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UNIVERSITY OF GHANA 
 
COLLEGE OF BASIC AND APPLIED SCIENCES 
 
 
 
GEOCHEMISTRY OF NEOPROTEROZOIC PHYLLITES FROM THE 
AKUAPIM RANGE, SOUTHEASTERN GHANA 
 
 
 
By 
BONSU SAMUEL 
(10278079) 
 
 
 
THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, 
LEGON IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE 
AWARD OF MPHIL GEOLOGY DEGREE  
 
JULY, 2015 
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DECLARATION 
This is to certify that this thesis is the result of research undertaken by Samuel Bonsu towards 
the award of Master of Philosophy in Geology in the Department of Earth Science, University 
of Ghana. 
 
 
……………………………………..                                  Date:……………………………….. 
BONSU SAMUEL 
(Student) 
 
 
……………………………………..                                  Date:……………………………….. 
PROF. D. K. ASIEDU 
(Principal Supervisor) 
 
 
……………………………………..                                  Date:……………………………….. 
DR. C. Y. ANANI 
(Co-Supervisor) 
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ABSTRACT 
Neoproterozoic phyllites from the Akuapim range, a prominent part of the Togo Structural 
Unit forms part of the Pan-African Dahoeyide orogen exposed at the southeastern part of 
Ghana. The area of study exhibit three varieties of phyllites which are carbonaceous, iron-
stained and micaceous phyllites. These phyllites have been analyzed for their mineralogical 
and geochemical characteristics to infer their source -area weathering, source rock composition 
and tectonic setting. The mineralogical content of ten (10) samples were determined using X-
ray diffraction method. Twenty-eight (28) samples were analyzed for their major, trace and 
rare earth element compositions using ICP-AES and ICP-MS. From the mineralogy, the 
phyllites are composed of quartz, feldspar, muscovite, chlorite, illite with some siderite, 
graphite and calcium carbonate. Compared to post-Archean Australian average Shale (PAAS), 
the phyllites are depleted in major elements with the exception of SiO2 and MnO which are 
enriched relative to PAAS. The phyllites show relative depletions in transition metals such as 
Sc, V and Cr whereas high field strength elements such as Zr, Hf, Y and Th are at an average 
to above-average concentrations as compared to PAAS. The phyllites show a single trend of 
LREE enrichment (average LaN/SmN = 3.78), nearly flat HREE and negative Eu anomaly 
(average Eu/Eu* = 0.61) similar to the trend of post-Archean Australian average shale. From 
geochemistry, the phyllites can be classified mostly as quartz-rich with few quartz-
intermediate. Al2O3 shows positive correlations with Sc, V, Cr, Rb, Sr, Cs, Ba and Y 
suggesting that these elements are primarily controlled by the dominant clay minerals. High 
values of K2O/Na2O (average = 54.31) and SiO2/Al2O3 (average = 8.17) of the phyllites 
indicates compositional maturity of the sediments. The phyllites reveal high concentrations of 
Zr (average = 408.08 ppm) which suggests sedimentary sorting. This is supported by the plot 
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of Th/Sc against Zr/Sc. High Chemical Index of Alteration (average = 74.73%), Plagioclase 
Index of Alteration (average = 87.68%), Chemical Index of Weathering (average = 98.36%), 
Rb/Sr (average = 4.22), Th/U (average = 4.09) values and low Index of Compositional 
Variability (average = 0.64) values of the analyzed samples indicate intense chemical 
weathering in the source areas. On the A-CN-K ternary diagram, data for the Neoproterozoic 
phyllites from the Akuapim range plot in a trend (along A-K line) indicating intense chemical 
weathering. The phyllites show geochemical characteristics typical of sediments derived from 
old Upper Continental Crust. Modeling of the average phyllites using the relatively immobile 
REEs and Th/Sc shows that the sediments are composed of a mixture of 80% Upper 
Continental Crust and 20% granite. The phyllites show mineralogical and geochemical 
characteristics indicative of sediments deposited within a passive continental margin and/or 
intra-cratonic terrane. The phyllites exhibit provenance characteristics similar to that of the 
Kwahu/Bombouaka Group of the Voltaian Basin and the Buem Structural Unit which are 
believed to be lateral equivalents and are probably derived from the same source in the 
Amazonian Craton. 
 
 
 
 
 
 
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DEDICATION 
This research work is dedicated to the Almighty God and to my parents Mr. and Mrs. Bonsu.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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ACKNOWLEDGEMENT 
My utmost gratitude goes to God who gave me strength, wisdom, knowledge and 
understanding to write this thesis. Glory and honour be unto His name. 
My profound gratitude goes to my supervisors, Prof. Daniel K. Asiedu and Dr. Chris Y. Anani 
for their excellent guidance, support and encouragement. I would also like to express my 
heartfelt gratitude to my parents Mr. and Mrs. Bonsu, my brother Eric Atta-Sonno and to my 
friend Wendy Annan. 
I acknowledge the financial support provided by the Department of Earth Science capacity 
Building Project, University of Ghana. 
Finally, to all my friends and colleagues I say thank you for your assistance and support. 
 
 
 
 
 
 
 
 
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TABLE OF CONTENTS 
DECLARATION….………………..……………………………..….………………………i 
ABSTRACT………………………………………………………….………........................ii 
DEDICATION…………………..…………………………………………….......................iv 
ACKNOWLEDGEMENT……….…………………………………………….......................v 
TABLE OF CONTENTS……….……………………………………………………..…......vi 
LIST OF FIGURES……………………………………………………..…………………....ix 
LIST OF TABLES………………………………………………….……..…………….......xiii 
CHAPTER ONE ......................................................................................................................1 
1.0 INTRODUCTION .............................................................................................................1 
1.1 BACKGROUND .............................................................................................................1 
1.2 OBJECTIVE ....................................................................................................................4 
    1.3 STUDY AREA .................................................................................................................4 
1.3.1 Location .....................................................................................................................4 
1.3.2 Accessibility ..............................................................................................................4 
1.3.3 Topography and Drainage .........................................................................................5 
1.3.4 Climate ......................................................................................................................5 
1.3.5 Vegetation and Soil ...................................................................................................5 
1.4 GEOLOGICAL SETTING ..............................................................................................6 
CHAPTER TWO .....................................................................................................................9 
2.0 LITERATURE REVIEW .................................................................................................9 
2.1 INTRODUCTION ...........................................................................................................9 
2.1.1 Provenance studies in fine-grained sedimentary rocks .............................................9 
2.1.2 Source rock composition of clastic sediments ........................................................10 
2.1.3 Chemical Weathering ..............................................................................................12 
2.1.4 Transportation of sediments ....................................................................................14 
           2.1.4.1 Abrasion and mechanical breakdown……………..………………………….14 
           2.1.4.2 Sorting and Mixing…...………………………………………………………15 
2.1.5 Diagenesis ...............................................................................................................16 
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2.2 DAHOMEYIDE BELT .................................................................................................17 
2.2.1 Dahomeyan Structural Unit .....................................................................................19 
2.2.2 Togo Structural Unit ................................................................................................20 
2.2.3 Buem Structural Unit...............................................................................................23 
     2.3 A GEOCHEMICAL APPROACH…………...........………………………………….23 
CHAPTER THREE ...............................................................................................................25 
3.0 MATERIALS AND METHODS ........................................................................................ 
3.1 DESK STUDY AND FIELD WORK ............................................................................26 
3.1.1 Desk Study ..............................................................................................................26 
3.1.2 Field Work ...............................................................................................................27 
3.2 LABORATORY WORK ...............................................................................................28 
3.2.1 Sample preparation ..................................................................................................28 
3.2.2 Mineralogical analysis .............................................................................................29 
3.2.3 Geochemical analysis ..............................................................................................30 
3.2.4 Data analyses ...........................................................................................................31 
CHAPTER FOUR .................................................................................................................32 
4.0 RESULTS .........................................................................................................................32 
4.1 PETROGRAPHY ..........................................................................................................32 
4.1.1 Field Observations ...................................................................................................32 
           4.1.1.1 Carbonaceous (dark-grey) Phyllites………………...………………………32 
           4.1.1.2 Iron-stained (reddish) Phyllites……………….…………………………….33 
           4.1.1.3 Micaceous (brownish-grey) Phyllites………………….……………………34 
           4.1.1.4 Structures…………..…………………………………………………………36 
              4.1.1.4.1 Foliations……...………………………………………………………….36 
              4.1.1.4.2 Crenulations……..………………………………………….…………….36 
              4.1.1.4.3 Lithons……………………….……………………………….…………..37 
4.1.2 Mineralogical Content of the rocks .........................................................................38 
4.2 GEOCHEMISTRY ........................................................................................................39 
4.2.1 Major Elements .......................................................................................................39 
4.2.2 Trace Elements (including REEs) ...........................................................................43 
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            4.2.2.1 Large Ion Lithophile Elements (LILE)……………………………..………..43 
            4.2.2.2 Transition Metals…………………………………………………………….43 
            4.2.2.3 High Field Strength Elements (HFSE)………………………………...…….44 
            4.2.2.4 Rare Earth Elements (REEs)………………………….……………………..45 
4.2.3 Role of Metamorphism……………………………………………………………47 
4.3 GEOCHEMICAL CLASSIFICATION OF THE ROCKS ............................................48 
4.4 MINERAL CONTROLS ON MAJOR AND TRACE ELEMENT 
DISTRIBUTION..................................................................................................................50 
CHAPTER FIVE ...................................................................................................................54 
5.0 DISCUSSION ...................................................................................................................54 
5.1 IMPLICATION OF MINERALOGICAL CONTENT .................................................54 
5.2 SEDIMENTARY SORTING AND RECYCLING .......................................................56 
5.3 PROVENANCE .............................................................................................................61 
5.3.1 Source-area weathering and diagenesis ...................................................................61 
5.3.2 Source rock composition .........................................................................................68 
5.3.3 Tectonic setting of source area ................................................................................85 
5.4 CRUSTAL EVOLUTION .............................................................................................91 
5.5 LOCATION OF SOURCE AREA ................................................................................94 
CHAPTER SIX ......................................................................................................................96 
6.0 CONCLUSIONS AND RECOMMENDATIONS ........................................................96 
6.1 CONCLUSIONS ............................................................................................................96 
6.2 RECOMMENDATIONS ...............................................................................................97 
REFERENCES ......................................................................................................................98 
APPENDIX ...........................................................................................................................117 
LIST OF SAMPLE LOCATIONS……………………………………………………..…..117 
 
 
 
 
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LIST OF FIGURES 
                                                                                                                                             Page                                                                                                                                                                                          
Figure 1.1 Generalised tectono-stratigraphic map of Ghana showing the study area (modified
 after Osae et al., 2006)………….………………………….…………………..............3 
Figure 1.2 Geological map of the study area showing the sample locations…………………..5 
Figure 2.1 Geological map showing the Dahomeyide orogeny in Ghana with the location of
 study area (after Attoh, 1998)…………….………….………………........................18 
Figure 4.1 Field photograph of thinly foliated carbonaceous phyllites observed along Peduase
 road-cut. Picture taken facing northwest…………….…………………………..…..33 
Figure 4.2 Field photograph of iron-stained phyllites observed along Peduase road-cut.
 Picture taken facing northwest……..………………………………………………...34 
Figure 4.3 Field photograph of micaceous phyllites observed along Peduase road-cut. Picture
 taken facing northwest…………...…………………………………………………..35 
Figure 4.4 (a) Carbonaceous phyllite underlain by micaceous phyllites, (b) Carbonaceous
 phyllite overlain by iron-stained phyllites. Pictures taken facing northwest………...35 
Figure 4.5 Field photograph of thinly foliated phyllites observed along Peduase road-cut.
 Picture taken facing northwest………………..………………………..………..…...36 
Figure 4.6 Crenulations in phyllites observed along Peduase road-cut. Picture taken facing
 northwest………………………….…………………………………………………37 
Figure 4.7 Lithon in phyllites observed along Peduase road-cut. Picture taken facing
 northwest………………………….…………………………………………………38 
Figure 4.8 PAAS-normalized average major element compositions for the Neoproterozoic
 phyllites from the Akuapim range, southeastern Ghana. Post-Archean Australian
 average shale (PAAS) data are from Taylor and McLennan (1985)………………...40 
Figure 4.9 PAAS-normalised patterns, for Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana. Data for post-Archean Australian average shale (PAAS) are
 from Taylor and McLennan (1985)……..……..……………………………………..45 
Figure 4.10 Chondrite-normalized REE patterns in Neoproterozoic phyllites from the
 Akuapim range, southeastern Ghana. Normalizing values are from Boynton (1984).
 Post-Archean Australian average shale (PAAS) is plotted for comparison (values are
 from Taylor and McLennan, 1985)…………………………………………………..46 
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Figure 4.11 PAAS-normalized REE patterns in Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana. Post-Archean Australian average shale (PAAS) values are
 from Taylor and McLennan (1985)…………..………………………………………47 
Figure 4.12 Chemical classification of Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana (fields after Herron, 1988)………….….………………………..49 
Figure 4.13 Major element chemical classification of the Neoproterozoic phyllites from the
 Akuapim range, southeastern Ghana (after Crook, 1974)…………………………….49 
Figure 4.14 Binary plots of SiO2 versus other major elements for the Neoproterozoic phyllites
 from the Akuapim range, southeastern Ghana…………………………..……………51 
Figure 4.15 Binary plots of Al2O3 versus other major elements for the Neoproterozoic phyllites
 from the Akuapim range, southeastern Ghana………………………..………………52 
Figure 5.1 Bivariate plot of SiO2 versus Al2O3 + K2O + Na2O for the Neoproterozoic phyllites
 from the Akuapim range, southeastern Ghana (after Suttner and Dutta, 1986)……..58 
Figure 5.2 Plot of Th/Sc versus Zr/Sc for the Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (after McLennan et al., 1993). Values for felsic, andesites
 and basalts are from Condie (1993)……….…..……………………………………...60 
Figure 5.3 Ternary A-CN-K (Al2O3-CaO+Na2O-K2O) for Neoproterozoic phyllites from the
 Akuapim range, southeastern Ghana (after Nesbitt and Young, 1984; 1989).
 Average values of G: granite; A: andesite; B: basalt; values taken from Condie (1993).
 Upper Continental Crust (UCC) plotted for comparison (values taken from Taylor and
 McLennan, 1985)…….................................................................................................64 
Figure 5.4 Plot of CIA index versus ICV index for the Neoproterozoic phyllites from the
 Akuapim range, southeastern Ghana (after Potter, 2005)……….……………………66 
Figure 5.5 Plot of Th/U versus Th for Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana (after McLennan et al., 1993)………………………………..…67 
Figure 5.6 Distribution of K2O and Rb in the Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana, relative to a K2O-Rb ratio of 230 (values for K2O-Rb
 ratio are from Shaw, 1968) (after Floyd and Leveridge, 1987)………………….……70 
Figure 5.7 A ternary plot of SiO2/20-K2O+Na2O-MgO+Fe*+TiO2 for the Neoproterozoic
 phyllites from the Akuapim range, southeastern Ghana (after Roser and Korsch,
 1988)…………………………………………………………………………………71 
Figure 5.8 Discriminant function diagram for Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (after Roser and Korsch, 1988)………….……………...71 
Figure 5.9 Th/Co versus La/Sc for the Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana (fields are after Cullers, 2000)…………………………...…….75 
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Figure 5.10 A ternary plot of V-Ni-Th*10 for Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (fields are after Bracciali et al., 2007)……………….…...76 
Figure 5.11 (a) Th-Hf-Co ternary diagram and (b) La-Th-Sc ternary diagram, for
 Neoproterozoic phyllites from the Akuapim range, southeastern Ghana (compositional
 fields are after Roddaz et al., 2007). Post-Archean Australian average shale (PAAS)
 and Upper Continental Crust (UCC) are plotted for comparison (values are from
 Condie, 1993)……………...……………………………………………………...….77 
Figure 5.12 A plot of Cr/Th versus Th/Sc for the distribution of Neoproterozoic phyllites from
 Akuapim range, southeastern Ghana. Values for FVO: felsic volcanics; AND:
 andesites; BAS: basalts are from Condie (1993)……..……………………………..78  
Figure 5.13 A plot of Th/Sc versus Zr/Sc for the Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (after McLennan et al., 1993). Values for felsic, andesites
 and basalts are from Condie (1993)………………..………………………………...78 
Figure 5.14 Figure 5.14 Comparison of Chondrite – normalized REE patterns of average
 Togo phyllites and model Togo phyllites (Parameters are in Table 5.3)……….……82 
Figure 5.15 K2O/Na2O versus SiO2 diagram for the Neoproterozoic phyllites from Akuapim
 range, southeastern Ghana (fields are after Roser and Korsch, 1986)………………..87 
Figure 5.16 Plot of SiO2/Al2O3 versus K2O/Na2O for the Neoproterozoic phyllites from
 Akuapim range, southeastern Ghana. Boundary lines for different tectonic settings
 from Roser and Korsch (1986). ACM, active continental margin; PM, passive margin;
 A1, arc setting, basaltic and andesitic detritus; A2, evolved arc setting, felsitic–plutonic
 detritus…….………………………………………………………………………....87 
Figure 5.17 Plot of Th/Sc versus Sc for Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana (after McLennan and Taylor, 1991)………..…………………...89 
Figure 5.18 Plot of La/Y versus Sc/Cr for Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana (after Bhatia and Crook, 1986)…………….…………………...89 
Figure 5.19 La-Th-Sc ternary diagram for the Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (modified after Bhatia and Crook, 1986). A: oceanic island
 arc; B: continental island arc; C, D: active continental margin and passive
 margin………..………................................................................................................90 
Figure 5.20 (a) Th-Co-Zr/10 and (b) Th-Sc-Zr/10 ternary diagrams for Neoproterozoic
 phyllites from the Akuapim range, southeastern Ghana (after Bhatia and Crook, 1986).
 PM: passive margin; ACM: active continental margin; CIA: Continental island arc;
 OIA: oceanic island arc…………….....……………………………………………...90 
 
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Figure 5.21 Plot of Eu/Eu* versus (GdN/Yb)N for Neoproterozoic phyllites from the Akuapim
 range, southeastern Ghana (after McLennan and Taylor, 1991). Birimian
 metasediments and post-Archean Australian average shale (PAAS) are plotted for
 comparison (values are from Asiedu et al., 2004; Taylor and McLennan, 1985,
 respectively)………………………………………………………………………….93 
Figure 5.22 Correlation between the lithological logs of the Togo Structural Unit (after Blay,
 1991), the Voltaian (after Affaton, 1990) and the Buem Structural Unit (after Oase et
 al, 2006)………..….....................................................................................................95 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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LIST OF TABLES 
                                                                                                                                           Page 
Table 4.1 Mineralogical composition of whole rock samples of Neoproterozoic phyllites from
 the Akuapim range detected by X-ray diffraction method………..…………..……39  
Table 4.2 Chemical compositions of Neoproterozoic phyllites from the Akuapim range,
 southeastern Ghana………….…………………………..………………………...…41 
Table 4.3 Linear correlation coefficients for selected elements…………………………...…53 
Table 5.1 Range of elemental ratios of Togo Phyllite compared to the ratios in similar fractions
 derived from felsic rocks, mafic rocks, Upper Continental Crust, (UCC) and post -
 Archean Australian average shale (PAAS)………….....………..…...……………….79 
Table 5.2 Summary of geochemical characteristics of provenance types (after McLennan et
 al., 1993; 1995)………………………………………………………………………83 
Table 5.3 Results from mixing calculations……………….………………………………....84 
 
 
 
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 CHAPTER ONE 
INTRODUCTION 
1.1 BACKGROUND 
Geochemical methods furnish important information about the provenance, geological 
processes and formation history of sedimentary and metasedimentary rocks (Getaneh, 2002; 
Drost et al., 2003). This is based on the assumption that the final chemical composition of 
clastic sediments is controlled by interaction of factors such as source rock composition, 
tectonic setting, chemical weathering, and hydrodynamic sorting during transport and in the 
depositional environment and diagenetic processes (Johnsson, 1993; McLennan et al., 1993; 
Rollinson, 1993; Fedo et al., 1996). The mineralogy of detrital particles provides the principal 
evidence for the composition of source rocks (Johnsson, 1993). These detrital materials are 
generally produced by weathering of rocks which is directly controlled by climate. The 
intensity of weathering is influenced by the slope and relief of the source area (Johnsson, 
1993). The slope and relief of the source area are mainly dependent on the tectonic setting 
which is considered as the overall primary control on the composition of sedimentary rocks 
(Dickinson, 1985). Sedimentary rocks formed in different tectonic environments have 
distinctive provenance characteristics and are characterized by distinctive sedimentary 
processes as plate tectonic processes impart unique petrological and geochemical signatures to 
sedimentary rocks (Bhatia, 1983; Dickinson et al., 1983; McLennan et al., 1993).  
Chemical composition of fine-grained sedimentary rocks are particularly valuable for 
provenance studies as they provide a representative view of the average crust in the area due 
to their grain size homogeneity and post-depositional impermeability (Taylor and McLennan, 
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1985; Cox and Lowe, 1995). Chemical composition can be extracted by whole-rock 
mineralogical and geochemical analyses of the sediments (Taylor and McLennan, 1985). 
These analyses determine the mineralogical content as well as the major and trace element 
(including REEs) abundances which give significant evidence used in constraining the source 
rocks, source area weathering and tectonic setting of sedimentary and metasedimentary rocks.  
The Togo Structural Unit which forms part of the Pan-African Dahomeyide belt in 
southeastern Ghana (Figure 1.1) occurs as a north northeast to south southwest trending 
mountains and hills from the Volta River towards the Ghana-Togo border and beyond (Junner 
and Service, 1936; Junner and Hirst, 1946; Kesse, 1985). Prominent among these hills and 
mountains is the Akuapim range which is comprised of cataclastic quartzites interbedded with 
phyllites (Junner and Service, 1936; Junner and Hirst, 1946).  
The rocks of the Togo Structural Unit have been investigated by numerous workers such as 
Kitson (1928), Junner and Hirst (1946), Affaton et al. (1980), Kesse (1985), Blay (1991) and 
Amoah (2009). However, little work has addressed the Togo phyllites and its geochemical 
characteristics which can give a wealth of information about provenance and crustal evolution 
of the unit. The aims of this research are to define the geochemical characteristics of the 
Neoproterozoic phyllites from the Akuapim range of the Togo Structural Unit based on their 
major and trace elements compositions, to discuss the source-area weathering conditions and 
to constrain their provenance and tectonic setting as well as contribute to the geochemical 
database of the Neoproterozoic rocks of Ghana which can be used for any future computation 
of the Neoproterozoic crustal compositions.   
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Figure 1.1 Generalised tectono-stratigraphic map of Ghana showing the study area (modified from Osae et al., 2006).  
 
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1.2 OBJECTIVE 
The objectives of this study were to:  
1. Generate a geochemical database for the Togo phyllites;  
2. Characterize the geochemical composition of these phyllites; 
3.  Identify the source rock composition and tectonic setting of the Togo phyllites; and 
4.  Infer the source-area weathering conditions.  
 
1.3 STUDY AREA 
1.3.1 Location 
The study area is located in the southeastern part of Ghana and lies between latitudes 05˚ 45' 
30" N and 05˚ 51' 00" N and longitudes 00˚09' 40" W and 00˚14' 00" W (Figure 1.2). Notable 
towns in the study area include Aburi (which lies in the northeastern part of the study area), 
Kitase, Peduase, Agyemanti, Ayim, Ayimensa and Kponko, 
1.3.2 Accessibility 
The study area is easily accessed by the Oyarifa-Ayimensa-Aburi road, a first class road which 
leads from the southwestern to northwestern part of the study. Other parts of the study area 
can be accessed by a third class road from Kitase to Agyemanti. Most of the study area are 
linked by footpaths. However, accessibility to some parts is difficult due to the relief and 
vegetation. 
 
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Figure 1.2 Geological map of the study area showing the sample locations (modified from 
Ghana National Geological Map Project, 2009). 
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1.3.3 Topography and Drainage 
The study area consists of gentle slopes interspersed with plains in the west with the Akuapim 
range rising steeply above the western end. The Akuapim range generally lies at 375-420 m 
north of Aburi and falls to 300 m southward (Dickson and Benneh, 1988). The highest 
highlands stretch from Kitase to northwestern part of Peduase and the lowlands occur around 
Teiman. 
River Ntare and Dakobi are the major rivers which flow through the study area. River Ntare 
flows from the northwestern to the southwestern part of the area from Onyaase to Agyemanti 
and has its diversion to Gyankama and Obuom. The Dakobi River flows from the southwest 
to Teiman. The area has few seasonal streams most of which are threatened by farming 
activities. Groundwater serves as the main source of water for residents in the area. 
1.3.4 Climate 
The study area falls within the savannah agro-ecological zone (Dickson and Benneh, 1988). 
The area experiences a bi-modal rainfall pattern with the major rainy season occurring from 
March to July and minor rainy season from September to November. The average annual 
temperature ranges between 25.1OC in August and 28.4OC in February and March (Dickson 
and Benneh, 1988).  
1.3.5 Vegetation and Soil 
The vegetation of the area is generally depicted by shrub lands and grassland (Dickson and 
Benneh, 1988). The shrub lands occur mostly in the western peripheries and in the north 
towards the Aburi hills and consist of dense cluster of small trees and shrubs that grow to an 
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average height of about 5 m (Dickson and Benneh, 1988). The grassland which has now been 
encroached upon by human activities such as settlements occur to the southern parts of the 
area.  
The soil types found in the area are deep, orange brown to bright red, sandy clay loam 
containing abundant ironstone concretions and gravels which are suitable for maize, yam, 
cassava, groundnut, sweet potato, vegetables (Dickson and Benneh, 1988). 
 
