17.54 0.17 0.82 1.03 Albian 4777.5 1.13 0.24 1.25 0.45 453 111 40 2.78 21.33 0.16 1.49 0.99 Albian 4797.5 0.71 0.17 0.52 0.48 446 73 67 1.08 23.81 0.25 0.69 0.87 Albian 4817.5 0.53 0.16 0.45 0.4 447 85 76 1.13 30.3 0.26 0.61 0.89 Albian 4837.5 0.83 0.13 0.51 0.49 453 62 59 1.04 15.76 0.2 0.64 0.99 Albian 4862.5 0.55 0.04 0.31 0.39 442 57 71 0.79 7.31 0.11 0.35 0.80 Albian 4902.5 0.74 0.06 0.39 0.49 458 53 66 0.8 8.13 0.13 0.45 1.08 Albian 4922.5 0.58 0.06 0.56 0.36 431 96 62 1.56 10.27 0.1 0.62 0.60 Albian 4932.5 0.66 0.05 0.41 0.37 444 62 56 1.11 7.61 0.11 0.46 0.83 Albian 4955 0.49 0.01 0.24 0.11 426 49 23 2.18 2.05 0.04 0.25 0.51 Albian 4997.5 0.65 0.04 0.32 0.25 424 50 39 1.28 6.19 0.11 0.36 0.47 Albian 5067.5 0.67 0.05 0.39 0.37 430 58 55 1.05 7.47 0.11 0.44 0.58 Albian 5077.5 0.6 0.04 0.35 0.28 417 58 47 1.25 6.68 0.1 0.39 0.35 322 University of Ghana http://ugspace.ug.edu.gh Continued. Age Depth/ %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax(⸰C) HI OI S2/S3 S1/TOC *100 PI S1+S2(mg/g) (Rcalculated %) m Albian 5097.5 0.62 0.04 0.31 0.25 428 50 40 1.24 6.47 0.11 0.35 0.54 Albian 5137.5 0.62 0.04 0.21 0.31 424 34 50 0.68 6.44 0.16 0.25 0.47 Albian 5157.5 0.73 0.04 0.27 0.25 417 37 34 1.08 5.51 0.13 0.31 0.35 Albian 5207.5 0.51 0.06 0.72 0.49 437 140 96 1.47 11.7 0.08 0.78 0.71 Albian 5227.5 0.64 0.04 0.39 0.36 428 61 56 1.08 6.24 0.09 0.43 0.54 Albian 5237.5 0.57 0.05 0.42 0.34 430 74 60 1.24 8.83 0.11 0.47 0.58 Albian 5277.5 0.83 0.05 0.43 0.45 429 52 54 0.96 6.02 0.1 0.48 0.56 Albian 5297.5 0.99 0.08 0.49 0.57 426 50 58 0.86 8.09 0.14 0.57 0.51 323 University of Ghana http://ugspace.ug.edu.gh Appendix 8: Rock-Eval pyrolysis data of rocks of the Albian-Maastrichtian of Dzata-2A well Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax (°C) HI OI S2/S3 S1/TOC*100 PI S1+S2(mg/g) Rcalculated Maastrichtian 2418-2420 6.1 0.29 27.37 2.4 419 449 39 11.4 5 0.01 27.66 0.38 Maastrichtian 2430-2440 3.62 0.23 12.04 1.56 426 333 43 7.7 6 0.02 12.27 0.51 Maastrichtian 2450-2460 1.96 0.14 4.13 0.66 427 211 34 6.3 7 0.03 4.27 0.53 Maastrichtian 2470-2480 1.67 0.13 4.53 0.44 423 271 26 10.3 8 0.03 4.66 0.45 Maastrichtian 2500-2510 2.37 0.12 5.22 0.51 423 220 21 10.2 5 0.02 5.34 0.45 Maastrichtian 2520-2530 2.88 0.12 7.74 0.65 423 269 23 11.9 4 0.02 7.86 0.45 Maastrichtian 2540-2550 2.45 0.13 