1.4 GEOLOGICAL SETTING 
The geology of Ghana (Figure 1.1) can generally be divided into four tectono-stratigraphic 
units on the basis of age, tectonics and lithological characteristics of the supracrustal rocks 
(Kitson, 1928; Bates, 1955; Asihene and Barning, 1975; Hasting, 1977, 1983; Kesse, 1985; 
Blay, 1991; Davis et al., 1994). These divisions are: 
1) Early Proterozoic basement rocks, the Birimian and Tarkwaian which form the western 
units, found at the eastern margin of the West African Craton; 
2) Late Proterozoic to Early Paleozoic sedimentary cover, the Voltaian Supergroup; 
3) The Precambrian mobile belt, Dahomeyide Belt which was developed during the Pan-
African (around 600 Ma) orogeny and located in the south eastern part of the country; 
and 
4) Late Paleozoic to Early Mesozoic sedimentary basins. 
The Dahomeyide belt which is part of the Pan-African belt is believed to have resulted from 
the breakup of Rodinia supercontinent which led to the assemblage of cratonic material on the 
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northwestern part of the Gondwana supercontinent (Hoffman, 1991; Cordani et al., 2003). The 
Togo Structural Unit (Figure 1.2) forms part of the Dahomeyide belt exposed in the 
southeastern part of Ghana. It is bordered to the west by the Cape Coast granitoid complex 
rocks, Voltaian and Buem Structural Unit. To the east of the Togo Structural Unit is a generally 
low-lying area (Accra plains) underlain by high-grade, Dahomeyan metamorphic terrain. The 
Togo Structural Unit consists of quartz sericite-schists, quartzites, phyllites and chlorite 
(Robertson, 1925; Junner and Hirst, 1946; Grant, 1969). Hornstones, jaspers and hematite 
quartz-schists occur as post-depositional rocks within the unit (Junner and Service, 1936). The 
quartzites are metamorphosed and deformed. The degree of metamorphism and deformation 
increases towards the southeast (Wright et al., 1985).  
The study area is part of the Akuapim range which occurs as north northeast to south southwest 
trending mountains and hills from the Volta River towards the Ghana-Togo border and beyond 
(Kesse, 1985). It comprises of cataclastic quartzites interbedded with phyllites (Ahmed et al., 
1977). The cataclastic quartzites are the predominant members of the unit. They are generally 
grey, medium to fine-grained, thickly foliated with joints and micro-fractures. The phyllites 
underlie the quartzites and are mostly composed of mica and chlorite which are formed from 
metamorphism of clays (Ahmed et al., 1977). They are mostly grey on fresh surface, fine-
grained, thinly foliated with joints and microfractures. Folds which occur within the quartzites 
and phyllites are predominantly isoclinal with axial planes inclined to southeast at 300 to 600 
and minor recumbent folds with general dip of less than 300 (Kesse, 1985). 
 
 
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CHAPTER TWO 
 LITERATURE REVIEW 
2.1 INTRODUCTION 
In this chapter, provenance studies in fine-grained sedimentary rocks, factors that control the 
final composition of clastic sediments and their geochemical significance related to this study 
are presented. In addition, the geology of the study area which falls within the Togo Structural 
Unit, a part of the Dahomeyide Belt, is presented.  
2.1.1 Provenance studies in fine-grained sedimentary rocks 
Provenance studies of sedimentary rocks usually involve the determination of the source rock 
composition, the tectonic setting or the source area, source area weathering, and the climate 
and relief of the source area (Johnsson, 1993). Numerous workers have proposed various 
techniques and approaches for the provenance studies of fine-grained siliciclastic sedimentary 
rocks. One of the techniques is the detrital heavy mineral assemblages. This involves the 
extraction of information from heavy minerals such as garnet (Morton, 1987), chrome spinel 
(Pober and Faupl, 1988; von Eynatten, 2003), tourmaline (von Eynatten and Gaupp, 1999), 
amphibole (Faupl et al., 2002), white mica (von Eynatten et al., 1996; von Eynatten and 
Wijbrans, 2003) and epidote (Spiegel et al., 2002) for quantitative provenance studies. Another 
technique which has been used by numerous workers is the whole-rock geochemistry (e.g., 
Nesbitt and Young, 1984; Bhatia, 1985; Asiedu et al., 2004). This method involves the 
determination of major, trace as well as rare earth element abundance in sediments. These 
elements provide important information about the source rock composition, source area 
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weathering and tectonic setting of sediments (e.g., Nesbitt and Young, 1984; Bhatia, 1985; 
McLennan, 1989; McCann, 1991; McDaniel and McLennan, 1991; McLennan and Taylor, 
1991; McLennan et al., 1993; Johnsson, 1993). Other techniques such as zircon dating and 
isotope geochemistry have also been used in recent studies to determine the provenance of 
sediments (e.g., Heller and Frost, 1988; Kalsbeek et al., 2008; Chen et al., 2014; De et al., 
2015).  
2.1.2 Source rock composition of clastic sediments 
Studies have shown that the source rock composition of clastic sediments may be determined 
from their chemical composition (McLennan et al., 1993). This is based on the direct link 
between the mineralogy, chemical composition of clastic sediments and their source rock 
composition (Johnsson, 1993). However, the tectonic setting is believed to chiefly control the 
composition of clastic sediments (Pettijohn et al., 1972; Dickinson and Suczek, 1979; Bhatia, 
1983; Chamley, 1990). Plate tectonic processes impart distinctive petrological and 
geochemical signatures to sedimentary rocks (Bhatia, 1983; Dickinson et al., 1983; McLennan 
et al., 1993). Therefore, sedimentary rocks formed in different tectonic environments have 
distinctive provenance characteristics as they are characterized by distinctive sedimentary 
processes (Bhatia, 1983; Dickinson et al., 1983; McLennan et al., 1993). Studies on 
sedimentary and metasedimentary rocks by numerous workers such as Enkeboll (1982), Bhatia 
and Crook (1986), Johnsson (1993), Asiedu et al. (2004), Armstrong-Altrin et al. (2004) and 
Osae et al. (2006) support the interaction between the composition of clastic sediments, source 
rock composition and tectonic setting of source area.  
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Provenance studies of clastic sediments by geochemical methods basically involves the 
application of major and trace element (including rare-earth element) geochemistry to 
discriminate source rock composition and tectonic setting (e.g., Bhatia, 1983; Bhatia and 
Crook, 1986). The application of elemental geochemistry in identifying source rocks for 
sedimentary rocks is based on the relative immobility of certain elements such as rare-earth 
element (REEs), high field strength elements (HFSE), Cr, Co, Sc and Th during weathering, 
diagenesis, hydrothermal overprint and low-grade metamorphism (Taylor and McLennan, 
1985; Bhatia and Crook, 1986). These elements are transported, in effect quantitatively, in the 
terrigenous component of sediment and therefore, their concentration and elemental ratios are 
not the same for different types of rocks and tectonic environments and therefore, reflect their 
source composition (Roaldset, 1973; Ronov et al., 1967, 1974; Cullers et al., 1979, 1975; 
Bavinton and Taylor, 1980; McLennan et al., 1983; Bhatia, 1985; Bhatia and Crook, 1986; 
Getaneh, 2002).  
The correlation between sediments composition and tectonic setting is mostly ascertained by 
plotting the rock suites on discrimination diagrams using mineralogical and chemical 
composition of the sediments. The cluster of the rock suites that emerges is correlated with 
tectonic environment of the inferred source terrains. Different discrimination diagrams have 
been presented by previous workers such as Dickinson et al. (1983), Bhatia, (1983), Bhatia 
and Crook, (1986) and Roser and Korsch, (1986; 1988). Even though most of the inferred 
tectonic terranes proposed by these workers were mainly used for sedimentary rocks, the 
introduction of bulk-rock geochemical analyses permit them to be applied to metasedimentary 
rocks  (e.g., Bhatia and Crook, 1986; Asiedu et al., 2004; Armstrong-Altrin et al., 2004; Osae 
et al., 2006). 
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2.1.3 Chemical Weathering 
The intensity and duration of weathering are dependent on climate (i.e., rainfall, temperature) 
and relief (i.e., elevation differences, slope angle) (Johnsson, 1993). In general, chemical 
weathering is more intense in the tropics relative to the temperate and arid regions 
(Woolnough, 1930; Krynine, 1936; Mann and Cavaroc, 1973; Basu, 1976; Suttner and Basu, 
1981; Girty et al., 1988). Low relief and gentle slopes support chemical weathering because 
the duration of weathering is longer on gentle slopes (Johnsson, 1993). On the other hand, high 
relief and steep slopes support erosion and rapid removal of minerals from the weathering 
environment before they are rigorously altered by weathering processes (Johnsson, 1993). 
Under chemical weathering conditions, less stable minerals (e.g., olivine, pyroxenes, 
amphiboles, calcium plagioclase) are destroyed whiles the more stable minerals (e.g. sodium 
plagioclase, potassium feldspars, muscovite, quartz) are enriched. This is because common 
rock forming minerals have different stabilities with respect to chemical weathering processes 
(Goldich, 1938). Therefore, the principal effect of weathering on silicilastic sedimentary rocks 
is very important in the evaluation of provenance of sedimentary and metasedimentary rocks.  
Chemical weathering can be measured by the compositional changes resulting from 
mineralogical alteration and chemical changes (Okada, 1971; Folk, 1974; Nesbitt and Young, 
1984). The effect of weathering on the composition of sediments has been by numerous 
workers (Woolnough, 1930; Krynine, 1936; Goldich, 1938; Basu, 1976; Potter, 1978a; 
Nesbitt, 1979; Nesbitt et al., 1980; Suttner and Basu, 1981; Knoll and James, 1987; Hansley, 
1987; Bennet and Siegel, 1987; Mast and Drever, 1987; Johnsson et al., 1988). Nesbitt and 
Young (1982, 1984) evaluated and quantified the intensity of chemical weathering as the 
chemical index of alteration (CIA). The chemical index of alteration (CIA) is interpreted as a 
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measure of the extent of conversion of feldspars (which dominate the upper crust) to clays 
such as kaolinite (Nesbitt and Young, 1982, 1984; Fedo et al., 1995; Maynard et al., 1995). 
Chemical index of alteration (CIA) is defined as: 
CIA = 100 x [Al2O3/(Al2O3+CaO*+Na2O+K2O)]; In molecular proportions. Where CaO* 
represents the CaO in silicate only.  
However, the occurrence of post-depositional potassium (K) in older clastic rocks limits the 
use of the CIA parameter (Potter, 2005). Hence, a potassium free index such as chemical index 
of weathering (CIW) and plagioclase index of alteration (PIA) have been proposed by Harnois 
(1988) and Fedo et al., (1995), respectively.  
Plagioclase Index of Alteration is defined as:  
PIA = 100 x [(Al2O3-K2O)/(Al2O3+CaO*+Na2O-K2O)]; and 
The Chemical Index of Weathering (CIW), defined as: 
[Al2O3/(Al2O3+CaO*+Na2O)] x 100;  In molecular proportions. Where CaO* represents the 
CaO associated with the silicate fraction.  
Also, the index of compositional variability (ICV), proposed by Cox et al. (1995) and reflects 
the intensity of chemical weathering and source rock composition can be used to quantify the 
intensity of chemical weathring. Index of compositional variability (ICV) is defined as:  
[CaO+K2O+Na2O+Fe2O3(t)+MgO+MnO+TiO2]/Al2O3; In weight percents (wt%). Where 
Fe2O3(t) = total iron and CaO includes all sources of Ca.  
 
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2.1.4 Transportation of sediments 
Transport of sediments serves as an important link between source and depositional areas. 
However, various sedimentary processes occur prior to the deposition of sediments which 
affect the composition of the sediments (Johnsson, 1993). These sedimentary processes may 
include chemical weathering, abrasion, mechanical breakdown, hydrodynamic sorting and 
mixing which occur before deposition of sediments (McLennan et al., 1993). 
2.1.4.1 Abrasion and mechanical breakdown 
Abrasion and mechanical breakdown are the most important processes during transportation 
of sediments as they lead to the removal of mechanically less stable components especially 
lithic fragments and exposure of freshly unreacted mineral surfaces to chemical weathering 
(Dutta and Wheat, 1993). Highly weathered particles are susceptible to abrasion and 
mechanical breakdown during transport (Bradely, 1970). Abrasion usually leads to the 
rounding of coarser grain size sediments to finer grain size materials (Kuenen, 1962, 1964). 
According to Hubert (1962), Hayes (1967) and Pittman (1970), the process of rounding and 
reducing sediment sizes results in hydrodynamic sorting of the sedimentary materials and 
increases quartz/feldspar ratios.  
In general, abrasion and mechanical breakdown increase the concentration of mechanically 
stable minerals as well as heavy minerals including zircon and destroy less mechanically stable 
minerals such as plagioclase in sediments. Therefore, geochemical characteristics of clastic 
sediments may be used to infer the effect of abrasion and mechanical breakdown in 
sedimentary and metasedimentary rocks by evaluating the quartz/feldspar ratio and the heavy 
mineral (e.g. zircon) composition of clastic sediments. 
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2.1.4.2 Sorting and mixing 
Sorting and mixing of clastic sediments during transport affects the composition of clastic 
sediments. Hydrodynamic sorting controls the grain size composition and it is responsible for 
the differences in composition of the suspended load and bed load of most rivers during 
transport of clastic sediments (Garvanti, 1986; Koehnken, 1990; Johnsson et al., 1991). An 
example is the separation of most clay minerals and other fine materials from coarser-grained 
quartz, feldspars, and rock fragments during current transport. Additionally, compositional 
sorting owing to shape and density differences of grains results in changes in the energy and 
velocity of the transporting medium results in the enrichment of heavy minerals (Johnsson, 
1993). The degree of sorting may be deduced by evaluating the quartz/feldspar ratio 
(SiO2/Al2O3) and the accumulation of heavy minerals such as zircon in siliciclastic 
sedimentary rocks (Armstrong-Altrin, 2004). According to Mielke (1979), the geochemical 
characteristics of zirconium, Zr a predominant constituent of zircon (ZrSiO2) can be used to 
evaluate the degree of sorting in clastic sediments. 
Long transport distances characteristic of fine-grained sediments favour mixing of sedimentary 
components from different provenance and history which result in the variation of the 
composition of clastic sediments (Johnsson, 1993; Potter, 2005). The effect of mixing of 
sedimentary composition with variable history and provenance may introduce complexities in 
the interpretation of provenance (Whetten et al., 1969; Kelley and Whetten, 1969) and as such 
techniques including rare-earth elements (REEs) patterns, comparison of trace elemental ratios 
to values of known provenance and other discrimination diagrams are useful in ascertaining 
the provenance of sediments. 
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2.1.5 Diagenesis 
Burial of sediments during deposition leads to changes in the geochemical conditions within 
the burial environment which can produce intense post-depositional modifications in 
composition (Scholle and Schluger, 1979; McDonald and Surdam, 1984). Diagenesis 
generally involves the destruction or replacement of metastable grains by another mineral or 
alteration of metastable minerals to another mineral (Johnsson, 1993). One of the most 
important diagenetic processes in sedimentary rocks is cementation and the importance of this 
process can also be observed in the evaluation of petroleum reservoir rocks. According to 
Johnsson (1993), progressive diagenetic alteration produces complex sets of compositional 
modifications relative to chemical weathering, mechanical breakdown and abrasion, sorting 
and mixing effect.  
Even though the chemistry of diagenetic processes are not established, most of the reactions 
involved in this process may be very important in the studies of sedimentary and 
metasedimentary rocks (Land and Milliken, 1981; Boles, 1984; Surdam et al., 1984; Morton, 
1984; Moncure et al., 1984; Market and Al-Sharieb, 1984; Helmhod and van de Kamp, 1984; 
Franks and Forester, 1984; Morad et al., 1990). Diagenesis may result in alterations of 
sedimentary materials producing different geochemical signatures relative to the protolith and 
therefore significant loss in provenance information. Diagenetic effect in metasedimentary 
rocks may be obscured by the effect of metamorphism. However, rare-earth elements (REEs) 
and trace elements such as Th, Sc, Cr, Zr are relatively immobile during diagenesis and 
metamorphism are considered more reliable. 
 
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2.2 DAHOMEYIDE BELT 
The Dahomeyide belt is part of the 2000 km long Pan-African Trans-Saharan orogen located 
on the eastern margin of the West African Craton (Caby, 1987; Trompette, 1997). The Trans-
Saharan belt is postulated to have resulted from the breakup of Rodinia supercontinent which 
led to the assemblage of cratonic material on the northwestern part of the Gondwana 
supercontinent (Hoffman, 1991; Cordani et al., 2003). Boullier et al. (1986) maintains that the 
Pan-African Trans-Saharan belt resulted from oceanic closure and oblique collision between 
the West-African Craton and the Tuareg-Nigerian shields around 600 Ma ago.  
The Dahomeyide orogen belt is the southeastern segment of the Trans-Saharan belt and it 
occurs between the passive continental margin of West Africa Craton (WAC) and the Saharan 
Meta-Craton (SMC) (Black et al., 1979; Caby et al., 1981). It is exposed in southeastern Ghana 
and adjoining parts of Togo and Benin, its northern extension being the Iforas of Mali and the 
western Hoggar in Algeria (Affaton et al., 1991; Castaing et al. 1993; Attoh et al. 1997). The 
Dahomeyide belt has been interpreted as the product of the easterly subduction of oceanic 
lithosphere (Attoh, 1998; Agbossoumonde et al., 2004).  
In Ghana, the Dahomeyide belt can be subdivided into three domains which:  
 The Dahomeyan basement rocks; 
 The Togo structural units at the eastern and western side of the Dahomeyan basement 
rocks; and 
 The Buem Structural Unit to the western side of the Togo Structural Unit. 
 
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Figure 2.1 Geological map showing the Dahomeyide Orogeny in Ghana with the location of 
study area (after Attoh, 1998). 
 
 
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2.2.1 Dahomeyan Structural Unit 
The Dahomeyan, a type locality name which was first given by Roques (1948), belongs to the 
Pan-African terrain and underlies the Accra plains as well as the southern part of the Volta 
Region (Kesse 1985). The Dahomeyan occupies a total area of approximately 7000 square km 
(Mani, 1978). Kennedy (1964), Grant (1969) and Holm (1973) described the Dahomeyan as a 
reworked Achaean basement of the late Precambrian Pan-African orogen with records of 
polycyclic deformation. Clifford (1972) maintained that the Dahomeyan represents cratonic 
chains of reactivated continental basement and supracrustal rocks formed during the 
Neoproterozoic Pan-African orogeny. However, studies by Villeneuve and Cornée (1994) and 
Trompette (1997) suggested that the Dahomeyan represents a pre-orogenic rift phase that 
evolved to an active margin, with subduction and calc-alkialine magmatism occurring between 
700 Ma and 600 Ma and final collision against the eastern margin of the WAC at 610 – 600 
Ma and producing granulite facies metamorphism. Burke and Dewey (1972) postulated that 
the Dahomeyan belt was formed by subduction of oceanic crust and collision of two 
continental plates.  
In general, the Dahomeyan is considered to consist of two belts of felsic gneisses that alternate 
with two belts of mafic gneisses (Grant, 1967; Adjei, 1968; Holm, 1973; Kesse, 1985). The 
belts are up to 30km wide and trend in a south-southwest to north-northeast from the coastal 
plains extending into Togo (Kennedy, 1964). The acid gneisses are believed to be 
metamorphosed volcaniclastic and sedimentary rocks (Kesse, 1985). Holm (1974) described 
the mafic gneisses as relatively uniform oligoclase, andesine, hornblende and garnet gneisses 
of igneous origin and generally of tholeiitic composition. The Dahomeyan has suffered, at 
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least, two phases of metamorphism with the latter having resulted in retromorphism and 
mylonitization (Kesse, 1985). 
In recent literature, the Dahomeyan is classified into three structural units based on age and 
tectonics (Attoh et al., 1997; Attoh, 1998; Agbossoumonde et al., 2004; Attoh and Nude, 
2008). These are: (a) the deformed edge of the WAC locally referred to as the Ho-gneiss, (b) 
the suture zone representing the eastern boundary of the autochthonous WAC and (c) exotic 
rocks that form the granitoid gneiss complexes east of the suture zone. The Ho-gneiss consists 
of quartzo-feldspathic and augen-gneiss with basic intrusions of norite, pyroxenite and dolerite 
(Kesse, 1985). In general, the suture zone consists of high pressure mafic granulites locally 
referred to as Shai-Adaklu Hills and alkaline gneiss complex locally referred to as the Kpong 
complex (Attoh et al., 1997; Attoh and Nude, 2008). The exotic rocks mainly consist of felsic 
gneisses and migmatites   (Kesse, 1985). 
2.2.2 Togo Structural Unit  
The Togo Structural Unit has been investigated by numerous workers and different names 
developed for the rocks of this unit. Such names include Akwapimian (Kitson, 1928), Togo 
(Junner and Hirst, 1946), Togo Structural Unit (Affaton et al., 1980), Togo Series (Kesse, 
1985), and Togo Tectonic Unit (Blay, 1991). However, Togo Structural Unit has been 
generally accepted and used by recent workers (Asiedu et al., 2006; Osae et al., 2006). The 
Togo Structural Unit is an irregular, fault-bounded belt of metamorphosed sediments that 
comprise the series of hills and ridges (Akuapim range) which trend in a north north-east to 
south south-west from the Volta River towards the Ghana-Togo border and into northern Benin 
where it is called the Atacora Range (Kesse, 1985). The Togo Structural Unit marks the 
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western limit of a very large area affected by the Pan-African thermo-tectonic event that 
peaked at about 600-550 Ma and whose effects extend right across Nigeria (Griffis et al., 
2002). Studies by Hoffman (1999) indicated that the Togo Structural Unit is a collisional belt 
and suture zone between the West African Birimian craton and an eastern cratonic block that 
became welded together at a time the supercontinent of Gondwana was being created. The 
Togo Structural Unit is bordered to the east by a generally low-lying area (Accra plains) 
underlain by high-grade, Dahomeyan metamorphic terrain. To the west of the Togo Structural 
Unit are the Cape Coast granitoid complex rocks, the Voltaian and Buem Structural Unit.  
The Togo Structural Unit mainly consists of metamorphosed sediments which are quartzite, 
schist, phyllite and marble with some minor amounts of metavolcanics. Junner and Hirst 
(1946) suggest that the Togo Structural Unit was originally alternating arenaceous and 
argillaceous sediments which have been metamorphosed into phyllites, schists and quartzite, 
except in few places where unaltered shales and sandstones occur. Robertson (1925), Junner 
and Hirst (1946) and Grant (1969) explained that the Togo Structural Unit is predominantly 
composed of quartz-sericite-schists, quartzites, quartz-schists, sericite schist and chlorite. 
Others rocks that occur in this unit are hornstones, hematite quartz-schists, jaspers, pebbly grits 
and argillaceous schists with quartz pebbles (Junner and Service, 1936; Kesse, 1985). 
However, Junner and Service (1936) considered the hornstones, jaspers and hematite quartz-
schist as post-depositional rocks.  
The rocks of the Togo Structural Unit are metamorphosed and strongly deformed with the 
degree of metamorphism and deformation increasing toward the southeast (Wright et al., 
1985). The strong deformation is manifested by intense folds, fractures, joints and faults in the 
Togo Structural Unit which indicate a series of deformation of which the latest is related to the 
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600 Ma – 500 Ma Pan-African Orogeny event (Robertson, 1925; Crook, 1963; Kennedy, 1964; 
Grant, 1969). The Togo structural unit dates 579.4 +/- 0.8 Ma (40AR/39Ar dates from muscovite 
in the quartzites (Attoh et al., 1997). Kaslbeek et al. (2008) showed that the rocks (quartzite) 
of the Togo Structural Unit have ages (1000-1300 Ma) typical of sediments derived from 
sources outside the West African Craton and possibly from the Amazonian Craton. Studies by 
Koert (1910) suggested that the Togo Structural Unit to be younger than the Dahomeyan. This 
assertion was supported by Crook (1970), who indicated that the occurrence of Dahomeyan 
gneisses within the Togo sediments. Studies by Mani (1978) and Blay (1991) suggested that 
the Dahomeyan is older than the Togo Structural Unit because the Togo occurs as outliers in 
the Dahomeyan. Detailed studies by Affaton et al. (1980) indicated that the Togo Structural 
Unit is probably a lateral equivalent of the Kwahu Group of the Voltaian Basin. This assertion 
is supported by the Pb–Pb dating of detrital zircons from the quartzites of the Togo Structural 
Unit (Kalsbeek et al., 2008). According to Kalbeek et al. (2008), the quartzites of the Togo 
Structural Unit show zircon age distributions similar to those from the Kwahu/Bombouaka 
Group of the Voltaian Basin and therefore they may be lateral equivalents.  
Provenance studies of the Togo quartzites and phyllites have shown that the rocks of the unit 
were probably derived from an intensely weathered source area and mainly from Recycled 
Upper Continental Crust (Amoah, 2009). According to Amoah (2009), the rocks of the Togo 
Structural Unit show geochemical characteristics typical of sediments derived from stable 
continental areas and deposited on a passive continental margin.  
 
 
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2.2.3 Buem Structural Unit 
The Buem Structural Unit consists of a thick sequence of shale, sandstone, and volcanic rocks 
with subordinate limestone, tillite, grit and conglomerate. The shale and conglomerate forms 
the basal beds which are overlain by sandstones with the tillite on top of the sandstone 
(Dapaah-Siakwan and Gyau-Boakye, 2000). Volcanic rocks (lava, tuff, and agglomerate) 
interbedded with shale, limestone, and sandstone form the upper part of the Buem Structural 
Unit (Dapaah-Siakwan and Gyau-Boakye, 2000). According to Kesse (1985) the Unit can be 
divided into two sequences; a lower sequence of clastic sediments with some carbonate and 
tillite units succeeded by clastics and volcanics that include mafic flow units and pyroclastics.  
However, Junner (1940) and Blay (1991) classified the Buem structural unit into four (4) main 
units. These are (a) clastic units, (b) limestone and jasperoids, (c) serpentinites and (d) volcanic 
rocks. The clastic units form the uppermost and lowermost parts of the succession and they 
comprise of sandstones, fine-grained quartzites, siltstones and red shales (Junner, 1940). The 
sandstones overlie the basal beds of shale and the conglomerate and tillite overlie the sandstone 
(Dapaah-Siakwan and Gyau-Boakye, 2000). The jasperoids occur as series of bedded, 
normally red cherts of massive appearance and sometimes brecciated (Osae et al., 2006). 
According to Junner (1940) and Jones (1990), some of the jasperoids may have been formed 
by metasomatic alteration of clastic units, limestone and volcanic rocks. The serpentinites 
which are rich in chromite are schistose and massive. The serpentinites and volcanic rocks are 
unrelated since the serpentinites mark a continental collision at about 500 Ma whereas the 
volcanic rocks erupted probably during a period of tension related to continental break-up at 
about 650 Ma (Jones, 1990).  
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Buem Structural Unit are generally not metamorphosed, although a weak metamorphic and 
metasomatic imprints, which are marked by alterations in the volcanics, formation of quartz 
veins in the volcanics and the sandstones have been identified (Affaton et al., 1996).  
Deformation in the Buem Structural Unit are largely as the result of thrust tectonics. Studies 
by Wright et al. (1985), indicated that the thrust sheets are closely associated with 
serpentinized ultramafic bodies. The mafic and ultramafic units probably represent tectonically 
emplaced slices of paleo-oceanic crust caught up in the suturing of adjacent continental blocks 
during the Pan-African orogeny (Griffis et al., 2002). Consequently, the development of 
imbricated thrust systems and duplexes in the rocks with a large-scale thrusting towards the 
west of the unit.  
In general, folds in the rocks are not well developed but chevron folds occur in the fine-grained 
material (Kesse, 1985). The Buem generally strikes north northeast to south southwest and 
dips in the southeastern direction (Kesse, 1985). Kesse (1985) considered the Buem to be older 
than the Voltaian basin sediments. However, detailed studies by Affaton et al. (1980) indicate 
that the Buem is probably a lateral equivalent of the Kwahu Group of the Voltaian Basin. This 
assertion is supported by Kalsbeek et al. (2008), who showed that the Buem Structural Unit is 
a lateral equivalent of the Kwahu Group. 
 
 
 
 
 
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2.3 A GEOCHEMICAL APPROACH 
From studies, various techniques and approaches have been proposed for the provenance 
studies of fine-grained sedimentary and metasedimentary rocks. However, geochemical 
method was used for this study because of the fine-grained and metamorphosed nature of the 
rock samples. This method usually involves analysis of the major and trace element (including 
REEs) concentration in sediments and is mostly employed in the provenance studies of fine-
grained sedimentary rocks for the following reasons: 
a) The rare-earth elements (REEs) have low solubilities and short residence times in the 
ocean (McLennan and Taylor, 1991). This allows them to be faithfully preserved in 
terrigeneous sediments and validate their use as accurate indicators of provenance; 
b) The rare-earth elements (REEs) and high field strength elements are relatively 
immobile during diagenesis, weathering, hydrothermal overprint and low-grade 
metamorphism and therefore may provide important clues on the provenance of clastic 
sediments (McLennan et al., 1993; Johnsson, 1993; McCann, 1991; McLennan and 
Taylor, 1991; McLennan, 1989; Bhatia and Crook, 1986; Bhatia, 1985; Taylor and 
McLennan, 1985) 
c) The major and trace elements (including REES) allow for the identification of the 
occurrence and extent of some secondary processes such as weathering (Nesbitt and 
Young, 1982, 1984; McDaniel and McLennan, 1991; Cox et al., 1995; Fedo et al., 
1995, 1996).  
d) It can be used to study mineralogically altered rocks such as phyllites which would 
have been difficult to study by optical methods (Potter, 2005, Barbera et al., 2006). 
 
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CHAPTER THREE 
MATERIALS AND METHODS 
This research was carried out in two main phases. 
3.1 DESK STUDY AND FIELD WORK 
3.1.1 Desk Study 
A desk study and literature review were carried out prior to reconnaissance survey and main 
field work. These activities were performed to obtain a good knowledge of pre-existing work 
in the study area. At this stage, literature pertinent to the research were gathered and reviewed 
via electronic search and consultation of scientific journals, articles, publications and existing 
books about the study area and research interest. Literature gathered and reviewed were on 
geology of the study area, geochemistry and provenance studies of sedimentary and 
metasedimentary rocks.  
In addition, topographical and geological maps of the area were so as to decide the suitable 
time to embark on the field work, how the area could be accessed and the number of days 
needed for the field work. Field logistics required to undertake the field work were then 
acquired. The field logistics included Global Position System (GPS), topographic maps of the 
area, field notebook, dilute hydrochloric acid for carbonate test, geological hammer, tape 
measure, sample bags, marker pen and other equipment required for the fieldwork. 
 
 
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3.1.2 Field Work 
The field work basically involved rock sampling and was carried out for a period of four (4) 
weeks. The field work was preceded by a reconnaissance survey to ascertain the exposure and 
distribution of outcrops throughout the area and to learn more about the geology of the study 
area. The reconnaissance survey lasted five days and was helped by information gathered from 
pre-existing geological maps of the area. The reconnaissance survey was followed by a more 
detailed rock sampling. Rock locations and sampling were aided by extracting the coordinates 
of possible locations of phyllites in the study area, which is the rock of interest from the recent 
geological map of Ghana. These coordinates were then input into the global positioning system 
(GPS). The GPS showed positions in terms of WGS 84 geo-reference coordinates at any time. 
From the reconnaissance survey, the phyllites mostly outcropped along road cuts, pits and 
quarries in the study area. This knowledge together with the coordinates extracted from the 
recent geology of Ghana, aided in the location and sampling of rocks in the study area. During 
sampling, outcrops were described based on colour, texture and structure and accordingly 
given field names. Structural attitudes were measured where appropriate.  
About 50 representative samples of phyllites were collected from outcrops on the Akuapim 
range of the Togo Structural Unit, southeastern Ghana. These samples were taken at irregular 
intervals from locations in the study area to give a representative view of the study area. Fresh 
rock exposures were scarce due to intense tropical weathering. Great care was taken in 
collecting the least altered samples for geochemical analysis. This is because sample collection 
for geochemical studies is often hampered by deep lateritic weathering and thick soil cover 
(Asiedu et al., 2004). The samples were given identities (I.D), placed in sample bags and 
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marked with names corresponding to the sample ID and sent to the laboratory for mineralogical 
and geochemical analyses. 
3.2 LABORATORY WORK 
3.2.1 Sample preparation 
Sample preparation began with the removal of weathered surfaces by chipping until a fresh 
surface was achieved. Great care was taken in selecting the least altered samples for the 
analysis. Samples containing visible quartz veins, which may represent remobilization of 
elements, were avoided for the analysis. Any stained chips were also discarded. Rock samples 
selected for whole-rock geochemical analyses were cut into rectangular blocks with 
dimensions of about 7 centimetres in length, 3 centimetres in breadth and about 2 centimetres 
in thickness using a rock saw with a diamond blade. The samples for geochemical analysis 
were selected based on their locations to give a representative view of the study area. They 
were labelled, packed in a box and sent to the ALS laboratory in Vancouver, Canada for 
geochemical analyses.  
Some of the rock samples were then selected for mineralogical analysis by the X-Ray 
diffraction (XRD) method which was carried out at the Department of Physics of the 
University of Ghana. The X-ray diffraction (XRD) method was used because of the fine-
grained and metamorphosed nature of the sediments (from hand samples) which made it 
difficult to determine the mineralogical content of the rocks using optical methods such as 
petrographic microscope. Rock samples selected for mineralogical analyses were dried and 
pulverized using an agate hand mortar. Agate hand mortar was used as it does not contribute 
metals to sample powders as do steel or tungsten carbide components. Additionally, grinding 
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using agate hand mortar provides highly controlled conditions which aid in virtual removal of 
contamination from the mortar and pestle set itself. During grinding, the samples were 
frequently scraped from the mortar surfaces using a spatula to ensure the grinding of all 
particles. The pulverized samples were sieved (< 200 mesh) and the sieved sample reground. 
Care was taken to sweep the pestle over the powder to produce very fine powder. In order to 
avoid cross-contamination, ethanol was used to clean the mortar and pestle several times 
between samples, followed by some amount of the next sample to be ground. About 100-200 
mg of each of the powdered samples were sealed into labelled sample bags and sent to the 
laboratory for X-ray diffraction analysis. 
3.2.2 Mineralogical analysis 
Ten (10) rock (phyllites) samples were selected for mineralogical analysis using the X-ray 
diffraction (XRD) method at the Department of Physics of the University of Ghana. 
Mineralogical analyses were carried out on the selected samples for phase (mineral) 
identification and quantification. The samples were selected based on the colour and 
compositional differences of the various phyllites observed in the field. The XRD whole-rock 
analyses were conducted using a PANalytical Empyrean series 2 diffractometer with the 
setting conditions of Cu-Kα, 45 kV, 40 mA, slits (divergence slit size = 0.4354 mm, receiving 
slit size = 0.38 mm).  
X-ray diffraction (XRD) analysis involved the use of an X-ray tube, a sample holder and an 
X-ray detector. About 0.5 g of very fine pulverized sample was tightly packed in the sample 
holder as loose powders will give poor intensities. The sample was then rotated in the path of 
the collimated X-ray beam. As the sample and detector are rotated, the intensity of the reflected 
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X-rays is recorded. When the geometry of the incident X-rays striking the sample satisfies the 
Bragg Equation, constructive interference occurs and a peak in intensity is detected. The 
detector records and processes this X-ray signal converting it to a count rate which is then 
output to a computer monitor. The semi-quantitative percentages of mineral phases were 
obtained by the Rietveld method on the basis of the published crystal structure data. Depending 
on the structure and matrix, the detection limit is specified between 0.5 and 5 wt%. The total 
of all mineral phases detected was recalculated to 100 %. 
3.2.3 Geochemical analysis 
Twenty-eight (28) selected samples were sent to the ALS laboratory mentioned above for their 
whole rock major and trace elements (including REEs) analyses. Major and trace elements 
analyses were carried out by inductively coupled plasma-atomic emission spectrometry (ICP-
AES) and multi elements fusion Inductively Coupled Plasma-Mass spectrometry (ICP-MS), 
respectively. Loss of ignition was determined at 10000C. For the major elements analyses, a 
mixture of about 0.200g of prepared sample and lithium metaborate was fused in a furnace at 
10250C. The resulted melt was then cooled and dissolved in an acid mixture. The acid mixture 
contained nitric, hydrochloric and hydrofluoric acids. The solution was then analysed by 
Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) for the major element 
composition.  
The trace element analyses were performed observing the protocols as for the major element 
analyses. However, here the prepared sample weighed 0.100g and the analysis was done by 
the Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). The base metals were analysed 
using the ICP-AES. A 0.25 g prepared sample was digested with perchloric, nitric, 
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hydrochloric and hydrofluoric acids. Dilute hydrochloric acid was then added to the residue 
and the solution was analysed by the ICP-AES. Results obtained were corrected for spectral 
inter-element interferences (ALS laboratory). Precision is better than 2%. 
3.2.4 Data analyses 
The results from both the field work and laboratory work were compiled into tables, diagrams, 
graphs and maps using computer software such as Microsoft excel, Corel draw version x4, 
Geochemical Data Toolkits (GCD kit) version 2.3, Delta software version 5.6.5, ArcGIS and 
MapInfo professional. 
Delta graph software version 5.6.5 was used to plot variation diagrams, ternary diagrams and 
discrimination diagrams. Coreldraw version X4 was then used the draw the fields and the 
domains on the plots. Statistical analysis, mainly the calculation of correlation coefficient for 
the various elements was also carried out using the Microsoft excel. MapInfo professional and 
ArcGIS were used to develop the geological maps.  
 
 
 
 
 
 
 
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CHAPTER FOUR 
RESULTS 
4.1 PETROGRAPHY 
4.1.1 Field Observations 
Phyllites in the study area form prominent exposures and outcrop in many localities including 
Kponkpo, Agyemanti, Ayimensa, Aburi and Peduase. In hand specimen, the phyllites are 
mostly grey to reddish brown, fine-grained and thinly foliated. In general, the phyllites are 
composed of quartz, and muscovite with some amount of feldspars. Most of the phyllites 
observed along road-cuts are highly weathered and brittle which made sampling difficult in 
the study area. Three varieties of phyllites occur within the study area based on colour and 
composition. The three varieties of phyllites observed are carbonaceous (dark-grey) phyllites, 
iron-stained (reddish) phyllites and micaceous (brownish-grey) phyllites. 
4.1.1.1 Carbonaceous (dark-grey) Phyllites 
The carbonaceous (dark grey) phyllites were observed along Peduase road-cut and Kponkpo. 
In hand specimen (Figure 4.1), the carbonaceous phyllites are dark-grey, fine-grained and 
thinly foliated. These phyllites fizz when drops of dilute (5% to 10%) hydrochloric acid were 
placed on them indicating the presence of carbonate minerals. From hand samples, phillites 
showed quartz, pyrite and some amount of feldspar. The pyrite minerals were observed along 
the foliation planes of the phyllites suggesting a post-depositional process. The presence of 
pyrite in the phyllites indicates sulphate and organic content in the sediments. The 
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carbonaceous phyllites are thinly foliated and crenulated. The dark grey coloration of the 
phyllites is probably due to the presence of organic carbon (graphite) (Potter et al., 1980). 
 
Figure 4.1 Field photograph of thinly foliated carbonaceous phyllites observed along Peduase 
road-cut. Picture taken facing northwest. 
 
4.1.1.3 Iron-stained (reddish) Phyllites 
The iron-stained (reddish) phyllites were observed at Agyemanti, along the Peduase road-cut 
and Kponkpo. Mesoscopically (Figure 4.2), the rock is reddish, fine-grained with thin 
foliations. From hand samples, phyllites contain quartz, siderite and some feldspar content. 
The presence of siderite is indicative of the presence of sulphate and organics, probably 
associated with freshwater (Kholodov and Butuzowa, 2008). The reddish phyllites did not fizz 
when drops of dilute (5% to 10%) hydrochloric acid were placed on them. The reddish 
coloration of the phyllites is probably due to the oxidization of iron oxide in the rocks. The 
iron-stained phyllites are weathered and contain some clay minerals. 
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Figure 4.2 Field photograph of iron-stained phyllites observed along Peduase road-cut. Picture 
taken facing northwest.  
 
4.1.1.3 Micaceous (brownish-grey) Phyllites 
The micaceous (brownish-grey) phyllites observed occur in Agyemanti, along Peduase road-
cut and Kponpko. These phyllites are brownish-grey, fine-grained and thinly foliated (Figure 
4.3). From hand samples, phyllites are composed of quartz, chlorite and some feldspar content 
(Table 4.1). The brownish-grey phyllites did not fizz when drops of dilute (5% to 10%) 
hydrochloric acid were placed on them. The micaceous phyllites are highly weathered and 
contain some clay minerals such as illite.  
From field relations, the micaceous phyllites underlie the carbonaceous (dark-grey) phyllites 
which is overlain by the iron-stained (reddish) phyllites (Figure 4.4).  
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Figure 4.3 Field photograph of micaceous phyllites observed along Peduase road-cut. Picture 
taken facing northwest. 
 
            
Figure 4.4 (a) Carbonaceous phyllite underlain by micaceous phyllites, (b) Carbonaceous 
phyllite overlain by iron-stained phyllites. Pictures taken facing northwest. 
 
 
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4.1.1.4 Structures 
The rocks within the study area have undergone deformation which is characterized by the 
presence of foliations, crenulations, lithons observed in the phyllites.   
4.1.1.4.1 Foliations 
The phyllites of the study area are thinly foliated with an average thickness of about 0.2 cm 
(Figure 4.5). In general, the foliation surface strikes northeast-southwest and dip in the 
southeastern direction (Kesse, 1985). 
 
Figure 4.5 Field photograph of thinly foliated phyllites observed along Peduase road-cut. 
Picture taken facing northwest 
 
4.1.1.4.2 Crenulations 
The phyllites of the study area have several crenulations which depict deformation probably 
due to tensile stress exerted on the rock.  
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Figure 4.6 Crenulations in phyllites observed along Peduase road-cut. Picture taken facing 
northwest. 
 
4.1.1.4.3 Lithons 
In general, the rocks found within the study area are phyllites and quartzites with the quartzites 
overlying the phyllites. However, at some places in the study area, the quartzites occur as 
lithons within the phyllites. These structures were observed along the Peduase road-cut. This 
structure formed probably due to the tensile stress which occurred in the rock which causes 
the more competent rock to stretch and break into oval shape. The lithons are sheared and the 
direction of shearing in the southeastern direction.  
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Figure 4.7 Lithon in phyllites observed along Peduase road-cut. Picture taken facing northwest. 
 
4.1.2 Mineralogical Content of the rocks 
The mineralogical compositions of the analysed phyllites are given in Table 4.1. These include 
three (3) samples of carbonaceous (dark-grey), four (4) samples of iron-stained (reddish) 
phyllites and three (3) samples of micaceous (brownish -grey) phyllites. Quartz is the abundant 
mineral with concentrations between 30-49 wt% (average 35.5 wt%). The results show 
relatively high contents of muscovite and chlorite of 8-27 wt% (average 17.8 wt%) and 15-25 
wt% (average 17.2 wt%), respectively. The phyllites also have relatively low feldspar content 
of 10-20 wt% (average of 14.6 wt%). Samples KP8A, KP16B and KP18A which are the 
carbonaceous (dark-grey) phyllites sampled exhibit calcium carbonate (CaCO3) and graphite 
contents of 6-21 wt% and 13-21 wt%, respectively. The iron-stained (reddish) phyllites 
(samples KP2A, KP10A, KP15A and KP19A) show siderite content of 10-18 wt%. Sample 
KP18A show illite content of 9 wt%. 
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Table 4.1 Mineralogical composition of whole rock samples of Neoproterozoic phyllites from 
the Akuapim range detected  
KP KP16 KP18 KP2 KP10 KP15 KP19 KP1 KP3 KP5
Sample 8A B A A A A A A A A 
Minerals (wt%)          
Quartz 30 32 31 35 49 32 31 47 30 37 
Feldspar 11 12 12 14 10 13 16 20 24 13 
Muscovite 13 8 9 19 13 15 27 18 23 25 
Chlorite 10 12 18 15 16 22 16 15 23 25 
Siderite    17 12 18 10    
CaCO3 21 15 6        
Graphite 15 21 15        
Illite   9        
 
4.2 GEOCHEMISTRY 
The results of major and trace element (including REEs) analyses of twenty eight (28) rock 
samples of Neoproterozoic phyllites from the Akuapim range of the Togo Structural Unit are 
listed in Table 4.2.  
4.2.1 Major Elements 
The phyllites have relatively high SiO2 concentrations of 52.6-94.1 wt% (average 75.14 wt%). 
They show somewhat variable and high concentrations of Al2O3 ranging from 4.7-20.41 wt% 
(average 13.25 wt%) and relatively high concentrations of K2O between 0.77 to 6.38 wt% 
(average 3.90 wt%). The results also show low TiO2, MgO, MnO, CaO and Na2O 
concentrations of 0.12 – 1.06 wt%, 0.07-1.75 wt%, 0.01-0.77 wt%, 0.01-0.02 wt% and 0.01-
0.46 wt%, respectively. In addition, the phyllites exhibit relatively low Fe2O3 concentrations 
averaging 3.09 wt%. The phyllites exhibit variable and relatively high SiO2/Al2O3 values of 
2.98-30.55 (average 8.17). They also show high K2O/Na2O and Al2O3/TiO2 values of 8.93-
139.00 with an average of 54.31 and 18.31-33.57 (average 21.87), respectively. 
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From the calculation of the chemical index of alteration (CIA), the phyllites have high CIA 
values of 70.88-79.92 % (average 74.73 %). The phyllites also show relatively high plagioclase 
index of alteration (PIA) and chemical index of weathering (CIW) values of 94.97-98.94 % 
(average 97.68 %) and 96.20-99.28 % (average 98.36 %), respectively. Additionally, the 
phyllites have low index of compositional variability (ICV) values of 0.34-1.40 (average 0.64). 
Comparing with the Post-Archean Australian (average) Shale (PAAS; Taylor and McLennan, 
1985), the phyllites show general depletion in major oxides with the exception of SiO2 and 
MnO which are enriched relative to PAAS (Figure 4.8).  
 
 
 
Figure 4.8 PAAS-normalized average major element compositions for the Neoproterozoic 
phyllites from the Akuapim range, southeastern Ghana. Post-Archean Australian (average) 
Shale (PAAS) data are from Taylor and McLennan (1985). 
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Table 4.2 Chemical compositions of the Neoproterozoic phyllites from the Akuapim range, southeastern Ghana 
Sample KP1A KP2A KP3A KP4A KP5A KP6A KP7A KP8A KP9A KP10A KP11A KP11B KP12A KP13A 
Major oxides (wt%)               
SiO2 68.8 62.3 71.5 93.4 90.5 86.7 82.3 52.6 90.4 94.1 70.7 73.4 79 76.8 
TiO2 1.06 0.99 0.9 0.2 0.17 0.35 0.45 0.77 0.2 0.12 0.7 0.71 0.54 0.56 
Al2O3 20.1 19.65 17.95 4.92 4.75 7.46 8.3 15.25 4.57 3.08 16.1 13.55 12 12.2 
Fe2O3 0.81 4.04 1.4 0.41 0.42 2.19 4.06 13.95 1.85 1.28 2.57 2.65 1.37 1.4 
MnO <0.01 0.01 <0.01 <0.01 <0.01 <0.01 0.01 0.77 0.01 0.01 <0.01 <0.01 <0.01 <0.01 
MgO 0.21 1.28 0.62 0.16 0.16 0.11 0.12 1.66 0.29 0.07 1.08 0.85 0.71 0.73 
CaO 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.17 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 
Na2O 0.46 0.1 0.12 0.02 <0.01 0.06 0.07 0.14 0.02 0.01 0.08 0.06 0.05 0.05 
K2O 4.74 6.38 5.04 1.39 1.39 2.05 2.34 4 1.11 0.77 5.61 4.67 4.29 4.51 
P2O5 0.03 0.02 0.01 0.01 <0.01 0.01 0.02 0.1 0.01 0.01 0.01 0.01 <0.01 0.01 
LOI 3.43 3.93 3.36 1.08 1.1 1.6 1.98 8.88 1.17 1.1 3.09 2.69 2.21 2.24 
Total 99.67 98.72 100.92 101.61 98.53 100.55 106.56 90.58 99.57 102.55 99.56 98.13 100.23 98.79 
               
CIA 77.24 73.44 75.99 75.98 75.53 76.16 75.8 78.49 78.01 72.13 72.38 71.67 71 72.77 
PIA 94.97 98.45 98.3 98.53 98.94 97.82 95.29 98.51 98.48 98.53 98.64 98.65 98.65 98.24 
CIW 96.2 98.99 98.81 98.97 99.28 98.46 96.58 98.89 98.89 99.08 99.14 99.17 99.18 98.87 
ICV 0.34 0.65 0.44 0.44 0.45 0.63 1.4 0.76 0.73 0.62 0.66 0.58 0.59 0.58 
               
SiO2/Al2O3 3.42 3.17 3.98 18.98 19.05 11.62 3.45 19.78 30.55 4.39 5.42 6.58 6.3 5.89 
K2O/Na2O 10.3 63.8 42 69.5 139 34.17 28.57 55.5 77 70.13 77.83 85.8 90.2 54.88 
K2O/Al2O3 0.24 0.32 0.28 0.28 0.29 0.27 0.26 0.24 0.25 0.35 0.34 0.36 0.37 0.34 
Al2O3/TiO2 18.96 19.85 19.94 24.6 27.94 21.31 19.81 22.85 25.67 23 19.08 22.22 21.79 20.79 
               
Trace elements (ppm)             
Sc 14 16 14 3 3 5 7 14 3 3 12 10 10 11 
V 115 118 90 17 17 28 36 106 19 15 80 61 65 69 
Cr 90 70 60 20 20 30 40 60 20 10 40 40 40 40 
Co <1 3 1 <1 1 2 5 25 5 2 4 3 4 4 
Ni 5 10 11 5 7 5 9 24 14 14 7 8 11 10 
Cu 3 10 2 4 4 10 23 5 6 12 17 11 5 5 
Rb 154 210 165 41.4 41.6 63.8 68.1 126.5 35.4 24 158.5 137 117.5 120 
Sr 205 33.5 46.9 11.6 10.6 37 44.3 82.7 13.5 9.5 24.7 20.6 13.8 14.2 
Cs 3.8 5.41 3.62 0.81 0.77 1.44 1.69 3.2 0.7 0.5 4.71 4.09 2.85 2.98 
Ba 1575 1165 945 228 223 411 437 777 281 155.5 978 843 755 775 
Y 33.2 47.8 34.4 14.4 13.4 19.1 27.8 39.4 11.6 10 26.7 24.9 16.3 17.2 
Zr 479 559 460 407 331 542 594 285 271 274 406 468 378 387 
Hf 12.3 14.7 11.8 10 8.4 13.2 15.3 7.7 7.1 6.6 10.5 12 9.8 9.9 
Nb 20 18.2 18.3 4.6 4.2 7 8.8 15.4 4 2.7 13.6 14.2 9.7 10 
Ta 1.4 1.3 1.3 0.3 0.3 0.5 0.6 1.1 0.3 0.2 0.9 1 0.7 0.7 
Th 18.55 17 17.35 4.73 4.21 6.85 9.83 16.75 4.39 2.84 13 13.55 9.43 9.84 
U 3.92 5.06 4.69 1.67 1.52 2.95 2.8 4.21 1.28 1.14 3.36 3.45 3.05 3.13 
La 50.8 30.9 41.7 18.2 16.9 22.7 31.5 44.9 19.4 10.7 36.9 34.9 23.6 24.3 
Ce 99.8 69.7 81.4 41 39 52.5 73.1 94.8 37.4 24.3 75.1 71.5 50.1 51.2 
Pr 10.35 7.71 9.11 4.94 4.59 5.97 8.27 10.5 4.12 2.94 8.34 7.84 5.43 5.46 
Nd 35.8 30.2 34 18.6 18.4 23.8 33.1 42 15.9 12.2 30.7 29 19.7 20.8 
Sm 6.11 6.66 6.62 3.9 3.43 4.77 6.04 8.69 2.85 2.54 5.41 5.21 3.45 3.39 
Eu 1.16 1.31 1.21 0.57 0.58 0.78 1.2 1.6 0.54 0.43 0.97 0.87 0.58 0.61 
Gd 4.86 6.78 5.61 3.15 2.75 3.39 5.06 7.91 2.28 1.87 4.34 3.69 2.57 2.68 
Tb 0.86 1.28 0.92 0.41 0.43 0.52 0.79 1.16 0.32 0.3 0.74 0.64 0.41 0.43 
Dy 6.02 8.46 6.12 2.63 2.48 3.35 5.17 7.35 2.15 1.78 4.97 4.41 2.92 3.01 
Ho 1.22 1.82 1.27 0.53 0.54 0.68 1.05 1.42 0.44 0.38 1.06 0.95 0.62 0.67 
Er 3.64 5.56 3.85 1.66 1.41 2.02 2.78 4.27 1.32 1.05 2.96 2.83 2.18 2.32 
Tm 0.54 0.77 0.57 0.25 0.18 0.32 0.43 0.55 0.19 0.16 0.47 0.44 0.31 0.33 
Yb 3.75 5.12 3.86 1.44 1.41 2.23 2.94 3.96 1.48 1.06 3.3 3.11 2.28 2.51 
Lu 0.6 0.73 0.6 0.27 0.23 0.34 0.45 0.58 0.22 0.16 0.48 0.49 0.37 0.39 
               