5.32 0.81 424 217 33 6.6 5 0.02 5.45 0.47 Maastrichtian 2560-2570 2.91 0.13 8.62 0.44 421 296 15 19.6 4 0.01 8.75 0.42 Maastrichtian 2580-2590 2.3 0.12 5.98 0.82 424 260 36 7.3 5 0.02 6.1 0.47 Maastrichtian 2600-2610 2.19 0.11 4.87 0.48 422 222 22 10.1 5 0.02 4.98 0.44 Maastrichtian 2620-2630 2.14 0.1 4.79 0.73 427 224 34 6.6 5 0.02 4.89 0.53 Campanian 2630-2640 1.77 0.12 3.33 0.4 423 188 23 8.3 7 0.03 3.45 0.45 Campanian 2650-2660 2.27 0.13 5.07 0.89 419 223 39 5.7 6 0.02 5.2 0.38 Campanian 2673-2676 4.27 0.15 22.27 1.26 416 521 29 17.7 4 0.01 22.42 0.33 Campanian 2682-2685 3.11 0.11 12.42 0.95 418 399 31 13.1 4 0.01 12.53 0.36 Campanian 2700-2703 2.78 0.1 8.42 0.7 420 302 25 12 4 0.01 8.52 0.40 Campanian 2721-2724 2.73 0.09 10.07 0.67 414 368 25 15 3 0.01 10.16 0.29 Campanian 2742-2745 2.34 0.09 8.29 0.72 417 354 31 11.5 4 0.01 8.38 0.35 Campanian 2760-2763 2.94 0.13 9.23 0.78 420 314 27 11.8 4 0.01 9.36 0.40 Campanian 2781-2784 2.77 0.09 10.87 0.54 418 392 19 20.1 3 0.01 10.96 0.36 ?Turonian- 2799-2802 1.97 0.09 7.94 0.41 421 403 21 19.4 5 0.01 8.03 0.42 Santonian ?Turonian- 2820-2823 2.35 0.1 9.64 0.45 421 410 19 21.4 4 0.01 9.74 0.42 Santonian ?Turonian- 2838-2841 2.29 0.09 8.16 0.53 421 357 23 15.4 4 0.01 8.25 0.42 Santonian ?Turonian- 2862-2865 2.56 0.08 9.94 0.41 419 388 16 24.2 3 0.01 10.02 0.38 Santonian ?Turonian- 2880-2883 2.59 0.08 10.62 0.43 417 410 17 24.7 3 0.01 10.7 0.35 Santonian ?Turonian- 2901-2904 2.83 0.09 14.72 0.41 417 520 14 35.9 3 0.01 14.81 0.35 Santonian ?Turonian- 2919-2922 4.02 0.18 21.28 0.72 417 530 18 29.6 4 0.01 21.46 0.35 Santonian Cenomanian 2940-2943 1.75 0.14 4.48 0.45 421 256 26 10 8 0.03 4.62 0.42 Cenomanian 2961-2964 1.47 0.14 1.54 0.52 424 105 35 3 10 0.08 1.68 0.47 Cenomanian 2979-2982 1.16 0.15 1.39 0.47 426 119 40 3 13 0.1 1.54 0.51 Cenomanian 3000-3003 1.2 0.14 1.21 0.45 427 101 37 2.7 12 0.1 1.35 0.53 Cenomanian 3021-3024 1.36 0.15 1.45 0.51 425 107 38 2.8 11 0.09 1.6 0.49 Cenomanian 3042-3045 1.67 0.18 2.08 0.49 426 124 29 4.2 11 0.08 2.26 0.51 Cenomanian 3066-3069 1.58 0.22 2.25 0.57 425 142 36 3.9 14 0.09 2.47 0.49 Cenomanian 3081-3084 1.44 0.22 1.5 0.55 425 104 38 2.7 15 0.13 1.72 0.49 Cenomanian 3105-3108 1.32 0.17 1.49 0.36 425 113 27 4.1 13 0.1 1.66 0.49 Cenomanian 3123-3126 1.41 0.15 1.4 0.47 426 99 33 3 11 0.1 1.55 0.51 324 University of Ghana http://ugspace.ug.edu.gh Continued. Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax (°C) HI OI S2/S3 S1/TOC*10 PI S1+S2(mg/g) Rcalculated 0 Cenomanian 3147-3150 1.56 0.13 1.18 0.5 427 76 32 2.4 8 0.1 1.31 0.53 Cenomanian 3165-3168 1.4 0.15 0.86 0.47 428 61 33 1.8 11 0.15 1.01 0.54 Cenomanian 3189-3192 0.87 0.15 0.5 0.59 425 58 68 0.8 17 0.23 0.65 0.49 Cenomanian 3210-3213 0.66 0.08 0.39 0.46 430 59 70 0.8 12 0.17 0.47 0.58 Cenomanian 3231-3234 0.51 0.08 0.24 0.47 433 47 92 0.5 16 0.25 0.32 0.63 Cenomanian 3252-3255 0.68 0.08 0.31 0.8 428 46 118 0.4 12 0.21 0.39 0.54 Cenomanian 3273-3276 0.55 0.07 0.29 0.37 425 53 68 0.8 13 0.19 0.36 0.49 Cenomanian 3294-3297 0.81 0.08 0.48 0.62 434 59 77 0.8 10 0.14 0.56 0.65 Cenomanian 3312-3315 1 0.07 0.65 0.47 432 65 47 1.4 7 0.1 0.72 0.62 Cenomanian 3333-3336 1.35 0.08 0.96 0.55 433 71 41 1.7 6 0.08 1.04 0.63 Cenomanian 3351-3354 1.23 0.07 1.03 0.5 428 84 41 2.1 6 0.06 1.1 0.54 Albian 3375-3378 1.04 0.09 0.86 0.69 431 83 66 1.2 9 0.09 0.95 0.60 Albian 3396-3399 1.21 0.08 1.36 0.44 434 112 36 3.1 7 0.06 1.44 0.65 Albian 3412-3420 1.46 0.08 1.41 0.65 434 96 44 2.2 5 0.05 1.49 0.65 Albian 3430-3440 1.2 0.1 1.01 0.47 429 84 39 2.1 8 0.09 1.11 0.56 Albian 3450-3460 1.71 0.09 1.41 0.61 433 82 36 2.3 5 0.06 1.5 0.63 Albian 3470-3480 1.74 0.08 1.67 0.57 431 96 33 2.9 5 0.05 1.75 0.60 Albian 3490-3500 1.86 0.09 2.24 0.56 432 120 30 4 5 0.04 2.33 0.62 Albian 3510-3520 1.64 0.09 1.39 0.53 432 85 32 2.6 5 0.06 1.48 0.62 Albian 3530-3540 0.83 0.06 0.54 0.73 434 65 88 0.7 7 0.1 0.6 0.65 Albian 3550-3560 1.42 0.07 1.15 0.43 433 81 30 2.7 5 0.06 1.22 0.63 Albian 3570-3580 1.2 0.08 0.52 0.65 436 43 54 0.8 7 0.13 0.6 0.69 Albian 3590-3600 1.07 0.06 0.8 0.56 438 75 52 1.4 6 0.07 0.86 0.72 Albian 3610-3620 0.97 0.07 0.67 0.53 434 69 55 1.3 7 0.09 0.74 0.65 Albian 3630-3640 0.93 0.07 0.52 0.52 434 56 56 1 8 0.12 0.59 0.65 Albian 3650-3660 0.96 0.07 0.74 0.47 434 77 49 1.6 7 0.09 0.81 0.65 Albian 3670-3680 1.14 0.07 0.95 0.5 436 84 44 1.9 6 0.07 1.02 0.69 Albian 3690-3700 1.08 0.06 0.84 0.45 438 78 42 1.9 6 0.07 0.9 0.72 Albian 3710-3720 1.42 0.08 1.52 0.55 437 107 39 2.8 6 0.05 1.6 0.71 Albian 3730-3740 1.45 0.08 1.32 0.49 436 91 34 2.7 6 0.06 1.4 0.69 Albian 3750-3760 1.22 0.08 1.28 0.51 436 105 42 2.5 7 0.06 1.36 0.69 Albian 3770-3780 1.64 0.09 1.93 0.45 437 118 27 