Rb/Sr 0.75 6.27 3.52 3.57 3.92 1.72 1.54 1.53 2.62 2.53 6.42 6.65 8.51 8.45 
Th/U 4.73 3.36 3.7 2.83 2.77 2.32 3.51 3.98 3.43 2.49 3.87 3.93 3.09 3.14 
Th/Sc 1.33 1.06 1.24 1.58 1.4 1.37 1.4 1.2 1.46 0.95 1.08 1.36 0.94 0.89 
Cr/Th 4.85 4.12 3.46 4.23 4.75 4.38 4.07 3.58 4.56 3.52 3.08 2.95 4.24 4.07 
               
∑REE 225.51 177 196.84 97.55 92.33 123.37 171.88 229.69 88.61 59.87 175.74 165.88 114.52 118.1 
LaN/YbN 9.13 4.07 7.28 8.52 8.08 6.86 7.22 7.64 8.84 6.81 7.54 7.57 6.98 6.53 
LaN/SmN 5.23 2.92 3.96 2.94 3.1 2.99 3.28 3.25 4.28 2.65 4.29 4.21 4.3 4.51 
GdN/YbN 1.05 1.07 1.17 1.77 1.57 1.23 1.39 1.61 1.24 1.42 1.06 0.96 0.91 0.86 
Eu/Eu* 0.65 0.6 0.61 0.5 0.58 0.59 0.66 0.59 0.65 0.6 0.61 0.61 0.6 0.62 
CIA = [Al2O3/(Al2O3 + CaO* + Na2O + K2O)] × 100, PIA = 100 x [(Al2O3-K2O)/(Al2O3+CaO*+Na2O-K2O)],  
CIW = [Al2O3/(Al2O3+CaO∗+Na2O)]×100, ICV = [CaO+K2O+Na2O+Fe2O3(t)+MgO+MnO+TiO2]/Al2O3, 
Eu/Eu* = EuN/(SmN*Gd
½
N) , where N refers to normalized values.  
Normalizing values are from Boynton (1984). 
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Table 4.2 continued. Chemical compositions of Neoproterozoic phyllites from the Akuapim range, southeastern Ghana 
KP14 KP14 KP15 KP15 KP16 KP17 KP17 KP18 KP18 KP19 KP19 NP13
Sample NP11 NP12 
A B A B A A B A B A B B 
Major oxides (wt%)               
SiO2 77.2 83.1 70 74 79.2 77.1 90.1 64.8 76 69.3 68 60.75 61.54 60.36 
TiO2 0.63 0.39 0.8 0.8 0.55 0.68 0.14 0.9 0.69 0.88 0.84 0.934 0.848 0.882 
Al2O3 13.1 9.15 16.6 14.65 11.85 12.95 4.7 17.4 12.75 19.85 18.6 20.41 19.67 19.31 
Fe2O3 1.7 1.3 2.26 2.25 1.5 1.39 0.59 6.79 2.21 1.91 4.04 7.05 6.61 8.46 
MnO 0.01 <0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.005 0.022 0.221 
MgO 0.88 0.62 1.18 1.07 0.78 0.82 0.28 1.13 0.81 0.22 0.23 0.71 1.75 1.51 
CaO 0.01 <0.01 <0.01 <0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 <0.01 <0.01 
Na2O 0.08 0.03 0.08 0.06 0.06 0.09 0.03 0.13 0.1 0.38 0.33 0.45 0.34 0.4 
K2O 4.39 3.41 5.97 5.15 4.21 4.25 1.5 5.65 4.53 5.19 4.55 4.02 4.1 3.91 
P2O5 0.01 0.01 0.02 0.01 0.02 0.02 0.05 0.02 0.02 0.03 0.04 0.1 0.05 0.08 
LOI 2.51 1.7 2.91 2.76 2.2 2.57 1.1 3.81 2.48 3.72 3.69 5.3 4.17 4.8 
99.74
Total 99.71 100.94 99.69 99.99 100.39 99.89 98.51 100.65 99.61 101.5 100.34 99.11 99.943 
9 
               
CIA 70.88 71.52 72.02 75.69 71.72 73.1 73.54 73.27 71.49 76.02 77.22 79.92 79.68 79.73 
PIA 98.78 98.54 98.73 97.74 98.42 98.05 97.85 97.99 97.72 95.68 96.06 95.39 96.35 95.71 
CIW 99.27 99.11 99.21 98.42 99.02 98.73 98.58 98.68 98.59 96.86 97.07 96.33 97.15 96.62 
ICV 0.63 0.62 0.63 0.84 0.6 0.55 0.54 0.83 0.65 0.41 0.52 0.62 0.68 0.78 
               
SiO2/Al2O3 9.08 4.22 5.05 9.92 6.68 5.95 19.17 3.72 5.96 3.49 3.66 2.98 3.13 3.13 
113.6
K2O/Na2O 74.63 85.83 33.43 70.17 47.22 50 43.46 45.3 13.66 13.79 8.93 12.06 9.78 
7 
K2O/Al2O3 0.37 0.36 0.35 0.28 0.36 0.33 0.32 0.32 0.36 0.26 0.24 0.2 0.21 0.2 
Al2O3/TiO2 23.46 20.75 18.31 18.44 21.55 19.04 33.57 19.33 18.48 22.56 22.14 21.85 23.2 21.89 
               
Trace elements (ppm)             
Sc 10 7 14 12 9 12 3 17 12 15 17 19 19 19 
V 58 37 88 79 51 69 27 114 74 88 97 87 90 84 
Cr 40 30 50 60 40 50 20 70 50 60 70 63 65 62 
Co 3 2 4 2 1 1 <1 3 2 1 <1 3 14 22 
Ni 8 3 9 8 5 10 4 10 4 8 3 <20 21 22 
Cu 7 2 4 3 3 1 1 38 10 12 19 18 21 32 
Rb 124.5 95.4 170 147.5 120 128 44.7 161.5 126.5 172 165 200 209 190 
Sr 18.4 17.5 25.2 21.2 22.9 29.9 18.7 32.2 30.2 75.9 78.7 70 60 74 
Cs 3.64 3.02 4.72 4.26 3.93 4.35 1.49 5.46 4.46 4.81 4.75 7.9 7.8 9.5 
Ba 759 680 1050 892 651 772 260 789 622 875 840 579 647 591 
Y 24.7 25.3 41.5 31.7 21.9 33.7 9.3 34.1 25.9 34.7 42.6 30 32 36 
Zr 571 719 486 568 374 558 132 320 349 517 429 196 182 184 
Hf 14.8 16.9 12.5 14.5 10.1 13.7 3.4 8.4 9.1 13.5 11.3 5.6 5.7 5.8 
Nb 12.4 8.4 16.4 16.2 11.6 13.2 2.7 17.4 12.9 18.7 17.5 17 17 18 
Ta 0.8 0.6 1.2 1.2 0.8 1 0.2 1.2 1 1.4 1.3 1.5 1.5 1.4 
Th 12.5 8.93 17.05 16.8 11.45 13.45 4.06 17.65 12.65 19 19.85 22.7 20.9 21.1 
U 3.13 2.55 3.66 3.89 2.95 2.96 0.94 4.78 2.84 4.54 4.51 2.9 2.9 3.3 
La 31.5 28.8 60.7 37.2 33.4 44.4 122 35.3 32.4 42.6 46 50.5 50.5 56.6 
Ce 66.2 65.3 139.5 76 73.3 100.5 261 87.1 68.1 77.8 92.1 106 112 131 
Pr 7.31 7.21 16.65 8.51 8.08 11.2 26.4 9.87 7.74 8.28 10.55 10.9 11.4 13.6 
Nd 28.5 27.7 67.3 31.9 30 44.3 95.5 39.1 28.4 29.6 41.7 39.6 42.3 51.7 
Sm 5.24 4.92 12.95 5.79 5.32 8.79 13.85 7.9 5.07 5.52 8.03 7.7 8.3 10.2 
Eu 0.95 0.93 2.2 1.11 0.99 1.59 2.39 1.3 1.01 1.1 1.21 1.34 1.41 1.81 
Gd 4.11 4.32 9.6 4.73 4.09 7.51 6.51 6.34 4.01 5.32 7.89 6.1 6.4 8.2 
Tb 0.66 0.66 1.37 0.79 0.63 1.11 0.56 0.99 0.69 0.9 1.26 1 1.1 1.3 
Dy 4.55 4.34 7.72 5.87 3.91 6.45 2.45 6.37 4.84 6.09 7.93 6 6.5 7.3 
Ho 0.96 0.93 1.59 1.22 0.88 1.29 0.37 1.32 0.98 1.3 1.6 1.2 1.3 1.4 
Er 2.87 2.64 4.62 3.5 2.63 3.75 1.08 3.86 3.16 3.93 4.77 3.6 3.9 4.2 
Tm 0.44 0.42 0.66 0.57 0.43 0.52 0.14 0.61 0.43 0.6 0.65 0.58 0.63 0.66 
Yb 3.14 2.89 4.51 3.92 2.72 3.64 0.82 3.86 3.07 4.08 4.63 3.6 3.7 3.9 
Lu 0.49 0.47 0.7 0.61 0.42 0.51 0.14 0.58 0.45 0.59 0.72 0.5 0.54 0.58 
               
Rb/Sr 6.77 5.45 6.75 6.96 5.24 4.28 2.39 5.02 4.19 2.27 2.1 2.9 3.5 2.6 
Th/U 3.99 3.5 4.66 4.32 3.88 4.54 4.32 3.69 4.45 4.19 4.4 7.8 7.1 6.5 
Th/Sc 1.25 1.28 1.22 1.4 1.27 1.12 1.35 1.04 1.05 1.27 1.17 1.19 1.1 1.11 
Cr/Th 3.2 3.36 2.93 3.57 3.49 3.72 4.93 3.97 3.95 3.16 3.53 2.79 3.12 2.93 
               
156.9 238.6 249.9
∑REE 151.53 330.07 181.72 166.8 235.56 533.21 204.5 160.35 187.71 229.04 292.45 
2 2 8 
LaN/YbN 6.76 6.72 9.07 6.4 8.28 8.22 100.31 6.17 7.12 7.04 6.7 9.46 9.2 9.78 
LaN/SmN 3.78 3.68 2.95 4.04 3.95 3.18 5.54 2.81 4.02 4.85 3.6 4.13 3.83 3.49 
GdN/YbN 1.06 1.21 1.72 0.97 1.21 1.66 6.41 1.33 1.05 1.05 1.38 1.37 1.4 1.7 
Eu/Eu* 0.63 0.62 0.6 0.65 0.65 0.6 0.77 0.56 0.68 0.62 0.46 0.6 0.59 0.61 
 
CIA = [Al2O3/(Al2O3 + CaO* + Na2O + K2O)] × 100, PIA = 100 x [(Al2O3-K2O)/(Al2O3+CaO*+Na2O-K2O)],   
CIW = [Al2O3/(Al2O3+CaO∗+Na2O)]×100, ICV = [CaO+K2O+Na2O+Fe2O3(t)+MgO+MnO+TiO2]/Al2O3, 
Eu/Eu* = EuN/(SmN*GdN)
½, where N refers to normalized values.  
Normalizing values are from Boynton (1984). 
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4.2.2 Trace Elements (including REEs) 
Concentrations and elemental ratios of trace elements such as large ion lithophile elements 
(LILE) (e.g., K, Sr, Rb, Cs, Ba, Pb), transition metals (e.g., Ni, Cr, Co, V, Sc), high field 
strength elements (HFSE) (e.g., Zr, Hf, Nb, Ta, Ti, Y), and rare-earth elements (REE) (La-Lu) 
are listed in Table 4.2 above.  
4.2.2.1 Large Ion Lithophile Elements (LILE) 
The phyllites show high concentrations of Rb and Ba of 24 to 210 ppm (average 125.6 ppm) 
and 155.5-1275 ppm (average 698.41 ppm), respectively. They also show Sr and Cs 
concentrations of 9.5-205 ppm (average 40.8 ppm) and 0.5-9.5 ppm (average 3.8) ppm, 
respectively (Table 4.2) and Rb/Sr values of 0.75-8.51 (average 4.2).  
In comparison with the Post-Archean Australian (average) Shale(PAAS; Taylor and 
McLennan, 1985), the phyllites exhibit relative depletion of Sr and Cs whereas Rb and Ba have 
average to above-average concentrations, with the exception of samples KP4A, KP5A and 
KP6A which show depletion in Rb and Ba relative to PAAS (Figure 4.9).  
4.2.2.2 Transition Metals 
In general, the phyllites show low concentrations of Sc, V and Cr of 3-19 ppm (average 11.09 
pm), 15-118 ppm (average of 67.11 ppm) and 20-90 ppm (average of 46.8 ppm), respectively 
(Table 4.2). They also show low concentrations of Co and Ni of 1-25 ppm (average 4.34 ppm) 
and 3-24 ppm (average 9.82 ppm), respectively. The phyllites have relatively high Cr/Ni values 
of 0.71-23.33 (average 6.29) (Table 4.2).  
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In comparison with the Post-Archean Australian (average) Shale(PAAS; Taylor and 
McLennan, 1985), the phyllites show general depletion of V, Cr, Co and Ni with the exception 
of samples KP8A and NP13B which are slightly enriched in Co relative to the PAAS (Figure 
4.9).  
4.2.2.3 High Field Strength Elements (HFSE) 
The phyllites have high concentrations of Zr ranging from 184-719 ppm (average 408.1 ppm). 
The phyllites also show Y, Hf and Nb concentrations of 9.3-42.6 ppm (average 27.1 ppm), 3.4-
16.9 ppm (average 10.52 ppm) and 2.7-18.7 ppm (average 12.5 ppm), respectively. They 
exhibit Ta, Th and U concentrations of 0.2-1.5 ppm (average 0.92 ppm), 2.8-22.7 ppm (average 
13.1 ppm) and 0.9-5.1 ppm (average 3.2 ppm), respectively. The phyllites show relatively high 
Th/U values of 2.3 – 7.8 (average 4.1).  
Comparing to the Post-Archean Australian (average) Shale(PAAS; Taylor and McLenan, 
1985), the phyllites show general enrichment of Zr, Hf, Y, Th and U and depletion of Nb with 
the exception of samples KP7A, KP9A, KP10A, KP11B, KP16A and KP17B which show 
depletion of Y, Th and U relative to the PAAS (Figure 4.9). 
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Figure 4.9 PAAS-normalised patterns for Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana. Data for Post-Archean Australian (average) Shale(PAAS) are from 
Taylor and McLennan (1985). 
 
4.2.2.4 Rare-earth element (REEs) 
The REE data for the phyllites are somewhat variable with total REE (∑REE) values of 88.61-
533.21 ppm averaging of 191.26 ppm which is relatively higher than that of the Post-Archean 
Australian (average) Shale (PAAS; ∑REE, average = 184.8 ppm; Taylor and McLennan, 
1985). The REE data for the phyllites display a single trend based on curve which is similar to 
the trend of the Post-Archean Australian (average) Shale (Figure 4.10). The phyllites show 
light rare-earth element (LREE) enrichment relative to the heavy rare-earth elements (HREE) 
and LaN/YbN values of 4.07-9.78 with an average of 7.56 (except for sample KP17B which 
shows extremely high LaN/YbN value of 100.31). The phyllites also exhibit LREE enrichment 
(LaN/SmN) of 0.86-6.41 (average 3.78), low GdN/YbN values of 0.91-1.77 (average 1.46), 
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except for sample KP17B which has GdN/YbN value of 6.41. They also show Eu anomalies 
[(Eu/Eu* = Eu ½N/(SmN*GdN) ; where N refers to normalised values] of 0.46-0.77 (average 
0.61).  
In comparison with the Post-Archean Australian (average) Shale(PAAS; Taylor and 
McLennan, 1985), the phyllites show a general enrichment of REEs except for samples KP4A, 
KP5A, KP6A, KP9A, KP10A, KP12A and KP13A which have average to below average REE 
concentrations compared to the PAAS (Figure 4.11). 
 
 
 
Figure 4.10 Chondrite-normalized REE patterns in Neoproterozoic phyllites from the 
Akuapim range, southeastern Ghana. Normalizing values are from Boynton (1984). Post-
Archean Australian (average) Shale(PAAS) is plotted for comparison (values are from Taylor 
and McLennan, 1985). 
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Figure 4.11 PAAS-normalized REE patterns in Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana. Post-Archean Australian (average) Shale (PAAS) values are from 
Taylor and McLennan (1985). 
 
4.2.3 Role of Metamorphism 
In general, rocks of the Togo Structural unit have undergone low-grade metamorphism (Kesse, 
1985). The phyllites show greenschist minerals such as chlorite which is indicative of low-
grade metamorphism (Table 4.1). Siderite in the sediments may suggest that the rocks have 
undergone a low-grade metamorphism as siderite is extremely unstable and undergoes 
secondary alterations during high-grade metamorphism (Table 4.1; Kholodov and Butuzowa, 
2008). Additionally, the major, trace, and rare-earth element concentrations of the sphyllites 
show little variation suggesting that metamorphism did not greatly affect their chemical 
composition. 
 
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4.3 GEOCHEMICAL CLASSIFICATION OF THE ROCKS  
Various workers have classified sedimentary rocks based on their chemical composition using 
various classification schemes (Crook, 1974; Petijohn et al., 1972; Blatt et al., 1980; Herron, 
1988). Even though the classification schemes were initially proposed for sedimentary rocks, 
their application to metasedimentary rocks have gained attention in recent studies (Dampare, 
2004; Roddaz et al., 2007; Manu et al., 2013).  
The phyllites were also classified using the geochemical classification of Herron (1988), the 
plot of Fe2O3-K2O and SiO2-Al2O3 ratio. On the Fe2O3/K2O versus SiO2/Al2O3 diagram 
(Figure 4.12; after Herron, 1988), the Neoproterozoic phyllites from the Akuapim range are 
classified as mostly arkose and shale with minor wacke, subarkose, sublitharenite and 
litharenite. However, the regions within which these phyllites plot are probably due to the bulk-
geochemical analyses of the samples which do not depict the various detrital components of 
the rocks.  
Geochemical classification proposed by Crook (1974), which employs the Na2O and K2O 
contents was also used to classify the geochemical characteristics of the phyllites. On this 
diagram (Figure 4.13; after Crook, 1974), the data for the Neoproterozoic phyllites plot 
predominantly in the quartz-rich field with few straddling the quartz-intermediate field. 
Additionally, the phyllites have high SiO2 contents (average = 75.14 wt%) typical of quartz-
rich sediments (SiO2 contents > 65 wt%; Crook, 1974). This sugests that the sediments are rich 
in quartz indicating that the sediments are derived from old/recycled sedimentary sources.  
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Figure 4.12 Chemical classification of Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (fields after Herron, 1988). 
 
 
Figure 4.13 Major element chemical classification of the Neoproterozoic phyllites from the 
Akuapim range, southeastern Ghana (after Crook, 1974). 
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4.4 MINERAL CONTROLS ON MAJOR AND TRACE ELEMENT DISTRIBUTION 
SiO2 shows a strong negative linear trend with the other major elements (Figure 4.14) which 
may suggest greater quartz content and a smaller proportion of detrital grains (Rollinson, 
1993). SiO2 content also exhibits a strong negative correlation with Al2O3 (linear correlation 
coefficient, r = -0.92) showing that much of SiO2 is present as quartz grains. Aluminium 
concentration is a reasonably good measure of detrital flux (Nagarajan, 2007), and therefore 
the positive correlations between Al2O3 and TiO2, MgO, Na2O, and K2O suggest that these 
elements are associated entirely with detrital phases such as clay minerals and micas (Dabard, 
1990; Condie et al., 1992). Al2O3 also shows positive correlations with Sc, V, Cr, Rb, Sr, Rb, 
Cs, Ba, Y, Nb, Ta, Th and U (Table 4.3) suggesting that these elements are associated with 
clay minerals and/or micas. Moderate correlation between Al2O3 and Fe2O3 + MgO and total 
REE infers that Fe, Mg and REE (Table 4.3) are partly controlled by phyllosilicates.  
The K2O contents of the phyllites show a strong positive correlation with Al2O3, Ba, Cs, Rb, 
Th, U, Ta, Nb and Ba (Table 4.3). This suggests that these elements are controlled by clay 
minerals and/or mica (McLennan et al., 1983). K2O makes up about 5-10% by weight of most 
illite (Deer et al., 1966) and therefore, these elements are probably controlled by illite identified 
in the sediments. K2O shows moderate correlation with total REE indicating that the REEs are 
partly controlled by clay minerals and mica. A negative correlation exists between Zr and total 
REE which reveals that the REE are hosted in mica (Condie et al., 1992). Th shows positive 
but low correlation with total REE which may indicate that REE is partly controlled by allanite-
monazite (Condie et al., 1992).  
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According to Roddaz et al., (2007), P2O5 contents in sediments are usually associated with 
accessory phases such as apatite and monazite. Therefore, the moderate correlation between 
P2O5 and Cs, Ni and Co suggests that these elements are partly controlled by accessory 
minerals such as apatite and monazite. In general, the large ion lithophile elements (e.g, Rb, 
Cs, Th, U), high field strength elements (e.g., Zr, Nb, Hf), ferromagnesian elements (e.g., Sc, 
V, Cr) as well as REE show strong interrelationships. This indicates the chemical coherence 
and uniformity of the phyllites. Strong correlation between Zr and Hf and Nb and Ta suggest 
that these elements are mainly concentrated in stable heavy minerals (Roddaz et al., 2007). Ni 
and Co show moderate correlation with Al2O3 but strong correlation with Cr, Ni and V which 
shows that Co and Sc are concentrated in oxides and other accessory non-aluminous silicate 
minerals (Asiedu et al., 2000). 
 
Figure 4.14 Binary plots of SiO2 versus other major elements for the Neoproterozoic phyllites 
from the Akuapim range, southeastern Ghana. 
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Figure 4.15 Binary plots of Al2O3 versus other major elements for the Neoproterozoic phyllites 
from the Akuapim range, southeastern Ghana. 
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Table 4.3 Linear correlation coefficients for selected elements 
Elements Linear correlation 
K2O-Al2O3 0.85 
K2O – Ba 0.86 
K2O – Cs 0.65 
K2O – Rb 0.87 
K2O – Th 0.77 
K2O – U 0.87 
K2O – Ta 0.8 
K2O – Nb 0.87 
K2O – Ba 0.86 
K2O-total REE 0.19 
Al2O3-Fe2O3 + MgO 0.49 
Al2O3-TiO2 0.98 
P2O5 – Cs 0.55 
P2O5 – Ni 0.68 
P2O5 – Co 0.68 
Th – Cs 0.88 
Th-total REE 0.34 
Al2O3-total REE 0.29 
Zr-total REE -0.32 
La-Al2O3 0.24 
Yb – Zr 0.31 
Yb-Al2O3 0.9 
La – Zr -0.35 
Zr-Eu/Eu* 0.1 
Fe2O3-Al2O3 0.46 
Sc-Al2O3 0.96 
V-Al2O3 0.94 
Cr-Al2O3 0.93 
Ni-Al2O3 0.3 
Co-Al2O3 0.26 
Cu-Al2O3 0.37 
Rb-Al2O3 0.97 
Sr-Al2O3 0.58 
Cs-Al2O3 0.86 
Ba-Al2O3 0.78 
Y-Al2O3 0.84 
Nb-Al2O3 0.98 
Ta-Al2O3 0.98 
Th-Al2O3 0.97 
U-Al2O3 0.84 
Cr – Ni 0.23 
Cr – Co 0.23 
Ni – Co 0.8 
Zr – Hf 0.99 
Ta – Nb 0.98 
Nb – Th 0.97 
Nb – U 0.88 
Th – U 0.79 
 
 
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CHAPTER FIVE 
DISCUSSION 
5.1 IMPLICATION OF MINERALOGICAL CONTENT 
According to Armstrong-Altrin et al (2004), increasing compositional maturity of clastic 
sediments leads to an increase in the quartz content with respect to clay-size materials. This is 
because the transport of sediments usually leads to the removal of less stable minerals such as 
clay minerals and the enrichment of more stable minerals such as quartz. The phyllites have 
relatively high quartz content of 30-49 wt% and low content of clay size materials such as 
chlorite and muscovite (average = 17.2 wt%; 17.8 wt%, respectively) suggesting 
compositional maturity of sediments.  
In addition, Bhatia (1985) showed that sediment maturity may be determined by the maturity 
index which is defined as the ratio of total phyllosilicates to phyllosilicates + tectosilicates 
(mainly feldspar and quartz). The phyllites have high quartz/feldspar ratios [average 
(quartz/quartz + feldspar) = 0.71] further confirming the compositional maturity of the 
sediments (Cullers, 2000). The maturity of clastic sediments have been associated with 
sedimentary sorting (Veizer and Jansen, 1979; McLennan, 1989). Therefore, the maturity of 
the sediments may suggest sedimentary sorting of the phyllites probably during transportation 
of sediments.  
The ratios between quartz and feldspar of clastic sediments have been shown to give useful 
clues on the source rock composition (Cullers, 2000). According to Cullers (2000), high ratios 
between quartz and feldspar is indicative of a probable sediment production by weathering of 
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crystalline rocks and/or by recycling of sedimentary deposits. The phyllites exhibit high 
quartz/feldspar ratios (average = 2.61) which suggest derivation of sediments from crystalline 
rocks and/or recycled sedimentary rocks.  
The relative quartz, feldspar and phyllosilicate proportions in fine-grained sediments is 
indicative of their tectonic setting (Bhatia, 1985). According to Bhatia (1985), oceanic island 
arc rocks are characterised by high feldspar and low phyllosilicate content. They are derived 
from calc-alkaline andesitic mudrocks of magmatic arcs. Again, mudrocks of the continental 
island arc and active continental margins (Andean type and strike-slip basins) are characterised 
by a higher phyllosilicate content. Passive margin mudrocks are characterised by extremely 
high phyllosilicate and low feldspar contents, suggesting their recycled nature. The analysed 
phyllites have relatively low feldspar content (average = 14.6 wt%) and relatively high quartz 
content (average = 35.5 wt%) which are characteristic of sediments derived from passive 
margin tectonic setting. 
Furthermore, the maturity of sediments has been related to the tectonic setting of siliciclastic 
sedimentary rocks (Roser and Korsch, 1986). The high proportion of quartz and compositional 
maturity of the sediments indicate that the source rocks were probably exposed to prolonged 
weathering conditions. A passive continental margin is the most probable geotectonic setting 
for the source rocks as it allows for the exposure of sediments to long episodes of weathering 
due to slow input of sediments and less tectonic activity. The long episode of weathering leads 
to the removal of less stable minerals and subsequent enrichment in more stable minerals such 
as quartz. The maturity of the Neoproterozoic phyllites suggest a passive continental margin 
geotectonic setting for the source rocks (Roser and Korsch, 1986).  
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5.2 SEDIMENTARY SORTING AND RECYCLING 
Sorting is one of the most important sedimentary processes from which the energy and type of 
medium of transport, distance, duration of transport and tectonics of the source area can be 
deduced (Kuenen, 1955; 1956). Sorting is generally determined by analysing the textural 
maturity, grain sizes and shapes and mineralogical composition of sedimentary rocks 
(McLennan et al., 1993). However, chemical composition of sedimentary and 
metasedimentary rocks may be used to evaluate sedimentary sorting (McLennan et al., 1993; 
Kasanzu et al., 2008). Sedimentary sorting is usually inferred from the compositional maturity 
which is determined by the relative concentrations of major elements in sediments. This is 
based on the mobility of major elements during sedimentary processes such as sorting, and 
therefore, the effect of this process can be determined by the relative concentration of major 
elements that remain in the sediments. Sedimentary sorting usually leads to the destruction and 
removal of less stable elements (e.g., plagioclase) and subsequent enrichment of more stable 
elements (e.g., quartz).  
The phyllites have SiO2 concentrations (average = 75.14 wt%) which are relatively higher than 
that of the average Upper Continental Crust (UCC, SiO2 = 66 wt%; Taylor and McLennan, 
1985) and Post-Archean Australian (average) Shale(PAAS, SiO2 = 64.8 wt%; Taylor and 
McLennan, 1985). The high SiO2 concentrations is indicative of sediment maturity probably 
due to sedimentary sorting and/or sedimentary recycling as a result of progressive weathering 
which led to the removal of plagioclase, alkali and alkaline earth elements and enrichment of 
more stable components (McLennan, 1989). Also, the phyllites show high SiO2/Al2O3 values 
(average = 8.17) supporting sediment maturity and therefore, sedimentary sorting (Pettijohn et 
al., 1972; Armstrong-Altrin et al., 2004).  
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Various minerals have different stabilities under surface conditions (Goldich, 1938). 
Potassium (K) feldspar is more stable under surface conditions and environments than sodium 
(Na) plagioclase. As a result, the relative proportion of these minerals in sediments may also 
be used to deduce the maturity and degree of sorting of sedimentary and metasedimentary 
rocks. The relative proportion of K-feldspar and Na-plagioclase is given by the K2O/Na2O 
ratio (Bhatia, 1985). The phyllites exhibit high K2O/Na2O values (average = 54.31) indicative 
of high K-feldspar content and low Na-plagioclase which suggest that the sediments are mature 
and highly sorted. The bivariate plot of SiO2 against total Al2O3+K2O+Na2O proposed by 
Suttner and Dutta (1986) can be used to identify the maturity of the phyllites as a function of 
climate. On this plot (Figure 5.1), the phyllites plot in a trend indicating increasing chemical 
maturity of sediments in semi-arid to semi-humid region. The chemical maturity supports the 
interpretation of sedimentary sorting of the sediments. 
Geochemical studies by various workers such as McLennan et al. (1993) and Akarish and El-
Gohary (2008) have shown that the degree of sedimentary sorting may be inferred from the 
accumulation of heavy minerals especially zircon (McLennan et al., 1993; Akarish and El-
Gohary, 2008). Zircon is relatively stable and more resistant during sedimentary processes 
such as sorting, weathering and becomes relatively enriched in highly sorted sediments 
(McLennan, 1989). Zirconium (Zr) is a predominant constituent of zircon (ZrSiO2), therefore, 
the geochemical characteristics of zirconium can be used to evaluate the degree of sorting in 
clastic sediments. The phyllites show high concentrations of Zr (range = 184-719 ppm, average 
= 408.08 pp) indicating enrichment in zircon which suggest sedimentary sorting. 
 
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Figure 5.1 Bivariate plot of SiO2 versus Al2O3+ K2O + Na2O for the Neoproterozoic phyllites 
from the Akuapim range, southeastern Ghana (after Suttner and Dutta, 1986). 
 
Sedimentary recycling usually leads to high degree of sorting in clastic sediments (e.g., Veizer 
and Jansen, 1979; Johnsson, 1993) and it results in changes in the major element composition 
of sediments as recycled minerals have differing susceptibilities to weathering and alteration 
(Cox and Lowe, 1995b). As a result, K2O tend to be enriched in recycled sediments (Potter et 
al., 1975; Potter et al., 1980; Cox and Lowe, 1995b). The phyllites show enrichment of K2O 
(average = 3.90) as compared to that of the average Upper Continental Crust (UCC, 3.39; 
Taylor and McLennan, 1985) which may suggest sedimentary recycling.  
However, Cox and Lowe (1995b) suggested that high concentrations of K2O may also be 
related to first-cycle, feldspar bearing mudrocks which are rich in potassium. The recycled 
sediments may be distinguished from the first-cycle, feldspar bearing sediments by their 
relative proportion of potassium and alumina which is given by the K2O/Al2O3 ratio (Cox and 
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Lowe, 1995b). First-cycle, feldspar bearing mudrocks have K2O/Al2O3 values greater than 0.4 
whereas recycled mudrocks have values less than 0.3 (Cox, 1993). The phyllites generally 
show K2O/Al2O3 values between 0.2 and 0.37 with an average of 0.3 which are within the 
range for recycled mudrocks confirming sedimentary recycling. 
The plot of Th/Sc against Zr/Sc proposed by McLennan et al. (1993) can be used to depict the 
direct correlation between Zr enrichment in sediments and sedimentary recycling. On the plot 
of Th/Sc versus Zr/Sc (Figure 5.2), the phyllites plot in a region and in a trend which support 
zircon addition revealing the relative Zr enrichment and sedimentary sorting. This plot 
supports that the sediments were probably derived from recycled sediments of felsic 
composition. 
Rare-earth element (REEs) are generally immobile but they also exhibit gradation in aqueous 
solubility as the heavy REE (HREE) form soluble complexes more easily than the light REE 
(LREE) (Brookins, 1989). As a result, sedimentary recycling will lead to an increase in the 
light relative to the heavy REE (LREE/HREE) (Cox and Lowe, 1995b). The phyllites show 
LREE enrichment relative to the HREE (average LaN/YbN = 1.46) confirming sedimentary 
recycling. 
 
 
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Figure 5.2 Plot of Th/Sc versus Zr/Sc for the Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana (after McLennan et al., 1993). Values for felsic, andesites and 
basalts are from Condie (1993). 
 
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5.3 PROVENANCE 
5.3.1 Source-area weathering and diagenesis 
The major element composition of sedimentary and metasedimentary rocks reflects their 
mineralogy, which is sensitive to chemical weathering (Harris and Adams, 1966; Middleburg 
et al., 1988). Chemical signatures imparted upon the sediments by chemical weathering may 
be transferred to the sedimentary record (e.g., Nesbitt and Young, 1982; Wronkiewicz and 
Condie, 1987), and therefore provide a useful tool for determining source-area weathering 
conditions. Chemical weathering generally leads to the depletion of alkalis (e.g., Na) and 
alkaline earth elements (e.g., Ca) and preferential enrichment of SiO2 and A12O3 (Cox et al., 
1995).  
The phyllites show relative depletion of Na2O and CaO (average = 0.14 wt%, 0.02 wt%, 
respectively) and enrichment of SiO2 and A12O3 (average = 75.14 wt%; 13.25 wt%) indicative 
of the depletion of alkalis and alkaline earth elements suggesting high chemical weathering in 
the phyllites. Additionally, compositionally more complex clays such as smectites and 
chlorites, which contain Ca, Na, Fe, and Mn, degrade quickly during weathering as compared 
to illite containing K2O which is stable and resistant to weathering (Cox et al., 1995). 
Therefore, the relationship between these major elements may be used to infer the chemical 
weathering of sediments (Nesbitt and Young, 1982). The phyllites have relatively high 
K2O/Na2O (range = 8.93-113.67, average = 54.31) which support a high intensity of chemical 
weathering at the source area.  
The intensity of chemical weathering of sedimentary and metasedimentary rocks can be 
quantified using indices proposed by various workers (Nesbitt and Young, 1982; Harnois, 
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1988; Cox et al., 1995; Fedo et al., 1995). One of these indices is the chemical index of 
alteration (CIA) which measures the extent of conversion of feldspars (which dominate the 
upper crust) to clays and is defined as (Nesbitt and Young, 1982):  
CIA = [Al2O3/(Al2O3 + CaO* + Na2O + K2O)] × 100; In molecular proportions. Where the 
CaO* refers to CaO in silicates only.  
Ca in carbonates could not be corrected to obtain CaO* due to the lack of CO2 data. But the 
overall low LOI contents suggest that carbonates were rather rare in the analysed sediments 
(Table 4.1). Therefore, CaO concentrations were used as CaO* for the calculation (Bock et al., 
1998). CIA values of 45-55% indicate weak weathering and values of 56-65% indicate 
moderate weathering whereas values greater than 65% indicate intense weathering in the 
source area. Also, CIA values for unweathered terrestrial basalts are in the range of 40 to 50 
whereas for granites the range is 50 to 55 (Fedo et al., 1995). The phyllites have relatively high 
CIA values (average = 74.73 %) which are significantly greater than that of PAAS (70; Taylor 
and McLennan, 1985) and falls within the range for intensive chemical weathering. This 
indicates that the source rocks of these sediments may have been subjected to intense 
weathering conditions under a warm humid climate, for a shorter period or moderate degree 
of chemical weathering for an extended period of time.  
During diagenesis, K-metasomatsism (i.e, illitisation of smectite and/or plagioclase 
albitization) leads to the addition of post-depositional potassium (K) to older clastic rocks 
(Fedo et al., 1995). This limits the use of the chemical index of alteration parameter which 
does not correct for this effect. Accordingly, K-free indices such as plagioclase index of 
alteration (PIA) and the chemical index of weathering (CIW) have been calculated to 
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determine the intensity of chemical weathering for the phyllites. Plagioclase Index of 
Alteration (PIA) is defined as:  
PIA = 100 x [(Al2O3-K2O)/(Al2O3+CaO*+Na2O-K2O)] (after Fedo et l., 1995); and 
Chemical index of weathering (CIW) is defined as: 
CIW = [Al2O3/(Al2O3+CaO∗+Na2O)] x 100 (after Harnois, 1988);  In molecular proportions. 
Where CaO* represents the CaO in silicates only.  
CaO concentrations were used as CaO* for the calculation as explained earlier. High PIA 
values (> 90%) indicate complete conversion of plagioclase into aluminous clay minerals such 
as kaolinite, illite and gibbsite and low PIA values (≤ 50%) indicate unweathered plagioclase 
(Fedo et al., 1995). Also, high CIW values (90-98%) indicate intense weathering at source area 
(Condie, 1993). The phyllites show high PIA (average = 97.68 %) values higher than 90% 
which indicate complete conversion of plagioclase into aluminous clay minerals suggesting 
high intensity of chemical weathering at source area. Additionally, the phyllites exhibit high 
CIW values (range = 96.20-99.28 %; average = 98.36 %) which fall within the range for 
sediments derived from highly weathered source terrains supporting high intensity of chemical 
weathering at the source area.  
The CIA data are plotted on an A-CN-K diagram (Nesbitt and Young, 1982), to give a graphic 
representation which allows for the evaluation of the extent of chemical weathering (Nesbitt 
and Young, 1984). On this plot (Figure 5.3), the phyllites clusters along the A-K edge 
suggesting an intense chemical weathering. According to Barbera et al. (2006), this trend is 
indicative of sediment derivation from crystalline basement rocks subjected to an alteration 
process leading to the significant loss of Na, Ca. The source rock composition can also be 
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determined from this ternary plot by backward extrapolation of the weathered samples, parallel 
to the A-CN line (Fedo et al., 1996). The backward extrapolation of the line from the weathered 
sample points indicates the provenance of the phyllites to be originated from average granite 
(Figure 5.4). 
 
 
 
Figure 5.3 Ternary A-CN-K (Al2O3-CaO+Na2O-K2O) for Neoproterozoic phyllites from the 
Akuapim range, southeastern Ghana (after Nesbitt and Young, 1984; 1989). Average values 
of G: granite; A: andesite; B: basalt; values taken from Condie (1993). Upper Continental 
Crust (UCC) plotted for comparison (values taken from Taylor and McLennan, 1985).  
 
CIA, PIA and CIW indices generally reflect the amount of feldspar and plagioclase relative to 
clay minerals respectively, and therefore are not strongly sensitive to the composition of source 
rock (Potter, 2005). The index of compositional variability (ICV) proposed by Cox et al. (1995) 
was calculated for the phyllites as it includes Fe and Mg which gives a better insight on the 
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source rock composition (Potter, 2005). Index of compositional variability (ICV) measures the 
abundance of alumina relative to the other major cations in the sediments excluding SiO2 and 
therefore eliminating the effect of quartz dilution. ICV is defined by:  
ICV = [CaO+K2O+Na2O+Fe2O3(t)+MgO+MnO+TiO2]/Al2O3;  In weight percents (wt%). 
Where Fe2O3(t) = total iron and CaO includes all sources of Ca.  
In general, ICV values decrease with increasing degree of weathering. ICV values for average 
basalt and average granite are 2.20 and 0.95 respectively (Li, 2000). The phyllites have low 
ICV values (average = 0.64) indicating high intensity of chemical weathering at the source 
area. Also, the low ICV values reflect compositionally mature sediments which describe 
intracratonic environments (Weaver, 1989), where the recycling of old sediments is an active 
process, or provenance from intensely weathered crystalline basements (Barshad, 1966). The 
ICV values of the phyllites are close to that of granite suggesting a probable component of 
provenance of granitic composition. A binary plot of CIA index versus ICV index (after Potter, 
2005), which may provide relevant clues on the source rock composition based on the intensity 
chemical weathering was plotted for the phyllites. On this plot (Figure 5.4), the phyllites 
mostly plot close to the trend for granite composition suggesting a granitic source rock 
composition as inferred from the ICV values. 
Even though trace elements are generally less mobile during chemical weathering, some trace 
elements, such as Ba and Sr may be efficiently removed from soils (Wedepohl, 1978). During 
chemical weathering, Rb is preferentially incorporated into clays and divalent Sr undergoes 
leaching leading to the relative high concentrations of Rb and low Sr concentrations in 
sediments (Camiré et al., 1993). As a result, the Rb/Sr values of sediments may infer the degree 
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of source area weathering (McLennan et al., 1983). The phyllites have high Rb/Sr values 
(average = 4.22) which are significantly higher than that of UCC (0.32; Taylor and McLennan, 
1985) and PAAS (0.88; Taylor and McLennan, 1985) suggesting high intensity of chemical 
weathering at the source area.  
 
 
 
Figure 5.4 Plot of CIA index versus ICV index for the Neoproterozoic phyllites from the 
Akuapim range, southeastern Ghana (after Potter, 2005). 
 
Also, McLennan et al. (1993) showed that intensive chemical weathering leads to the elevation 
of Th/U due to the oxidation of U4+ to U6+, decreasing the abundance of U in sediments and 
therefore resulting in Th/U ratios higher than those of upper crustal igneous rocks (about 3.5-
4.0, McLennan et al., 1993). The phyllites have high Th/U values (average = 4.09) higher than 
those of upper crustal igneous rocks suggesting high intensity of chemical weathering. 
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Additionally, on a plot of Th/U versus Th (Figure 5.5; after McLennan et al., 1993), the 
phyllites plot in a trend indicative of recycled sediments which might have undergone some 
degree of weathering. 
 
 
 
Figure 5.5 Plot of Th/U versus Th for Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (after McLennan et al., 1993). 
 
The effect of diagenesis in the phyllites may be inferred from the geochemical modifications 
to major element (such as K2O) composition of the sediments (Wintsch and Kvale, 1994). The 
phyllites have high K2O concentrations (average = 3.90 wt%) which are slightly lower than 
that of Post-Archean Australian (average) Shale(PAAS: 3.97 wt%; Taylor and McLennan, 
1985). This may suggest that the sediments have not undergone significant post-depositional 
K-metasomatism (Roddaz et al., 2007). The A-CN-K diagram may be used to infer the effect 
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of post-depositional K-metasomatism in sediments (Fedo et al., 1997). According to Fedo et 
al. (1997), trends resulting from the chemical weathering of crystalline bedrock are roughly 
parallel to the A-CN boundary; however, K-metasomatism may result in significant departure 
from the predicted weathering trend. On this diagram (Figure 5.3), the analysed phyllites data 
plot along the A-K line instead of A-CN line. This type of trend shown in the A-CN-K diagram 
indicate that the phyllites have not undergone K-metasomatism supporting the interpretation 
by the low K2O content relative to PAAS.  
 
5.3.2 Source rock composition 
Geochemical studies have shown that the chemical composition of sedimentary and 
metasedimentary rocks generally reflect the provenance of their detrital source rocks (Roser 
and Korsch, 1986; McLennan et al., 1993). These studies are based on the direct correlation 
between the chemical composition of sedimentary and metasedimentary rocks expressed as 
abundances of certain major or trace elements or ratios of elemental abundances and their 
source rock composition (McLennan et al., 1993).  
The phyllites have high SiO2 concentrations (average = 75.14 wt%) suggesting derivation of 
sediments from a granitic source or acidic high-grade metamorphic rocks (Crook, 1974). 
According to Cox et al. (1995), sediments derived by weathering of progressively more 
granitic source materials have high concentrations of Al2O3 and K2O. The phyllites show 
relatively high concentrations of Al2O3 and K2O (average = 13.25 wt%, 3.9 wt%) which 
support the interpretation that they were probably derived from granitic/felsic source rocks 
(Cox et al., 1995).  
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The ratio of TiO2 and Al2O3 in sediments have been used to infer their source rock composition 
(Hayashi et al., 1997; Nagarajan, 2007). TiO2 is relatively enriched in mafic rocks than in felsic 
rocks and Al2O3 which resides in feldspars is relatively enriched in more felsic/granitic source 
rock. Al2O3/TiO2 ratios increases from 3 to 8 for mafic igneous rocks, from 8 to 21 for 
intermediate rocks, and from 21 to 70 for felsic igneous rocks (Hayashi et al., 1997). The 
phyllites have high Al2O3/TiO2 values (average = 21.87) characteristic of sediments derived 
from felsic source rocks.  
The plot of K2O versus Rb proposed by Floyd and Leveridge (1987) can be used to distinguish 
sediments of acid to intermediate rock composition from those derived from basic 
composition. On this plot (Figure 5.6), all the phyllites plot close to the typical differentiated 
magmatic suite with ratio of 230 (Shaw, 1968) and fall within the acid to intermediate 
composition range suggesting that the sediments were probably derived from magmatic rocks, 
predominantly acidic to intermediate in composition.  
In addition, on a ternary diagram of SiO2/20-K2O+Na2O-MgO+FeO+TiO2 (Figure 5.7) 
proposed by (Roser and Korsch, 1988), majority of the phyllites plot near rhyolite with few 
plotting near dacite, andesite and basalt regions suggesting a major component of provenance 
of felsic composition.  
Discriminant function diagram of Roser and Korsch (1988) is another method that can be used 
to further constrain the source rock composition of the phyllites. The discriminant functions 
of Roser and Korsch (1988) discriminate between four sedimentary provenance fields. These 
are: mafic igneous provenance (P1)-first cycle basaltic and lesser andesitic detritus; 
intermediate igneous provenance (P2)-dominantly andesitic detritus; felsic igneous 
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provenance (P3)-acid plutonic and volcanic detritus; and quartzose sedimentary 
provenance/recycled (P4)-mature polycyclic quartzose detritus (indicate sedimentary 
maturity). On this diagram (Figure 5.8), the phyllites plot in the P4 field, supporting derivation 
of mature sediments from recycled sedimentary sources, similar to passive margin-derived 
sediments (Roser and Korsh, 1988).  
 
 
Figure 5.6 Distribution of K2O and Rb in the Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana, relative to a K2O-Rb ratio of 230 (values for K2O-Rb ratio are from 
Shaw, 1968) (after Floyd and Leveridge, 1987). 
 
 
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Figure 5.7 A ternary plot of SiO2/20-K2O+Na2O-MgO+Fe*+TiO2 for the Neoproterozoic 
phyllites from the akuapim range. Southeastern Ghana (after Roser and Korsch, 1988). 
 
 
Figure 5.8 Discriminant function diagram for Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana (after Roser and Korsch, 1988).  
 
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Source rock composition of sedimentary and metasedimentary rocks is best determined using 
trace elements, especially the immobile elements, such as REE, Th, Cr, Co, Zr, and Y. This is 
because their distribution is not significantly affected by sedimentary processes, diagenesis 
and metamorphism (Taylor and McLennan, 1985; Wronkiewicz and Condie, 1987; 
McLennan, 1989; Cox et al., 1995). Trace elements are generally concentrated in clay minerals 
as sorbed particles on surfaces or included in interlayer cation sites, and are transferred nearly 
quantitatively and unfractionated into the sedimentary record during sedimentary processes 
(Goldberg, 1954; Ermolenko, 1972; Roaldset, 1973, 1978; Davies, 1980; Salomons and 
Forstner, 1984; Taylor and McLennan, 1985; Horowitz and Elrick, 1987; McLennan, 1989; 
McBride, 1991; Horowitz, 1991; Keizer and Bruggenwert, 1991; Cox and Lowe, 1995). As a 
result, their abundance in sedimentary and metasedimentary rocks generally reflect the 
composition of their source rocks (Cullers et al., 1975; Taylor and McLennan, 1985; 
McLennan, 1989; Asiedu et al., 2004; Manu et al., 2013). 
Trace elements usually occur as sorbed particles on the surfaces of clay minerals (Goldberg, 
1954; Ermolenko, 1972; Roaldset, 1973, 1978; Davies, 1980). The geochemical characteristics 
of the phyllites show strong correlations between Sc, V, Cr, Rb, Cs, Ba, Y, Nb, Ta, Th, U and 
Al2O3 (linear correlation coefficient, r = 0.97, 0.94, 0.93. 0.97, 0.86, 0.78, 0.85, 0.98, 0.98, 
0.97, 0.84, respectively) indicating that these elements are hosted in clay minerals and their 
chemical signatures can be used to infer the source rock composition of the sediments.  
The transition metals (e.g., Cr, Co, Ni, V and Sc) behave similarly during magmatic processes 
(Feng and Kerrich, 1990), and are usually enriched in mafic and ultramafic igneous rocks 
(Bock et al., 1998). The transition elements are more concentrated in mafic rocks due to the 
much smaller size of their ions allowing them to enter early crystallizing minerals (Taylor and 
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McLennan, 1985). As a result, the relative abundance of transition metals in sediments may 
provide important clues about their source rock compositions. In general, the phyllites show 
low concentrations of Cr, Ni, V and Sc with slight enrichment of Co compared to the Post-
Archean Australian (average) Shale (PAAS) (Figure 4.9). This suggests that very minimal 
mafic rocks were exposed in the source area suggesting a felsic provenance (Wrafter and 
Graham, 1989). The slight enrichment of Co is probably be due to post-depositional alterations 
in the sediments (Osae et al., 2006).  
According to Feng and Kerrich (1990), high field strength elements (HFSE) such as Zr, Nb, 
Hf, Ta, Y, Th and U are preferentially incorporated into melts during crystallization and 
anatexis and therefore, these elements are enriched in felsic rather than mafic rocks. The 
phyllites show relatively high concentrations of Zr, Y, Hf and Th as compared to the Post-
Archean Australian (average) Shale (PAAS) (Figure 4.12), suggesting felsic source rock 
composition for the sediments.  
Studies by McLennan and Taylor (1991) have shown that Th/U ratios serves as a good 
indicator of provenance of sediments. According to McLennan and Taylor (1991), sediments 
derived from oceanic island arcs and oceanic basalts have low Th/U ratios. The phyllites have 
relatively high Th/U (average = 4.09) values which suggest no or low input of sediments of 
basaltic composition supporting felsic provenance for the sediments. 
In addition, the relative distribution of immobile elements such as La and Th in felsic and basic 
rocks may be used to infer the relative contribution of felsic and basic sources in sediments 
from different source rock terranes (Wronkiewicz and Condie, 1990). According to Floyd and 
Leveridge (1987), low and uniform La/Th ratios of less than 5 and Hf abundances of about 3-
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7 ppm are characteristic of sediments derived from felsic composition-dominated arcs. The 
phyllites reveal La/Th values averaging 3.82 which is considerably less than 5 which shows 
derivation of sediments from felsic composition-dominated arcs. The phyllites also show Hf 
(average = 10.52) abundances which are close to the ranges proposed by Floyd and Leveridge 
(1987) for sediments derived from felsic composition-dominated arcs.   
The Cr/Th ratio has been used to discriminate basic sediments from felsic sediments 
(McLennan et al., 1993; Cullers, 1994a, 1994b; Roddaz et al., 2005, 2006). According to 
Cullers (2000), sediments derived from silicic sources have Cr/Th ratios ranging from 0 to 15 
whereas sediments of basic origin have higher Cr/Th ratios that ranges from 22 to 500.  The 
phyllites have Cr/Th (average = 3.73) values which are significantly lower than that of PAAS 
(7.5; Taylor and McLennan, 1985) and fall within the range for felsic sediments (Cullers, 
2000), indicating a significant contribution of felsic component. 
Numerous workers have shown that discrimination diagrams of trace elements may also be 
used to deduce source rock compositions of clastic sediments (e.g., Bhatia, 1983; Taylor and 
McLennan, 1985; Bhatia and Crook, 1986; Jahn and Condie, 1995; Bracciali et al., 2007). The 
plot of Th/Co vs. La/Sc has been used to distinguish between sediments derived from felsic 
rocks and those from basic rocks. On this diagram (Figure 5.9; after Cullers, 2002), the 
phyllites plot close to felsic rocks which shows derivation of sediments from felsic source 
rocks. Also, on a ternary plot of V-Ni-Th*10 (Figure 5.10; after Bracciali et al., 2007), the 
phyllites mainly plot within and close to felsic rocks supporting the interpretation that the 
sediments were derived from felsic source rocks. 
 