4.3 5 0.04 2.02 0.71 Albian 3790-3800 1.6 0.09 1.64 0.47 437 102 29 3.5 6 0.05 1.73 0.71 Albian 3810-3820 1.23 0.08 0.82 0.46 434 67 37 1.8 7 0.09 0.9 0.65 Albian 3830-3840 1.31 0.09 0.91 0.45 435 69 34 2 7 0.09 1 0.67 Albian 3850-3860 0.9 0.07 0.72 0.56 435 80 62 1.3 8 0.09 0.79 0.67 Albian 3870-3880 0.97 0.07 0.6 0.58 440 62 60 1 7 0.1 0.67 0.76 Albian 3890-3900 0.88 0.07 0.57 0.59 439 65 67 1 8 0.11 0.64 0.74 Albian 3910-3920 1.36 0.07 1.14 0.53 442 84 39 2.2 5 0.06 1.21 0.80 Albian 3930-3940 1.19 0.08 1.13 0.53 443 95 44 2.1 7 0.07 1.21 0.81 Albian 3950-3960 1.1 0.07 0.78 0.51 442 71 47 1.5 6 0.08 0.85 0.80 Albian 3970-3980 1.23 0.07 1 0.45 440 81 37 2.2 6 0.07 1.07 0.76 325 University of Ghana http://ugspace.ug.edu.gh Continued. Age Depth/m %TOC S1(mg/g) S2(mg/g) S3(mg/g) Tmax (°C) HI OI S2/S3 S1/TOC*100 PI S1+S2(mg/g) Rcalculated Albian 3990-4000 1.61 0.07 1.04 0.48 440 65 30 2.2 4 0.06 1.11 0.76 Albian 4010-4020 1.38 0.07 1.14 0.47 440 83 34 2.4 5 0.06 1.21 0.76 Albian 4030-4040 1.45 0.07 0.89 0.45 439 62 31 2 5 0.07 0.96 0.74 Albian 4050-4060 0.73 0.06 0.34 0.51 446 47 70 0.7 8 0.15 0.4 0.87 Albian 4070-4080 1.33 0.08 0.63 0.61 446 47 46 1 6 0.11 0.71 0.87 Albian 4090-4100 0.98 0.08 0.86 0.42 440 88 43 2 8 0.09 0.94 0.76 Albian 4110-4120 1.22 0.08 0.96 0.4 444 79 33 2.4 7 0.08 1.04 0.83 Albian 4130-4140 1.18 0.07 0.67 0.27 449 57 23 2.5 6 0.09 0.74 0.92 Albian 4150-4160 1.17 0.09 0.67 0.28 449 58 24 2.4 8 0.12 0.76 0.92 Albian 4170-4180 1.19 0.07 0.75 0.28 444 63 24 2.7 6 0.09 0.82 0.83 Albian 4192-4195 1.21 0.08 0.62 0.27 443 51 22 2.3 7 0.11 0.7 0.81 Albian 4213-4216 1.74 0.11 1.02 0.32 442 59 18 3.2 6 0.1 1.13 0.80 Albian 4234-4237 0.79 0.06 0.27 0.29 434 34 37 0.9 8 0.18 0.33 0.65 Albian 4255-4258 0.69 0.06 0.25 0.34 440 36 49 0.7 9 0.19 0.31 0.76 Albian 4276-4279 0.59 0.05 0.21 0.31 441 35 52 0.7 8 0.19 0.26 0.78 Albian 4297-4300 1.28 0.06 0.44 0.4 448 34 31 1.1 5 0.12 0.5 0.90 Albian 4321-4324 0.58 0.05 0.25 0.32 442 43 55 0.8 9 0.17 0.3 0.80 Albian 4342-4345 1.03 0.06 0.37 0.55 443 36 54 0.7 6 0.14 0.43 0.81 Albian 4363-4366 1.54 0.07 0.55 0.69 435 36 45 0.8 5 0.11 0.62 0.67 Albian 4384-4387 1.54 0.08 0.56 0.66 441 36 43 0.8 5 0.13 0.64 0.78 Albian 4423-4426 1.56 0.08 0.53 0.57 442 34 37 0.9 5 0.13 0.61 0.80 Albian 4447-4450 0.82 0.07 0.35 0.59 436 43 72 0.6 9 0.17 0.42 0.69 326