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Figure 5.9 Th/Co versus La/Sc for the Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (fields are after Cullers, 2000). 
 
Various workers have shown that the ternary diagrams of Th-Hf-Co and La-Th-Co are very 
important in deducing the source rock composition of clastic sediments (Bhatia, 1983; Taylor 
and McLennan, 1985; Bhatia and Crook, 1986; Jahn and Condie, 1995). On the ternary 
diagram of Th-Hf-Co (Figure 5.11a), the phyllites plot close to continental crust and far from 
average oceanic crust composition, indicating derivation of sediments from a felsic source 
rock. Also, on the plot ternary plot of La-Th-Sc (Figure 5.11b), the samples plot in a trend 
showing abundances of La, Th and Sc similar to that of granite and granodiorite, which 
suggests a felsic source rock composition for the sediments. Cr/Th and Th/Sc ratios are very 
useful tools in constraining the composition of sediment sources (Taylor and McLennan, 1985; 
McLennan et al., 1993; Cullers, 2000). The plot of Cr/Th versus Th/Sc (Figure 5.12) shows 
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that the phyllites cluster close to the felsic volcanics further supporting the interpretation that 
the sediments were derived from felsic source rocks. 
 
Figure 5.10 A ternary plot of V-Ni-Th*10 for Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana (fields are after Bracciali et al., 2007). 
 
In Figure 5.14, plot of La/Th versus Hf (after Floyd and Leveridge, 1987), the phyllites plot 
around the felsic source region and in a trend of increasing old sediment component close to 
the passive margin source. This may be characteristic of mature sediments derived from 
old/recycled sedimentary sources. Furthermore, the ratio Th/Sc probably best reflects the 
overall bulk composition of provenance, therefore making Th/Sc ratio a very important tool in 
deducing source rock compositions (Taylor and McLennan 1985). In Figure 5.2a, the plot of 
Th/Sc versus Zr/Sc (after McLennan et al., 1993), the phyllites cluster close to average granite 
and in a trend characteristic of recycled sediments. This may suggest derivation of sediments 
from recycled sedimentary rocks. 
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Figure 5.11 (a) Th-Hf-Co ternary diagram and (b) La-Th-Sc ternary diagram, for 
Neoproterozoic phyllites from the Akuapim range, southeastern Ghana (compositional fields 
are after Roddaz et al., 2007). Post-Archean Australian (average) Shale(PAAS) and Upper 
Continental Crust (UCC) are plotted for comparison (values are from Condie, 1993).  
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Figure 5.12 A plot of Cr/Th versus Th/Sc for the distribution of Neoproterozoic phyllites from 
Akuapim range, southeastern Ghana. Values for FVO: felsic volcanics; AND: andesites; BAS: 
basalts are from Condie (1993).  
 
 
Figure 5.13 A plot of La/Th versus Hf for Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (compositional fields are after Floyd and Leveridge, 1987). 
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The ratios of Th/Sc, Th/Co, Th/Cr, Cr/Th, and La/Sc ratios are significantly different in felsic 
and basic rocks and may allow constraints on the average provenance composition 
(Wronkiewicz and Condie, 1990; Cox et al., 1995; Cullers, 1995, 2000; Armstrong-Altrin et 
al., 2004). The elemental ratios deduced from composition of the phyllites have been compared 
with those sediments derived from felsic and basic rocks (fine fraction) as well as to Upper 
Continental Crust (UCC) and Post-Archean Australian (average) Shale (PAAS) values (Table 
5.1).  
From Table 5.1, the Neoproterozoic phyllites from the Akuapim range of the Togo Structural 
Unit show elemental ratios which are close to or within the range of sediments derived from 
felsic source rock further confirming provenance of felsic composition.  
 
Table 5.1 Range of elemental ratios of Togo Phyllite compared to the ratios in similar fractions 
derived from felsic rocks, mafic rocks, Upper Continental Crust, (UCC) and Post-Archean 
Australian (average) Shale (PAAS) 
 
Elemental ratios Togo Phyllite Range of sediments UCC PAAS 
  Felsic rocks Mafic rocks  
Th/Sc 0.89-1.58 0.84-20.5 0.05-0.22 0.79 0.9 
Th/Co 0.67-19.85 0.67-19.4 0.04-1.4 0.63 0.63 
Th/Cr 0.20-0.36 0.13-2.7 0.02-0.05 0.13 0.13 
Cr/Th 2.79-4.93 4.00-15.00  25-500 7.76 7.53 
La/Sc 1.93-6.47 2.5-16.3 0.43-0.86 2.21 2.4 
The range of values for sediments from felsic and mafic rock sources are from Cullers et al. 
(1988), Cullers (1994; 2000) and Cullers and Podkovyrov (2000).  
Upper Continental Crust and Post-Archean Australian (average) Shale values are from Taylor 
and McLennan (1985).  
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The enrichment of incompatible elements relative to compatible elements and Eu anomaly of 
the elemental composition provide important information about the source rock composition 
of sediments (Taylor and McLennan, 1985). The light rare-earth elements (LREE) which are 
incompatible elements preferentially go into melt phases during partial melting and therefore 
are relatively enriched in Upper Continental Crust and/or felsic rocks. The heavy rare-earth 
elements (HREE) are preferentially incorporated into the structures of principal minerals 
during magmatic crystallization due to their smaller ionic radius and therefore are enriched in 
mantle and/or basic rocks (Potter, 2005). As a result, the ratio of LREE to the HREE which is 
given by LaN/YbN may be used to distinguish sediments derived from felsic and mafic sources. 
Sediments derived from basic source rocks have low ΣLREE/ΣHREE (LaN/YbN) ratios and 
insignificant Eu anomalies, whereas felsic source rocks usually contain higher 
ΣLREE/ΣHREE (LaN/YbN) ratios (Cullers and Graf, 1984; Cullers, 1994). The phyllites 
exhibit chondite-normalised REE patterns which are similar to that of PAAS (Figure 4.10), 
with a general enrichment of LREE relative to HREE (average LaN/YbN = 7.56) characteristic 
of sediments derived from Upper Continental Crust and/or felsic rocks.  
The anomalous behaviour of Eu is generally inherited from sediment sources and therefore 
makes it an important tool in distinguishing mantle sources from intracrustal sources 
(McLennan et al., 1993; McLennan and Taylor 1991). Sedimentary and metasedimentary 
rocks with negative Eu anomaly are typical of sediments derived from felsic source rocks 
(Cullers, 1994; Gao and Wedepohl, 1995). The phyllites have negative Eu anomalies (average 
Eu/Eu* = 0.61) which are generally close to that of PAAS (0.66; Taylor and McLennan, 1985). 
This is indicative of the present Upper Continental Crust suggesting sediment derivation from 
intracrustal sources, and therefore, felsic source rocks.  
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McLennan et al. (1993, 1995) described five major provenance types on the basis of 
geochemistry, the characteristics of which are summarized in Table 5.2. Comparing the 
geochemical characteristics of the Togo phyllites to that of the major provenances given in 
Table 5.2, the sediments are likely dominated by sources representative of Recycled 
Sedimentary Rocks (RSR). This assertion is supported by the following evidences: 
1) The high heavy mineral concentrations (e.g., Zr, Hf, for zircon, REE for monazite); 
2) The general lack of significant negative Eu anomalies (average Eu/Eu* = 0.61); 
3) Relatively high Th/Sc ratios (average Th/Sc = 1.22); and 
4) In general, phyllites have average to above-average REE abundances with LREE 
enrichment relative to PAAS. 
From the geochemical characteristics, the Togo phyllites were predominantly derived from 
Old/Recycled Upper Continental Crust.  
In an attempt to model the source rock composition for the phyllites, the lithological units 
which are more likely to produce the sediments were considered. These include: Upper 
Continental Crust (UCC), average granites, and tonalite-trondhjenite-granodiorite (TTG). The 
average chemical compositions of Proterozoic Upper Continental Crust, granite and tonalite-
trondhjenite-granodiorite (TTG) from Condie (1993) were used as potential sources for the 
phyllites. The phyllites were modeled using the Fedo et al. (1996) modelling method which 
attempt to conserve mass balance amongst the relatively immobile REEs and in the Th/Sc 
ratios which is a sensitive index of bulk composition (Taylor and McLennan, 1985).  
The model REE values were achieved by following the mass balance equation of Albarède 
(2000): WRmix = αC1 + βC2 +γC3, where WR
mix represents the calculated whole rock 
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compositions, α, β and γ represent the proportion of UCC, granite and TTG obtained from the 
modeling of the source rocks, respectively whereas C1, C2 and C3 represent the rare-earth 
element in UCC, granite and TTG.  
Using the source compositions listed in Table 5.3, average Togo phyllites is composed by a 
mixture of 80% Upper Continental Crust and 20% granite. The modeled chondrite-normalized 
REE patterns for the phyllites are similar to the average phyllites (Figure 5.16) which supports 
the results obtained for the mixing calculations for the source rocks of the Togo phyllites.  
 
 
Figure 5.14 Comparison of Chondrite – normalized REE patterns of average Togo phyllites 
and model Togo phyllites (Parameters are in Table 5.3). 
 
 
 
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Table 5.2 Summary of geochemical characteristics of provenance types 
Terrane Eu/Eu* Th/Sc Other Description 
geochemical 
features 
Old Upper ~0.60- -1.0 Evolved major Old igneous/metamorphic/sedimentary 
Continental 7.0 element terranes affected by intracrustal 
Crust (OUC) composition differentiation. Stable cratons, old 
(e.g., high foundation of active setting. 
Si/Al, CIA); 
High LILE 
abundance; 
uniform 
compositions 
Recycled ~0.60- ≥1.0 Evidence of Recycled sedimentary/metasedimentary 
Sedimentary 0.70 heavy mineral rocks specifically identified. If not separately 
Rocks (RSR) concentrations identified, part of OUC. 
in trace 
elements (e.g., 
Zr, Hf, for 
zircon, REE 
for monazite) 
Young ~1.0 <1.0 Unevolved Young mantle-derived volcanic/plutonic arc 
Undifferentiated major element rocks. Dominates forearcs, components in 
Volcanic Arc compositions continental arcs, back arcs 
(YUA) (e.g., low 
Si/Al, CIA); 
Low LILE 
abundances; 
variable 
compositions 
Young ~0.50- Variable Evolved major Young mantle-derived volcanic/plutonic arc 
Differentiated 0.90 element rocks affected by intracrustal differentiation. 
Volcanic Arc composition Similar environment YUA but more mature 
(YDA) (e.g., high arcs or more discussion. 
 Si/Al, CIA); 
High LILE 
abundances; 
variable 
composition 
 
This Study 0.61 1.22 High Recycled 
Togo Phyllite SiO2/Al2O3 sedimentary/metasedimentary/metamorphic 
and CIA and/or igneous rocks derived from stable 
values. cratons. 
Evidence of 
heavy mineral 
concentrations 
(Zr). 
(after McLennan et al., 1993, 1995) 
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Table 5.3 Results from mixing calculation 
Elements Average Togo Phyllite Mixing end members           Mixing results          
    Upper Continental Crust  Granite   TTG      Model Phyllite          
                  80: 20: 0          
                    Ppm N                     ppm  N       ppm  N     ppm   N                   N 
La 36.87 99.64 30.9 83.51 50 135.14 26 70.27 93.84 
Ce 78.71 82.25 65.3 68.23 95 99.27 45 47.02 74.44 
Nd 33.13 46.59 29.8 41.91 46 64.7 20 28.13 46.47 
Sm 6.1 26.4 5.59 24.2 6.3 27.27 4.5 19.48 24.81 
Eu 1.09 12.5 1.19 13.68 0.85 9.77 1.3 14.94 12.9 
Gd 4.67 15.87 5.24 17.12 4.67 15.26 4.09 13.37 16.75 
Tb 0.65 12.99 0.82 14.14 0.65 11.21 0.63 10.86 13.55 
Yb 3.03 12.21 2.32 9.35 2 8.06 1.5 6.05 9.1 
Lu 0.46 12.17 0.38 9.97 0.32 8.4 0.23 6.04 9.66 
          
(La/Sm)N 3.77  3.45  4.95  3.61 3.75 
(Gd/Yb)N 1.3  1.83  1.89  2.21 1.84 
(La/Yb)N  8.16  8.93  16.76  11.62 10.49 
Eu/Eu*  0.61  0.67  0.48  0.93 0.63 
Th/Sc   1.25   0.72   3.75   0.83 1.32 
N denotes chondrite-normalized value. 
 Values for Upper Continental Crust, Granite and tonalite-trondhjenite-granodiorite (TTG) are from Condie (1993). 
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5.3.3 Tectonic setting of source area 
Geochemistry of clastic rocks have been shown to furnish vital information about the tectonic 
setting of source rocks (Bhatia and Crook, 1986; McLennan et al., 1993). This is based on the 
assumption that different tectonic settings impart characteristic geochemical signatures on 
rocks which are generally retained in the sediments during various sedimentary processes 
(Bhatia, 1983; Dickinson et al., 1983; McLennan et al., 1993;).  
Major element composition of clastic sediments is very useful in the determination of tectonic 
setting of their source areas. According to Crook (1974) greywackes which are quartz-rich (> 
65% quartz) are associated with passive continental margins, quartz-poor greywackes (< 15% 
quartz) are associated with magmatic island arcs and greywackes with intermediate quartz (15-
65% quartz) are indicative of an active continental margin. The phyllites have average SiO2 
concentration of 75.14 wt% which is characteristic of quartz-rich sediments (> 65% quartz) 
which shows derivation of sediments from a passive continental margin. 
Additionally, the major role of sedimentary recycling in the phyllites which is shown by high 
SiO2 and Al2O3 contents and high Th/U ratios may suggest a passive margin tectonic setting 
for the source rock (Veizer and Jansen, 1985). This is supported by the lesser diversity in 
chemical composition of the analysed phyllites which is an expected consequence of sediments 
derived from passive margin tectonic setting (Bhatia 1985; McLennan et al. 1990). 
Studies by Bhatia (1985) showed that ratios of SiO2/Al2O3 and K2O/Na2O increase with 
sandstone and mudstone maturity, which is somewhat due to the change in the dominant source 
rock. This assertion is supported by studies of Roser and Korsch (1986) which showed that the 
SiO2 content and K2O/Na2O ratios of sandstone and mudstone suites can be used to infer their 
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provenance and tectonic setting. Roser and Korsch (1986) proposed three tectonic settings 
based on ancient sandstone-mudstone pairs. The three tectonic settings are passive continental 
margin (PM), active continental margin (ACM) and oceanic island-arc (ARC). On the plot of 
K2O/Na2O versus SiO2 (Figure 5.15), the phyllites predominantly plot in the passive 
continental margin. This supports the interpretation of the compositional maturity of the 
sediments which suggest that the sediments were probably derived from passive margin 
setting.  
In addition, Maynard et al. (1982) used a similar plot of SiO2/Al2O3 versus K2O/ Na2O to 
discriminate different tectonic settings, in their study of modern sediments. On this plot (Figure 
5.16), the phyllites plot mainly in the passive margin setting supporting the derivation of 
sediments from a passive continental margin. 
Immobile trace elements in clastic sediments give very important evidences on the tectonic 
setting of sedimentary and metasedimentary rocks as these elements are transferred 
quantitatively into clastic sediments during weathering and transportation, therefore reflecting 
the signature of their parent material (Armstrong-Altrin et al., 2004).  
According to McLennan and Taylor (1991), Th/Sc values ≥1.0 can be found in most tectonic 
settings where stable crust or recycled sediments are exposed (where the samples plot above 
line = 1). From the plot of Th/Sc versus Sc (Figure 5.17), almost all the phyllites show Sc 
values more than 10 and Th/Sc ratios higher than 1 characteristic of recycled sediments 
deposited on a stable crust.  
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Figure 5.15 K2O/Na2O versus SiO2 diagram for the Neoproterozoic phyllites from Akuapim 
range, southeastern Ghana (fields are after Roser and Korsch, 1986). 
 
Figure 5.16 Plot of SiO2/Al2O3 versus K2O/Na2O for the Neoproterozoic phyllites from 
Akuapim range, southeastern Ghana. Boundary lines for different tectonic settings from Roser 
and Korsch (1986). ACM, active continental margin; PM, passive margin; A1, arc setting, 
basaltic and andesitic detritus; A2, evolved arc setting, felsitic-plutonic detritus. 
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On the plot of La/Y versus Sc/Cr (Figure 5.18; after Bhatia and Crook, 1986) the phyllites plot 
dominantly within passive continental margin with few straddling the active continental 
margin supporting passive margin tectonic setting at the source rock area.  
Additionally, the La-Th-Sc ternary plot (Bhatia and Crook, 1986) shows that arc-derived 
sediments and passive margin sediments can be effectively differentiated from each other. This 
plot successfully discriminates between the different arc settings except for the distinction 
between the active continental margin and passive continental margin. The distinction between 
tectonic settings is based on an increase in the La/Sc ratio as the sands become more mature 
(quartz rich). On the ternary plot of La-Th-Sc (Figure 5.19), the phyllites dominantly plot 
within the continental margin (active and passive) with few straddling the continental island 
arc.  
Th-Co-Zr/10 and Th-Sc-Zr/10 ternary diagrams (Bhatia and Crook, 1986) have been used to 
differentiate between oceanic island arc (OIA), continental island arc (CIA), active continental 
margin (ACM) and passive margin (PM) setting. On the plots of Th-Co-Zr/10 and Th-Sc-Zr/10 
(Figure 5.20), majority of the phyllites plot within the passive margin confirming derivation 
of sediments from passive continental margin.  
In general, the geochemical characteristics of the phyllites indicate that the Neoproterozoic 
phyllites from the Akuapim range were predominantly derived from sediments deposited in a 
passive continental margin and/or intra-cratonic terranes.  
 
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Figure 5.17 Plot of Th/Sc versus Sc for Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (after McLennan and Taylor, 1991). 
 
 
Figure 5.18 Plot of La/Y versus Sc/Cr for Neoproterozoic phyllites from the Akuapim range, 
southeastern Ghana (after Bhatia and Crook 1986). 
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Figure 5.19 La-Th-Sc ternary diagram for the Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana (modified after Bhatia and Crook, 1986). A: oceanic island arc; B: 
continental island arc; C, D: active continental margin and passive margin. 
 
 
     
Figure 5.20 (a) Th-Co-Zr/10 and (b) Th-Sc-Zr/10 ternary diagrams for Neoproterozoic 
phyllites from the Akuapim range, southeastern Ghana (after Bhatia and Crook, 1986). PM: 
passive margin; ACM: active continental margin; CIA: Continental island arc; OIA: oceanic 
island arc.
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5.4 CRUSTAL EVOLUTION 
Numerous workers have investigated surface samples from various Precambrian shields in 
North America, Western Europe, Australia, India, South Africa and West Africa (Condie, 
1993; McLennan and Xiao, 1998; Asiedu et al., 2004). These studies have helped in the 
estimation of the chemical composition of the upper continental crust which is now well 
known. However, recent studies have shown that variations in the chemical composition 
specifically trace element abundance occur between the Archean and post-Archean Upper 
Continental Crust (Condie, 1993; Plank and Langmuir, 1996; Asiedu et al., 2004). Taylor and 
McLennan (1985) suggested that these variations were as a result of sedimentary processes 
and Plank and Langmuir (1996) suggested that the dilution of marine terrigeneous sediments 
with low trace elements bearing siliceous and carbonate sediments probably lead to the 
variation in chemical composition of the upper crust. McLennan and Xiao (1998) proposed 
that the cause of this variation may be due to combination of regional variations, difficulties 
in formulating averages and analytical difficulties.  
These hypothetical variations in trace element compositions of rocks between Archean and 
post-Archean Upper Crust can be observed by the following geochemical signatures (Condie, 
1993):  
1) A decrease in Eu anomalies; 
2) A decrease in GdN/YbN values from > 2 to 1.0 – 2.0; 
3) A decrease in Sm/Nd ratio from about 0.21 to 0.19; 
4) A decrease in Cr/Th values from about 20.0 to 5.7; 
5) A decrease in the Cr/Sc values from about 13 to 4.1; and 
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6) An increase in the Th/Sc values from about 0.5 to 1.0. 
Studies by Asiedu et al. (2004) on metagraywackes and metapelites from the Paleoproterozoic 
Birimian Supergroup in the Birim diamondiferous field, southern Ghana, one of the 
Precambrian shields, showed typical Archean signatures; low Th/Sc ratios (<0.5, with 
exception of one sample), high Sm/Nd ratios (>2.1, with exception of 3 samples), high Th/Sc 
ratios (>20, with exception of 3 samples), and high Cr/Sc ratios (>6, with exception of 2 
samples). These characteristic features suggest that the continental crust of the region in Ghana 
(and possibly for West Africa) during the early Proterozoic had chemical compositions similar 
to those of the Archean crust (Abouchami et al., 1990; Leube et al., 1990; Sylvester and Attoh, 
1992; Taylor et al., 1992).  
However, the Neoproterozoic phyllites from the Akuapim range show trace element variations 
which are typical of post-Archean sedimentary rocks. These variations include the relatively 
low average Eu anomalies (average Eu/Eu* = 0.61), decrease in GdN/YbN values (average = 
1.46), a decrease in Sm/Nd ratio (average = 0.19) a decrease in Cr/Sc (average = 4.56) and 
increase in Th/Sc values (average = 1.22), suggesting a significant compositional variation 
through time. The phyllites show relatively low GdN/YbN ratios (average = 1.46) which are 
significantly lower than 2 characteristic of sedimentary rocks of post-Archean age (McLennan 
and Taylor, 1991). A plot of Eu/Eu* against GdN/YbN = 2.0 (after McLennan and Taylor, 1991) 
is very useful in the evaluation of trace element variation of the Upper Continental Crust 
composition through time. On this plot (Figure 5.21), the phyllites compares favourably with 
Post-Archean sedimentary rocks and further away from the Birimian metasediments which 
suggests compositional variation in their trace elements through time.  
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Figure 5.21 Plot of Eu/Eu* versus GdN/YbN for Neoproterozoic phyllites from the Akuapim 
range, southeastern Ghana (after McLennan and Taylor, 1991). Birimian metasediments and 
Post-Archean Australian (average) Shale (PAAS) are plotted for comparison (values are from 
Asiedu et al., 2004; Taylor and McLennan, 1985, respectively).  
 
 
 
 
 
 
 
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5.5 LOCATION OF SOURCE AREA 
Grant (1969) and Affaton et al. (1980) suggested that the Buem Structural Unit is a laterally 
equivalent of the Middle Voltaian, which is, the Afram and Oti Group in Ghana and the 
Pendjari Group in Togo, Benin and Burkina Faso. In addition, Affaton et al. (1980) suggested 
that the Togo Structural Unit is a lateral equivalent of the Kwahu/Bombouka Group of the 
Voltaian Basin. However, studies by Kalsbeek et al. (2008), which involved Pb-Pb zircon 
dating of rocks from the Voltaian, Buem Structural Unit and Togo Structural Unit revealed 
that the Lower Voltaian (Kwahu/Bombouaka Group), the Buem Structural Unit and the Togo 
Structural Unit have similar ages and were probably derived from same  source. They 
interpreted that the Togo Structural Unit and some parts of the Buem Structural Unit correlate 
with the Kwahu/Bombouaka Group (Figure 5.22).  
The rocks of the Kwahu/Bombouaka Group are believed to have been deposited on a passive 
margin associated with the opening of a Pan-African ocean (Kaslbeek et al., 2008). Also, 
studies by Osae et al. (2006), showed that the rocks of Buem Structural Unit were deposited 
on a passive margin that received large amounts of mature detritus from the hinterland areas. 
In this study, the provenance characteristics of the Togo Phyllites indicate that the rocks were 
probably deposited on a passive margin. These conclusions support the interpretation that the 
Kwahu/Bombouaka Group, Buem Structural Unit and Togo Structural Unit are lateral 
equivalents and were probably derived from the same source. 
The rocks of the Kwahu/Bomabouaka Group, Togo Structural Unit and Buem Structural Unit 
reveal zircons ages of 1000-1300 Ma (Kalsbeek et al. 2008). From the geology of Ghana, no 
rocks of this age range had been observed in Ghana. According to Kalsbeek et al. (2008), this 
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age range is typical of rocks derived from sources outside the West African Craton and 
probably from sources in the Amazonian Craton. This assertion was supported by the 
following evidences: 
1) The Amazonian craton was situated close to the West African Craton during the 
supercontinent Rodinia around 1000-1200 Ma; 
2) The prevalence of rocks with ages between 1000-2000Ma in the Amazonian Craton. 
(e.g. Santos et al., 2000; Tassinari et al., 2000);  
3) The predominance of northerly paleocurrent directions in the rocks of the 
Kwahu/Bombouaka Group (Junner, 1940).  
Kalsbeek et al. (2008) concluded that sediments from the Kwahu/Bombouaka Group rocks 
were probably derived from sources in the Amazonian Craton. Considering the similar tectonic 
setting and depositional ages as well as the lateral correlation between the Kwahu/Bombouaka 
Group and the Togo Structural Unit, the Togo Phyllites were probably derived from sources 
in the Amazonian Craton. However, detailed geochemistry such as zircon dating of the Togo 
Phyllites must be carried out in order to ascertain this assertion. 
 
Figure 5. 22 Correlation between the lithological logs of the Togo Structural Unit (after Blay, 
1991), the Voltaian (after Affaton, 1990) and the Buem Structural Unit (after Osae et al., 2006). 
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CHAPTER SIX 
CONCLUSIONS AND RECOMMENDATIONS 
6.1 CONCLUSIONS 
The Neoproterozoic phyllites from the Akuapim range have been for their mineralogy and 
geochemistry. The results are broadly in agreement and the main conclusions are: 
1) From geochemical data, the phyllites can be classified mostly as quartz-rich with few 
quartz-intermediate. 
2) The phyllites show geochemical characteristics typical of mature sediments probably 
derived from an intensely weathered source. 
3) The mineralogical and geochemical characteristics of the phyllites indicate that the 
sediments are mainly derived from an old Recycled Upper Continental Crust. 
Provenance modeling of the Togo Phyllites shows that the phyllites are composed of a 
mixture of ~80% Upper Continental Crust and 20% granite.  
4) The phyllites exhibit mineralogical and geochemical characteristics indicative of 
sediments derived from stable continental areas and deposited on a passive continental 
margin.  
5) Trace element data of the phyllites show characteristics that closely resemble those of 
post-Archean sediments suggesting that, the chemical composition of the continental 
crust in the study area during the Proterozoic are different from the Archean crust. 
6) The phyllites show provenance characteristics similar to that of the Lower Voltaian 
(Kwahu/Bombouaka Group) and Buem Structural Unit which suggest that the 
sediments were possibly derived from the same sources in the Amazonian craton. 
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6.2 RECOMMENDATIONS 
The Neoproterozoic phyllites from the Akuapim range show coherent mineralogical and 
geochemical characteristics which indicate derivation of sediments from one source.  It is 
therefore recommended that single-grain analyses such as Sensitive High Resolution Ion 
Micro-Probe (SHRIMP) determinations of 207Pb/206Pb to determine ages of detrital zircons 
should be carried out to compare with known ages of possible source rocks to test this 
hypothesis. 
Also, Sm-Nd isotopic composition of the phyllites should be carried out to provide more 
information on the composition of the source terrane and age at which the source igneous rocks 
separated from the mantle.  
In addition, further petrographical and geochemical studies are recommended in other areas of 
the Togo Structural Unit to give a better and broad understanding of the provenance of this 
unit.  
 
 
 
 
 
 
 
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REFERENCES 
Abouchami, W., Boher, M., Michard, A. and Albarede, F. (1990). A major 2.1 Ga old event
 of mafic magmatism in West Africa: An early stage of crustal accretion. J. Geophys.
 Res. 95, pp.17605-17629. 
Adjei, A. O. (1968). The structural geology and petrology of the Awudome-Abutia area. MSc.
 Thesis, University of Ghana, Legon, 136 pp.  
Affaton, P., Sougy, J. and Trompette, R. (1980). The tectono-stratigraphic relationships
 between the Upper Precambrian and Lower Paleozoic Volta Basin and the Pan -
 African Dahomeyide orogenic belt (West Africa). Am. J. Sci. 280, pp. 224-248. 
Affaton P. (1990). Le bassin des Volta (Afrique de l’Ouest): une marge passive, d’âge
 protérozoïque supérieur, tectonisée au Panafricain (660-150 Ma). Editions ORSTOM,
 Collection Etudes et Thèses, Paris, 500 p. 
Affaton, P., Rahaman, M. A., Trompette, R. and Sougy, J. (1991). The Dahomeyide Orogen:
 tectonothermal evolution and relationships with the Volta basin. In: Dallmeyer, R. D.,
 Lecorchˊ e, J. P. (Eds). The West African Orogens and Circum-Atlantic Correlatives.
 Springer, New York, pp. 95-111. 
Affaton, P., Aguirre, L. and Meˊnot, R. P. (1996). Thermal and geodynamic setting of the
 Buem volcanic rocks near Tiéle, Northwest Benin, West Africa. Precambrian
 Research, 82, pp. 191-209. 
Agbossoumonde, Y., Guillot, S. and Mˊenot, R. P. (2004). Pan-African subduction-collision
 event evidenced by high-P coronas in meta-norites from the Agou Massif (southern
 Togo). Precambrian Res., 135, pp. 1-21.  
Ahmed, S. M., Blay, P. K., Castor, S. B. and Coakley, G. J. (1977). Geology of field sheet 33,
 59, 61 and 62. Winneba N. W. Accra S. W. N. W., and N. E., respectively. Ghana
 Geological Survey Bulletin, 32. 
Akarish, A. I. M. and El-Gohary, A. M. (2008). Petrography and Geochemistry of Lower
 Paleozoic sandstones, East Sinai, Egypt: implications for provenance and tectonic
 setting. Journal of African Earth Sciences, 52 (1), pp. 43-54. 
Amoah, E. (2009). Geochemistry and Provenance of Neoproterozoic metasedimentary rocks
 from the Akwapim segment of the Togo Structural Unit, southeatern Ghana. M.Phil.
 thesis, University of Ghana, pp. 80. 
Armstrong-Altrin, J. S., Lee, Y. I., Verma, P. S. and Ramasamy, S. (2004). Geochemistry of
 sandstones from the upper Miocene Kudan Kulan formation, southern India:
 Implication for provenance, weathering and tectonic setting. Journal of Sedimentary
 Research, 74(2), pp. 285-297. 
98 
 
University of Ghana http://ugspace.ug.edu.gh
Asiedu, D. K., Suzuki, S., Nogami, K and Shibata, T. (2000). Geochemistry of Lower
 Cretaceous sediments, Inner Zone of Southwest Japan: Constraints on provenance
 and tectonic environment. Geochemical Journal, 34, pp. 155-173.  
Asiedu, D. K., Damapare, S. B., Sakyi, P. A., Banoeng – Yakubo, B., Osae, S., Nyarko, B. J.
 B., and Manu, J. (2004). Geochemistry of Paleoproterozoic metasedimentary rocks
 from the Birim diamondiferous field, southern Ghana: Implications for provenance
 and crustal evolution at the Archean-Proterozoic boundary. Geochemical Journal, 38,
 pp. 215-228. 
Asiedu, D. K., Dampare, S. B., Shibata, T., Banoeng-Yakubo, B. and Osae, S. (2006). The
 chemical composition and significance of chromian spinels in the Neoproterozoic
 Anum serpentinites obtained from Anum and Dake-Peki in south eastern Ghana.
 Journal of Ghana Science Association. 10: 1: 36-43. 
Asihene, L. A. B. and Barning, K. (1975). A contribution to the stratigraphy of the Birrmian
 System of Ghana, West Africa. Ghana Geological Survey Report, 75, 5, pp. 30. 
Attoh, K. (1990). Dahomeyides of Southeastern Ghana: Evidence for oceanic closure and
 crustal imbrication in a Pan-African orogen. Publication occasionnelle du C.I.F.E.G.,
 BRGM, Orleans Tr. No. 21. 
Attoh, K. (1998). High-pressure granulite facies metamorphism in the Pan-African
 Dahomeyide orogen, West Africa. Journal of Geology, 106, pp. 236-246. 
Attoh, K., Dallmeyer, R. D. and Affaton, P. (1997). Chronology of nappe assembly in the Pan
 African Dahomeyide orogen, West Africa: evidence from 40Ar/39Ar mineral ages.
 Precambrian Research 82, 135-171. 
Attoh, K. and Nude, P. M. (2008). Tectonic significance of carbonatite and ultrahigh-pressure
 rocks in the Pan-African Dahomeyide suture zone, southeastern Ghana. Geological
 Survey, London, Special Publications, 2008, v. 297, pp. 217-231. 
Barbera, G., Mazzoleni, P., Critelli, S., Pappalardo, A., Giudice1, A. L. and Cirrincione, R.
 (2006). Provenance of shales and sedimentary history of the Monte Soro Unit, Sicily.
 Per. Mineral. 75, 2-3, pp. 313-330. 
Barshad, I. (1966). The effect of a variation in precipitation on the nature of clay mineral
 formation in soils from acid and basic igneous rocks. Proc. Intl. Clay Conf., pp. 167 -
 173. 
Basu, A. (1976). Petrology of Holocene fluvial sand derived from plutonic source rocks:
 Implication to paleoclimatic interpretation: Journal of Sedimentary Petrology, 46, pp.
 694-709. 
Bates, D. A. (1955). Geological map of Ghana. Ghana Geological Survey Department.
 Reprinted by the Survey in 1966. 
99 
 
University of Ghana http://ugspace.ug.edu.gh
Bavinton, O. A. and Taylor, S. R. (1980). Rare earth element abundances in Archean
 metasediments from Kambalda Western Australia. Geochimiva et Cosmochimica
 Acta, 44, pp. 639-648. 
Bennett, P. and Siegel, D. I. (1987). Increased solubility of quartz in water due to complexing
 of organic compounds: Nature, 326, pp. 684-687. 
Bhatia, M. R. (1983). Plate tectonics and geochemical composition of sandstones. Journal of
 Geology, 91, pp.  611-627. 
Bhatia, M. R. (1984). Composition and classification of Paleozoic flysch mudrocks of eastern
 Australia: Implications in provenance and tectonic setting interpretation. Sedimentary
 Geology, 41(2), pp. 249-268. 
Bhatia, M. R. (1985). Rare earth element geochemistry of Australian Paleozoic graywackes
 and mudrocks: provenance and tectonic controls. Sedimentary Geology, 45, pp. 97 -
 113. 
Bhatia, M. R. and Crook, K. A. W. (1986). Trace elements characteristics of greywackes and
 tectonic setting discrimination of sedimentary basins. Contributions to Mineralogy and
 Petrology, 92, pp. 181-193. 
Black, R., Caby, R., Moussine-Pouchkine, A., Bayer, R., Bertrand, J. M., Boullier, A. M.,
 Fabre, J. and Lesquer, A. (1979). Evidence for late Precambrian plate tectonics in West
 Africa. Nature, 278, 223-227. 
Blatt, H., Middleton, G. V. and Murray, R. (1980). Origin of sedimentary rocks. Englewood
 cliffs, New Jersey, prentice-Hall. Pp.782. 
Blay, P. K. (1991). Applying subduction tectonics to the evolution of the Pan-African
 Dahomeyide deformed belt of Ghana, West Africa. Proceedings of the first local
 conference on Mineral Exploration and Development and their impact on the Economy
 of Ghana, Accra, 7th December, 1990. Minerals Commission Publication, pp. 52-57. 
Bock, B., McLennan, S. M. and Hanson, G.N. (1998). Geochemistry and provenance of the
 Middle Ordovician Austin Glen Member (Normanskill Formation) and the Taconian
 Orogeny in New England. Sedimentology, 45, pp. 635-655. 
Boles, J. R. (1984). Secondary porosity reactions in the Stevens Sandstone, San Joanquin
 Valley, Carlifornia. In: McDonald, D. A. and Surelam, R. C. eds., Clastic diagenesis:
 American Association of Petroleum Geologist Memoir, 37, pp. 217-224. 
Boullier, A. M., Liegeois, J. P., Black, R., Fabre, J., Sauvage, M. and Bertrand, J. M. (1986).
 Late Pan-African tectonics marking the transition from subduction-related talc 
 alkaline magmatism to within-plate alkaline granitoids (Adrar des Iforas, Mali). In:
 B. Johnson and A.W. Bally (Editors), Intraplate Deformation: Characteristics,
 Processes and Causes. Tectonophysics, 132, 233-246. 
100 
 
University of Ghana http://ugspace.ug.edu.gh
Boynton, W. V. (1984), Cosmochemistry of the rare-earth element; meterorite studies. In:
 Rare earth element geochemistry. Henderson, P. (Editors), Elsevier SCi, Publ. Co.,
 Amsterdam, pp. 63-114. 
Bracciali, L., Marroni, M., Pandolfi, L. and Rocchi, S. (2007). Geochemistry and petrography
 of Western Tethys Cretaceous sedimentary covers (Corsica and Northern Apennines):
 from source area to contigration of margins. In: Arribas, J., Critelli, S., Johnsson, M. J.
 (Eds.), Sedimentary provenance and petrogenesis: Perspectives from petrography and
 Geochemistry. Geo. Soc. Am. Spe. Paper, 420, pp.73-93. 
Bradely, W. C. (1970). Effect of weathering on abrasion of granitic gravel, Colorado River
 (Texas): Geological Society of America Bulletin, 81, pp. 61-80. 
Brookins, D. G. (1989). Aqueous geochemistry of rare-earth element. In Lipin, B. R. and
 McKay, G. A., eds., Geochemistry and Mineralogy of Rare-earth element.
 Washington, Mineralogical Society of America, pp. 201-226. 
Burke, K. C. and Dewey, J. F. (1972). Orogeny in Africa. In: Dessauvagie, T. F. J., Whiteman,
 A. J. (Eds), African Geology. Departtment of Geology, University of Ibadan, Nigeria,
 pp. 583-608. 
Caby, R., Bertrand, J. M. and Black, R. (1981). Pan-African ocean closure and continental
 collision in the Hoggar-Iforas segment, Central Sahara. In: A. Kroner (Editor),
 Precambrian Plate Tectonics. Elsevier, Amsterdam, pp. 407-434. 
Caby, R. (1987). The Pan-African belt of West Africa from the Sahara Desert to the Gulf of
 Benin. In: Schaer, J. P., Rodgers, J. (Eds.), Anatomy of Mountain Ranges. Princeton
 University, pp. 129-170. 
Camiré, G. E., Laflèche, M. R. and Ludden, J. N. (1993). Archean metasedimentary rocks from
 the northwestern Pontiac subprovince of the Canadian Shield: Chemical
 characterization, weathering and modelling of the source areas. Precam. Res., 62, pp.
 285-305. 
Castaing, C., Triboulet, C., Feybesse, J. L. and Chevremont, P. (1993). Tectonometamorphic
 evolution of Ghana, Togo, and Benin in the light of the PanAfrican/Brasiliano orogeny.
 Tectonophysics, 218, pp. 323-342. 
Chamley, H. (1990). Sedimentology. Springer-Verlag, Berlin. 
Chen, X., Shu. L., Santosh M. and Xu, Z. (2014). The provenance and tectonic affinity of the
 Paleozoic meta-sedimentary rocks in the Chinese Tianshan belt: New insights from
 detrital zircon U-Pb geochronology and Hf-isotope analysis. A Journal of Asian earth
 Sciences, 94, pp. 12-27. 
Clifford, T. N. (1972). The evolution of the crust of Africa. Service Geˊol. Maroc., Notes
 Meˊm. No. 236, pp. 29-39. 
101 
 
University of Ghana http://ugspace.ug.edu.gh
Condie, K. C. (1993). Chemical composition and evolution of the upper continental crust:
 Contrasting results from surface samples and shales. Chemical geology, 104, pp. 1 -
 37. 
Condie, K. C., Boryta, M. D., Liu, J. and Quian, X. (1992). The origin of khondalites:
 geochemical evidence from the Archean to Early Proterozoic granulitic belt in the
 North China Craton. Precambrian Research, 59 (3-4), pp. 207-223. 
Condie, C. K., Noll, P. D., Jr. and Conway, C. M. (1992). Geochemical and detrital mode
 evidence for two sources of Early Proterozoic sedimentary rocks from the Tonto Basin
 Supergroup, central Arizona. Sedimentary geology, 77, pp. 51-76. 
Cordani, U. G., D’agrella-Filho, M. S., Brito-Neves, B. B. and Trindale, I. F. (2003). Tearing
 up Rodinia: the Neoproterozoic paleogeography of South American cratonic
 fragments. Terra Nova, 15, pp. 350-359. 
Cox, R. (1993). Sediment recycling, crustal development and compositional evolution of
 elastic sediments, southwestern United States. Ph.D. thesis, Stanford University.
 University Microfilms. 
Cox R. and Lowe D. R. (1995a). A conceptual review of regional-scale controls on the
 composition of clastic sediment and the co-evolution of continental blocks and their
 sediment cover. Journal of Sedimentary Research, A65 No 1, pp. 1-12. 
Cox, R. and Lowe, D. R. (1995b). Compositional evolution of coarse elastic sediments in the
 southwestern United States. I. Sediment Res. A65 (in press). 
Cox R., Lowe D. R. and Cullers R. L. (1995). The influence of sediment recycling and
 basement composition on evolution of mudrock chemistry in the southwestern United
 States. Geochim. Cosmochim. Acta, 59, 14, pp. 2919-2940. 
Crook, J. P. (1963). The geology of the field sheets 142, 144 and 147. Ho, S. E. and N. E and
 Honuta N. W. Unpublished report of Ghana Geological Survey. 
Crook, J. P. (1970). Some preliminary notes on the classification of rocks of Eastern Ghana in
 Geological Survey Bulletin no. 38. Symposium Fiftieth Anniversary-Ghana
 Geological Survey 1913-1963, pp. 27-32. 
Crook, K. A. (1974). Lithogenesis and geotectonics: The significance of compositional
 variation in flysch arenites (graywackes). In Dott, R. H., Jnr. And Shaver, R. H. eds.
 Modern and Ancient Geosynclinal Sedimentation. Soc. Econ. Paleontologists
 Mineralogists Special Publication, 19, pp. 304-310. 
Cullers R. L. (1994). The controls on the major and trace element variation of shales, siltstones
 and sandstones of Pennsylvanian-Permian age from uplifted continental blocks in
 Colorado to platform sediment in Kansas, U.S.A. Geochimica Cosmochimica Acta, 58,
 pp. 4955-4972. 
102 
 
University of Ghana http://ugspace.ug.edu.gh
Cullers, R. L. (1994a). The chemical signature of source rocks in size fractions of Holocene
 stream sediment derived from metamorphic rocks in the Wet Mountains region, USA.
 Chemical Geology, 113, pp. 327-343. 
Cullers, R. L. (1994b). The controls on the major and trace element variation of shales,
 siltstones, and sandstones of Pennsylvanian-Permian age from uplifted continental
 blocks in Colorado to platform sedimentin Kansas, USA. Geochim. Cosmochim. Acta
 58, pp. 4955-4972. 
Cullers R. L. (2000). The geochemistry of shales, siltstones and sandstones of Pennsylvanian
 Permian age, Colorado, USA: implications for provenance and metamorphic studies.
 Lithos., 51, pp. 181-203. 
Cullers, R. L. (2002). Implications of elemental concentrations for provenance, redox
 conditions, and metamorphic studies of shales and limestones near Pueblo, CO, USA:
 Chemical Geology, 191(4), pp. 305-327. 
Cullers, R. L., Chaudhuri, S., Arnold, B., Lee M. and Wolf, W. J. (1975). REE distributions in
 clay minerals and in the clay-sized fraction of the lower Permian Havensville and
 Eskridge shales of Kansas and Oklahoma. Geochim. Cosmochim. Acta, 39, pp. 1691-
 1703. 
Cullers, R.L., Chaudhuri, S., Kilbane, N. and Koch, R. (1979). Rare earths in size fractions
 and sedimentary rocks of Pennsylvanian-Permian age from the mid-continent of the
 USA. Geochimica et Cosmochimica Acta, 43, pp. 1285-1302. 
Cullers, R. L. and Graf, J. (1984). Rare earth element in igneous rocks of the continental crust:
 intermediate and silicic rocks, ore petrogenesis, in Henderson, P. (ed.), Rare earth
 geochemistry. Elsevier, pp. 275-316. 
Cullers, R. L., Basu, A. and Suttner, L. (1988). Geochemical signature of provenance in sand
 size material in soils and stream sediments near the Tobacco Root batholith, Montana,
 USA. Chemical Geology, 70(4), pp. 335-348. 
Cullers, R. L. and Podkovyrov, V. M. (2000). Geochemistry of the Mesoproterozoic Lakhanda
 shales in southeastern Yakutia, Russia: Implications for mineralogical and
 provenance, and recyling. Precambrian Research, 104, pp. 77-93. 
Cullers, R. L. and Podkovyrov, V. N. (2002). The source and origin of terrigenous sedimentary
 rocks in the Mesoproterozoic Ui group, south-eastern Russia. Precambrian Research,
 117, pp. 157-183. 
Dabard, M. P. (1990). Lower Brioverian formations (Upper Proterozoic) of the Armorican
 Massif (France): geodynamic evolution of the source areas revealed by sandstone
 petrography and geochemistry. Sedimentary geology, 69, pp. 45-58. 
Dapaah-Siakwan, S. and Gyau-Boakye, P. (2000). Hydrogeologic framework and borehole
 yields in Ghana. Hydrogeology Journal, 8, pp. 405-416. 
103 
 
University of Ghana http://ugspace.ug.edu.gh
Dampare, S. B., Asiedu, D. K., Osae, S., Manu, J. and Banoeng-Yakubu, B. (2004).
 Geochemistry of Lower Proterozoic greywackes from the Birim Diamondiferous Field,
 Ghana. African Journal of Science and Technology (AIST), Science and Engineering
 series, 5: 2. pp. 9-18. 
Davies, B. E. (1980). Applied Soil Trace Elements. Wiley. 
Davis, D. W., Hirdes, W., Schaltegger, U. and Nunoo, E. A. (1994). U-Pb age constraint on
 the deposition of Birimian and gold bearing Tarkwaian sediments in Ghana, West
 Africa. Precambrian Research, 67, pp. 89-107. 
De, S., Mazumder, R., Ohta, T., Hegner, E., Yamada, K., Bhattacharyya, T., Chiarenzelli, T.,
 Altermann, M. and Arima, M. (2015). Geochemical and Sm-Nd isotopic
 characteristics of the Late Archaean-Palaeoproterozoic Dhanjori and Chaibasa
 metasedimentary rocks, Singhbhum craton, E. India: Implications for provenance, and
 contemporary basin tectonics. Precambrian Research, 256, pp. 62-78. 
Dickinson, W. R. and Suczek, C. A. (1979). Plate tectonics and sandstone compositions:
 America Association of Petroleum Geologists Bulletin, 63, pp. 216-2182. 
Dickson, K. B. and Benneh, G. (1988). A New Geography of Ghana. Longman Group. 
Dickinson, W. R., Beard, L. S., Brakenridge, G. R., Erjavec, J. L., Ferguson, R. C., Inman, K.
 F., Knepp, R. A., Lindberg, F. A. and Ryberg, P. T. (1983). Provenance of North
 American Phanerozoic sandstones in relation to tectonic setting. Bull. Am. Geol.
 Soc., 94, 222 - 235. 
Dickinson, W. R. (1985). Interpreting provenance relations from detrital modes of sandstones.
 In: Zuffa, G. (Ed.), Provenance of Arenites. Reidel, Dordrecht, pp. 333-361. 
Drost, K., Linnemann, U., Wemmer, K., Petr Budil, P., Kraft, P., Fatka, O. and Marek, J.
 (2003). Provenance and early diagenetic processes of the Ordovician Šárka Formation
 at Praha Červený vrch Hill (Barrandian, Czech Republic). Bulletin of Geosciences,
 Vol. 78, No. 2, pp. 147-156. 
Dutta, P. K. and Wheat, R. W. (1993). Climatic and tectonic control on sandstone composition
 in the Permo-Triassic Sydney foreland basin, Eastern Australia. In: Johnsson, M. J.
 and Basu, A. eds., Processes Controlling the Composition of Clastic sediments,
 Geological Society of America Special Paper, 284, pp. 187-203. 
Enkeboll, R. H. (1982). Petrology and provenance of sands and gravels from the Middle
 America Trench slope, southwestern Mexico and Guatemala: Initial report of the Deep
 Sea Drilling Project. 66, pp. 521-530. 
Ermolenko, N. F. (1972). Trace Elements and Colloids in Soils. Israel Program for Scientific
 Translations. 
104 
 
University of Ghana http://ugspace.ug.edu.gh
Faupl, P., Pavlopoulos, A., Klotzli, U. and Petrakakis, K. (2002). Detrital blue amphiboles
 from the western Othrys Mountain and their relationship to the blueschist terrains of
 the Hellenides (Greece). International Journal of Earth Sciences 91, pp. 433-444. 
Fedo, C. M., Nesbitt, H. W. and Young, G. M. (1995). Unravelling the effects of potassium
 metasomatism in sedimentary rocks and paleosoils, with implications for
 paleoweathering rogstad, E. J. (1996). Geochemistry of shale from the Archean (~3.0
 Ga) Buhwa Greenstone belt, Zimbabwe: Implications for provenance and source area
 weathering. Geochimica et Cosmochimica Acta, 60, 10, pp. 1751-1763. 
Fedo, C. M., Eriksson, K. A. and Blenkinsop, T. G. (1996). Geologic history of the Archean
 Buhwa Greenstone Belt and surrounding granite-gneiss terrane, Zimbabwe with
 implications for the evolution of the Limpopo Belt. Canadian, J. Earth Sci., 32, pp.
 1977-1990. 
Fedo, C. M., Young, G. M. and Nesbitt, H. W. (1997), Paleoclimatic control on the
 composition of the Paleoproterozoic Serpent Formation, Huronian Supergroup,
 Canada: a greenhouse icehouse transition. Precambrian Research, 86, pp. 201-223. 
Feng, R. and Kerrich, R. (1990). Geochemistry of fine-grained clastic sediments in the
 Archean Abitibi greenstone belt, Canada: Implications for provenance and tectonic
 setting. Geochimica Cosmochimica, Acta, 54, pp. 1061-1081. 
Floyd, P A. and Leveridge, B. E. (1987). Tectonic environment of the Devonian Gramscatho
 basin, south Cornwall: framework mode and geochemical evidence from turbidite
 sandstones. Journal of the Geological Society of London, 144, pp. 531-542.  
Floyd, P. A., Winchester, J. A. and Park, R. G. (1989). Geochemistry and tectonic setting of
 Lewisian clastic metasediments from the Early Proterozoic Loch Maree Group of
 Gairloch, N. W. Scotland. Precambrian Research, 45(1-3), pp. 203-214.  
Folk, R. L. (1974). Petrology and provenance of Sedimentary Rocks. Hemphill Publicator Co.,
 Austin, Texas, pp. 170-182. 
Franks, S. G. and Foster, R. W. (1984). Relationship among secondary porosity, pore fluid
 chemistry and carbon dioxide, Texas Gulf Coast. In: McDonald, D. A. and Surelam,
 R. C. eds., Clastic diagenesis: American Association of Petroleum Geologist Memoir,
 37, pp. 63-79. 
Franzinelli, E. and Potter, P.F. (1983). Petrology, chemistry and texture of modern river sands,
 Amazon River system. Journal of Geology, 91, pp. 23-39. 
Gao, S. and Wedepohl, K. H. (1995). The negative Eu anomaly in Archean sedimentary rocks:
 implications for decomposition, age and importance of their granitic sources. Earth
 Planet. Sci. Lett., 133, pp. 81-94. 
105 
 
University of Ghana http://ugspace.ug.edu.gh
Garvanti, E. (1986). Source rock versus sedimentary control on mineralogy of deltaic volcanic
 Arenites (Upper Triassic, northern Italy). Journal of Sedimentary Petrology, 56, pp.
 267-275. 
Getaneh, W. (2002). Geochemistry provenance and depositional tectonic setting of the Adigrat
 Sandstone northern Ethiopia. Journal of African Earth Sciences, 35, pp. 185-198. 
Ghana National Geological Map Project. (2009). Geological Survey Department of Ghana and
 Bundesansalt fur Geowiessenschaften und Rohstoffe (BGR), Germany. 
Gibbs, A. K., Montgomery, C. W., O'day, P. A. and Ersleve, A. (1986). The Archean
 Proterozoic transition: evidence from the geochemistry of metasedimentary rocks of
 Guyana and Montana. Geochimica et Cosmochimica Acta, 50, pp. 2125-2141. 
Girty, G. H., Mossman, B. J. and Pincus, S. D. (1988). Petrology of Holocene sand, pennisua
 ranges, Carlifornia and Baja Norte, Mexico: Implications for provenance
 discrimination models, Journal of Sedimentary Petrology, 58, pp. 881-887. 
Goldberg, E. (1954). Marine geochemistry 1-chemical scavengers of the sea. Journal of
 Geology, 62, pp. 249 – 265. 
Goldich, S. S. (1938). A study in rock weathering. Journal of Geology, 46, pp. 17-58. 
Grant, W. H. (1963). Weathering of Stone Mountain Granite, in Ingersoll, E. C., ed., Clays
 and Clay Minerals, 11, pp. 65-73. 
Grant, N. K. (1967). Complete late pre-Cambrian to early Paleozoic orogenic cycle in Ghana,
 Togo and Dahomey. Nature, 215, pp. 609-610. 
Grant, N. K. (1969). The Precambrian to early Paleozoic orogeny in Ghana, Togo, Dahomey
 and Nigeria. Geological Society of America Bulletin, 80, pp. 45-55. 
Griffis, R. J., Barning, K., Agezo, F. L. and Akosah, F. K. (2002). Gold Deposits of Ghana. 
 Accra, Ghana: Minerals Commission. 
Hansley, P. L. (1987). Petrology and experimental evidence for the etching of garnets by
 organic acid in the Upper Jurassic Morrison Formation, northwestern New Mexico:
 Journal of Sedimentary Petrology, 57, pp. 666-681. 
Hanson, G. N. (1980). Rare-earth element in petrogenetic studies in igneous systems. Ann.
 Rev. Earth Planet. Sci., 8, pp. 371-406. 
Harker, A. (1909). The natural history of igneous rocks. Metheun, London. 
Harnois, L. (1988). The CIW index: a new chemical index of weathering. Sedim. Geol., 55,
 pp. 319-322. 
Harris, R. C. and Adams, J. A. S. (1966). Geochemical and mineralogical studies on the
 abundances of the rare earths. In Ahrens, L. H., eds., Origin and Distribution of the
 Elements. New York, Pergamon, pp. 889-912.  
106 
 
University of Ghana http://ugspace.ug.edu.gh
Hasting, D. A. (1977). Gravity mapping and interpretation in Ghana. Amer. Geophy. Un.
 Trans. USA. 58, 6. Cape Coast and Saltpond District. Geological Survey of Ghana
 Bulletin, 29. 
Hayashi, K., Fujisawa, H., Holland, H. and Ohmoto, H. (1997). Geochemistry of ∼1.9 Ga
 sedimentary rocks from northeastern Labrador, Canada. Geochimica et Cosmochimica
 Acta, 61(19), pp. 4115-4137. 
Hayes, M. O. (1967). Hurricanes as geological agents, south Texas Coast. America Society
 Petrology, 51, pp. 937-942. 
Heller, P. L. and Frost, C. D. (1988). Isotopic Provenance of Clastic Deposits: Application of
 Geochemistry to Sedimentary Provenance Studies. New Perspectives in Basin
 Analysis. Frontiers in Sedimentary Geology, pp. 27-42. 
Helmhold, K. P. and van de Kamp, P. C. (1984). Diagenetic mineralogy and controls on
 albitization and laumonitic formation in Paleogene arkoses; Santa Ynex Mountains,
 Carlifornia. In:McDonald, D. A. and Surdam, R. C. Clastic genesis. American
 Association of Petroleum Geologists Memoir, 37, pp. 239-276. 
Herron, M. M. (1988). Geochemical classification of terrigenous sands and shales from core
 or log data. Journal of Sedimentary Petrology, 58, 5, pp. 820-829. 
Hoffman, P. (1991). Did the breakout of Laurentia turn Gondwana inside out? Science, 252,
 pp. 1409-1412. 
Hoffman, P. (1999). The break-up of Rodinia, birth of Gondwana, true polar wander and the
 snowball Earth. Journal of African Earth Sciences, 28, 17-33. 
Holm, F. R. (1973). On the metamorphic facies of Dahomeyan gneisses in the Western Accra
 plains, Ghana. Mineralogical Society, 39, pp. 224-232. 
Holm, F. R. (1974). Petrology of alkalic gneiss in the Dahomeyan of Ghana. Geological
 Society of America Bulletin 85, pp. 1441-1448. 
Horowitz, A. J. (1991). A Primer on Sediment-Trace Element Chemistry Lewis Publishers. 
Horowitz, A. J. and Elrick, K. (1987). The relationship of stream sediment surface area,
 grainsize and composition to trace element chemistry. Applied Geochemistry, 2, pp.
 437-451. 
Hubert, J. F. (1962). A zircon-tourmaline-rutile maturity index and the interdependence of
 the composition of heavy minerals assemblage with the gross composition and texture
 of sandstones. Journal of Sedimentary Petrology, 32, pp. 440-450. 
Jahn, B. M. and Condie, K. C. (1995). Evolution of the Kaapvaal Craton as viewed from
 geochemical and Sm-Nd isotopic analyses of intracratonic pelites. Geochimica et
 Cosmochimica Acta, 59, pp. 2239-2258. 
107 
 
University of Ghana http://ugspace.ug.edu.gh
Johnsson, M. J. (1993). The system controlling the composition of clastic sediments. In:
 Johnsson, M. J, Basu, A., (Eds.), Processes Controlling the Composition of Clastic
 Sediments. Geological Society of America, Special Paper, 284, pp. 1-19. 
Johnsson, M. J., Stallard, R. F. and Lundberg, N. (1991). Controls on the composition of fluvial
 sands from a tropical weathering environments: sands from the Orinoco River drainage
 basin, Venezuela and Colombia. Geological Society of American Bulletin, 103, pp.
 1622-1647.  
Johnsson, M. J., Stallard, R. F. and Meade, R. H., (1988). First-cycle quartz arenites in the
 Orinoco River basin, Venezuela and Colombia. Journal of Geology, 96, pp. 263-277. 
Jones, W. B. (1990). The Buem volcanic and associated sedimentary rocks, Ghana: A field
 and geochemical investigation. J. Afr. Earth Sci., 11, pp. 373-383.  
Junner, N. R. (1940). The Geology of the Gold Coast and western Togoland. Gold Coast
 Geological Survey Bulletin, 11, pp. 1-40. 
Junner, N. R. and Service, H. (1936). Gold Coast Geol. Survey Annual Report, 1935-1936. 13,
 pp. 32-34. 
Junner, N. R. and Hirst, T. (1946). The geology and hydrology of the Voltaian basin. Gold
 Coast Geological Survey Memoir, 8, pp. 51. 
Kalsbeek, F., Frei, D. and Affaton, P. (2008). Constraints on provenance, stratigraphic
 correlation and structural context of the Volta basin, Ghana, from detrital zircon
 geochronology: An Amazonian connection? Sedimentary Geology, 212, pp. 86-95. 
Kasanzu, C., Makobo, A. H. M. and Manya, S. (2008). Geochemistry of fine-grained clastic
 sedimentary rocks of the Neoproterozoic IKorongo Group, NE Tanzania: implication
 for provenance and source rock weathering. Precambrian Research, 164, pp. 201 -
 213. 
Keizer, P. and Bruggenwert, M. G. M. (1991). Adsorption of heavy metals by clay-aluminum
 hydroxide complexes. In Interaction at the Soil Colloid-Soil Solution Interface (ed.
 G. H. Bolt et al.), pp. 177-204. Kluwer. 
Kelley, J. C. and Whetten, J. T. (1969). Qualitative Standard analyses of Columbis River
 sediments samples. Journal of Sedimentary Petrology, 39, pp. 1167-1173. 
Kennedy, W. Q. (1964). The structural differentiation of Africa in the Pan-African (+/- 500
 m. y) tectonic episode. Annual Report of the Research Institute of African Geology,
 University of Leeds. 8, pp. 48-49. 
Kesse, G. (1985). The mineral and rock resources of Ghana. United States: A. A. Balkema
 Publishers, Accord, MA. 
108 
 
University of Ghana http://ugspace.ug.edu.gh
Kholodov, V. N. and Butuzova, G. Y. (2008). Siderite formation and evolution of sedimentary
 iron ore deposition in the Earth’s history. Geology of Ore Deposits, 50, 4, pp. 299- 
 319. 
Kitson, A. E. (1928). Provisional Geological Map of the Gold Coast and Western Togoland,
 with Brief descriptive notes thereon. Gold Coast Geological Survey. Bulletin. 
Knoll, M. A. and James, W. C. (1987). Effects of advent and diversification of vascular lands
 plants on mineral weathering through geologic time. Geology, 15, pp. 1099-1102. 
Koehnken, L. (1990). The composition of fine-grained weathering products in a large tropical
 river system and the transport of metals in temperate estuary (Ph. D dissertation):
 Princeton University, Princeton, New Jersey, pp. 246. 
Koert, W. (1910). Begleit worte zur geologischer kante von Togo. In Hans Mayer’s Das
 Deutsche kolonia-ireich, Leipzig and Vienna, vol. 2.   
Krynine, P. D. (1936). Geomorphology and sedimentation in the humid tropics: American
 Journal of Science, 32, pp. 297-306. 
Kuenen, P. H. (1955). Experimental abrasion of pebbles 1. Wet sandblasting: Leidse
 Geologische Mededlingen. 20, pp. 142-147. 
Kuenen, P. H. (1956). Experimental abrasion of pebbles 2. Rolling by current: Journal of
 Geology, 64, pp. 336-368. 
Kuenen, P. H. (1962). Experimental abrasion 5. Frosting and defrosting of quartz grains:
 Journal of Geology, 70, pp. 648-658. 
Kuenen, P. H. (1964). Experimental abrasion 6. Surface action: Sedimentology, 3, pp. 29-43. 
Küster, D. and Liégeois, J. -P. (2001). Sr, Nd isotope and geochemistry of the Bayuda Desert
 high grade metamorphic basement (Sudan): an early Pan-African oceanic convergent
 margin, not the edge of the East Sahara ghost craton? Precambrian Research, 109, pp.
 1-23. 
Land, L. S. and Milliken, K. L. (1981). Feldspar diagenesis in the Fro Formation, Brazoria
 County, Texas Gulf Coast. Geology, 9, pp. 314-318. 
Leube, A., Hirdes, W., Mauer, R. and Kesse, G. O. (1990). The early Proterozoic Birimian
 Supergroup of Ghana and some aspects of its associated gold mineralization.
 Precambrian Research, 46, pp. 139-165. 
Li, Y. H. (2000). A Compendium of Geochemistry. Princeton University Press, Princeton, NJ,
 pp. 475. 
Mani, R. (1978). The geology of the Dahomeyan of Ghana; Geology of Ghana Project. Accra:
 Ghana Geological Survey Department. 
109 
 
University of Ghana http://ugspace.ug.edu.gh
Mann, W. R. and Cavaroc, V. V. (1973). Composition of sand released from three source areas
 under humid, low-relief weathering in the North Carolina piedmont. Journal of
 Sedimentary Petrology, 43, pp. 870-881. 
Manu, J., Asiedu, D. K. and Anani, C. Y. (2013). Geochemistry of Birimian phyllites from the
 Obuasi and Prestea Mines, Southwestern Ghana: Implications for provenance and
 source area weathering. International Journal of Basic and Applied Sciences, 2 (1), pp.
 12-19.  
Market, J. C. and Al-Sharieb, Z. (1984). Diagenesis and evolution of secondary porosity in
 Upper Minnelusa sandstones Powder River Basin, Wyoming. In: McDonald, D. A.
 and Surelam, R. C. eds., Clastic diagenesis: American Association of Petroleum
 Geologist Memoir, 37, pp. 367-389. 
Mast, M. A. and Drever, J. I. (1987). The effect of oxalate on the dilution rates of oligoclase
 and tremolite: Geochimica et Cosmochimica Acta., 51, pp. 2559-2568. 
Maynard, J. B., Valloni, R. and Yu, H. (1982). Composition of modern deep sea sands from
 arc related basins. Geological Society of London, Special Publication 10, pp. 551-561. 
Maynard, J. B., Sutton, S. J., Robb, l. J., Ferraz, M. F. and Meyer, F. M. (1995). A paleosol
 developed on hydrothermally altered granite from the hinterland of the Witwatersrand
 basin: Characteristics of a source of basin fill. Journal of Geology, 103, pp. 357-377. 
McCann, T. (1991). Petrological and geological determination of provenance in the southern
 Welsh Basin. In Morton, A. C., Todd, S. P. and Haughton, P. D. W. eds., Development
 in sedimentary provenance. Geological Society Special publication, 57, pp. 215 -
 230. 
McDaniel, D. K., Hemming, S. R., McLennan, S. M. and Hanson, G. N. (1994). Resetting of
 neodymium isotopes and redistribution of REEs during sedimentary processes: The
 early Proterozoic Chelmsford Formation, Sudbury Basin, Ontario, Canada.
 Geochimica et Cosmochimica Acta, 58, pp. 931-941. 
McDonald, D. A. and Surdam, R. C. (1984). Clastic diagenesis. American Association of
 Petroleum Geologists Memoir, 37, pp. 151-161. 
McLennan, S. M. (1989). Rare-earth element in sedimentary rocks: Influence of provenance
 and sedimentary processes. Mineralogical Society of America. Reviews in Mineralogy,
 21, pp. 169-200. 
McLennan, S. M., Taylor, S. R. and Eriksson, K. A. (1983). Geochemistry of Archean shales
 from the Pilbara super group Western Australia. Geochim. Cosmochim. Acta, 47, pp.
 121-1222. 
McLennan, S. M., Taylor, S. R. and McCulloch, M. T. (1990). Geochemical and Nd–Sr
 isotopic composition of deep-sea turbidites: crustal evolution and plate tectonic
 associations. Geochimica Cosmochimica Acta, 54, pp. 2015-2050. 
110 
 
University of Ghana http://ugspace.ug.edu.gh
McLennan, S. M. and Taylor, S. R. (1991). Sedimentary rocks and Crustal evolution: Tectonic
 setting and Secular trends. Journal of Geology, 99, pp. 1-21. 
McLennan, S. M., Hemming, S., McDaniel, D. K. and Hanson, G. N. (1993). Geochemical
 approaches to sedimentation, provenance and tectonics. In: Morton, A. C., Todd, S. P.
 and Haughton, P. D. W. eds., Development in sedimentary provenance. Geological
 Society Special Publication, 57, pp. 21-39. 
McLennan, S. M., Hemming, S. R., Taylor, S. R. and Eriksson, K. A. (1995). Early Proterozoic
 crustal evolution: Geochemical and Nd-Pb isotopic evidence from metasedimentary
 rocks, southern North America. Geochim. Cosmochim. Acta, 59, pp. 1153-1177. 
McDonald, D. A. and Surdam, R. C. (1984). Clastic diagenesis. American Association of
 Petroleum Geologists Memoir, 37, pp. 151-161. 
Middleburg, J. B., Van Der Weijen, C. H. and Woittiez, J. R. W. (1988). Chemical processes
 affecting the mobility of major, minor and trace elements during weathering of granitic
 rocks. Chemical Geology, 68, pp. 253-273.  
Middleton, G. V. (1960). Chemical composition of sandstones. Geol. Soc. America Bull., 71,
 pp. 1011-1026. 
Mielke, J. E. (1979). Composition of the Earth’s crust and distribution of the elements: Review
 of research on modern problems in geochemistry. International Association for
 Geochemistry and Cosmoschemistry. Earth Sciences, 16. 
Moncure, G. K., Lahann, R. W. and Siebert, R. M. (1984). Origin of secondary porosity and
 cement distribution in sandstones/shale sequence from the Frio Formation (Oligocene).
 In: McDonald, D. A. and Surdam, R. C. (1984). Clastic diagenesis. American
 Association of Petroleum Geologists Memoir, 37, pp. 151-161.  
Morad, S., Beyan, M., Knarud, R. and Nystuen, P. (1990). Albitization of detrital plagioclase
 in Triassic reservoir sandstone from the Snore field, Norwegian North Sea. Journal of
 Sedimentary Petrology, 60, pp. 411-425. 
Morton, A. C. (1984). Stability of detrital heavy minerals in Tertiary sandstones from the North
 Sea basin. Clay Minerals, 19, pp. 287-305. 
Morton, A.C. (1987). Influences of provenance and diagenesis on detrital garnet suites in the
 Forties sandstone, Paleocene, central North Sea. J. Sediment. Petrol. 57, pp. 1027 -
 1032. 
Nagarajan, R., Madhavaraju, J., Nagendra, R., Armstrong-Altrin, J. S. and Moutte, J. (2007).
 Geochemistry of Neoproterozoic shales of the Rabanpalli Formation, Bhima Basin,
 Northern Karnataka, southern India: implications for provenance and paleoredox
 conditions. Revista Mexicana de Ciencias Geológicas, 24, 2, pp. 150-160. 
111 
 
University of Ghana http://ugspace.ug.edu.gh
Nesbitt, H. W. (1979). Mobility and fractionation of rare-earth element during weathering of
 a granodiorite: Nature, 279, pp. 206-210. 
Nesbitt, H. W., Markovics, G. and Price, R. C. (1980). Chemical processes affecting alkalies
 and alkaline earths during continental weathering: Geochimica et Cosmochimica Acta,
 44, pp. 1659-1666. 
Nesbitt, H. W. and Young, G. M. (1982). Early Proterozoic climates and plate motions inferred
 from major element chemistry of lutites: Nature, 299, pp. 715-717. 
Nesbitt, H. W. and Young, G. M. (1984). Prediction of some weathering trends of plutonic and
 volcanic rocks based on thermodynamic and kinetic considerations: Geochimica et
 Cosmochimica Acta, 48, pp. 1523-1534. 
Nesbitt, H. W. and Young, G. M. (1989). Formation and diagenesis of weathering profiles:
 Journal of Geology, 97, pp. 129-147. 
Nesbitt, H. W., Young, G. M., McLennan, S.  M. and Keays, R. R. (1996). Effects of chemical
 weathering and sorting on the petrogenesis of siliciclastic sediments, with implications
 for provenance studies. Journal of Geology, 104, pp. 525-542. 
Nesbitt, H. W., Fedo, C. M. and Young, G. M. (1997). Quartz and feldspar stability, steady 
 state weathering and petrogenesis of siliciclastic sands and muds. Journal of Geology,
 105, pp. 173-191. 
Okada, H. (1971). Classification of sandstone: analysis and proposals. Journal of Geology, 79,
 pp. 509-525. 
Osae, O., Asiedu, D. K., Banoeng-Yakubo, B., Koeberl, C. and Dampare, S. B. (2006).
 Provenance and tectonic setting of Late Proterozoic Buem sandstones of southeastern
 Ghana: Evidence from geochemistry and detrital modes. Journal of African Earth
 Sciences, 44, pp. 85-96. 
Pettijohn, F. J. (1943). Archean sedimentation. Geol. Soc. America Bull., 54, pp. 925-97. 
Pettijohn, F. J. (1957). Sedimentary Rocks New York: Harper and Brothers, pp. 718. 
Pettijon, F. H., Potter, P. E. and Siever, R. (1972). Sand and sandstones. Springer-Verlag, New
 York. 
Pettijohn, F. J. (1975). Sedimentary Rocks. New York, Harper and Row, pp. 628. 
Pittman, E. D. (1970). Plagioclase feldspar as an indicator of provenance in sedimentary rocks.
 Journal of Petrology, 40, pp. 591-598. 
Plank, T. and Langmuir, C.H. (1996). EOS 1996 Fall Meeting Abstract. F 797. 
112 
 
University of Ghana http://ugspace.ug.edu.gh
Pober, E. and Faupl, P. (1988). The chemistry of detrital chromian spinels and its implications
 for the geodynamic evolution of the Eastern Alps. Geol. Rundsch., 77, pp. 641-670. 
Potter, P. E. (1978). Petrology and chemistry of modern big river sands. Journal of Geology,
 86, pp. 423-449. 
Potter, P. E. (2005). Provenance of Mudstones. In: Potter, P. E., Maynard, J. B. and Depetris,
 P. J. (eds), Mud and Mudstones: Introduction and Overview. Springer Berlin
 Hiedelberg, pp. 157-174. 
Potter, P. E., Heling, D., Shimp N. F. and Van Wie, W. (1975). Clay mineralogy of modem
 alluvial muds of the Mississippi River basin. Bull. Cent. Rech. Pau, 9, pp. 353 -
 389. 
Potter, P. E., Maynard, J. B. and Pryor, W. A. (1980). Sedimentology of shale. Springer
 Verlag. 
Roaldset, E. (1973). Rare earth element distributions in some Precambrian rocks and their
 phyllosilicates, Numedal, Norway. Geochim. Cosmochim. Acta, 39, pp. 455-469. 
Robertson, T. (1925).  The sedimentary and volcanic rocks of western Togoland. Geological
 Magazine, 62 (1), pp. 1-21. 
Roddaz, M., Viers, J., Brusset, S., Baby, P. and Herail, G. (2005). Sediment provenances and
 drainage evolution of the Neogene Amazonian foreland basin. Earth Planet. Sci. Lett.,
 239 (1/2), pp. 57-78. 
Roddaz, M., Viers, J., Brusset, S., Baby, P., Boucayrand, C. and Herail, G. (2006). Controls
 on weathering and provenance in the Amazonian foreland basin: insights from major
 and trace element geochemistry of Neogene Amazonian sediments. Chemical Geology,
 226 (1/2), pp. 31-65. 
Roddaz, M., Debat, P. and Nikiéma, S. (2007). Geochemistry of Upper Birimian sediments
 (major and trace elements and Nd–Sr isotopes) and implications for weathering and
 tectonic setting of the Late Paleoproterozoic crust. Precambrian Research 159, pp. 197
 - 211. 
Rollinson, H. R. (1993). Using geochemical data: Evaluation, Presentation, Interpretation.
 Longman, UK. pp. 352. 
Roques, M. (1948). Le Precambrian de L’ Afrique Occidentale Francaise, Bull. Geology
 Magazine, 62, pp. 589-628. 
Ronov, A .B., Balashov, Y. A. and Migdisov, A. A. (1967). Geochemistry of rare earths in the
 sedimentary cycle. Geochemistry International, 4, pp. 157-172. 
113 
 
University of Ghana http://ugspace.ug.edu.gh
Ronov, A. B., Balashov, Y. A., Girin, Y. P., Bratishko, R. K. H. and Kazakov, G. A. (1974).
 Regularities of rare earth element distribution in the sedimentary shell and in the crust
 of the earth. Sedimentology, 21, pp. 171-193. 
Ronov A. B., Migdisov A. A. and Lobach-Zhuchenko S. B. (1977). Regional metamorphism
 and sediment composition evolution. Geochemistry International, 14, pp. 90-112. 
Roser, B. P. and Korsch, R. J. (1986). Determination of tectonic setting of sandstone-mudstone
 suites using SiO2 content and K2O/Na2O ratio. Journal of Geology, 94, pp. 635-650. 
Roser, B. P. and Korsch, R. J. (1988). Provenance signatures of sandstone-mudstone suites
 determined using discriminant function analysis of major-element data. Chemical
 Geology, 67, pp. 119-139. 
Salomons, W. and Forstner, U. (1984). Metals in the Hydrocycle. Springer-Verlag. 
Santos, J. O. S., Hartmann, L. A., Gaudette, H. E., Groves, D. I., Mcnaughton, N. J. and
 Fletcher, I. R. (2000). A new understanding of the provinces of the Amazon craton
 based on integration of field mapping and U-Pb and Sm-Nd geochronology. Gondwana
 Research 3, 453-488. 
Scholle, P. A. and Schluger, P. R. (1979). Aspects of diagenesis: Society of Economic
 Paleontologist and Mineralogist Special Publication, 26, pp. 443. 
Schwab, F. L. (1975). Framework mineralogy and chemical composition of continental margin
 type sandstone. Geology, 3, pp. 487-490. 
Selley, R. C. (1982). An introduction to Sedimentology. New York, Academic Press, pp. 417. 
Shaw, D. M. (1968). A review of K-Rb fractionation trends by covariance analysis.
 Geochimica et Cosmochimica Acta, 32, pp. 573-602.  
Spiegel, C., Siebel, W., Frisch, W. and Zsolt, B. (2002). Nd and Sr isotopic ratios and trace
 element geochemistry of epidote from the Swiss Molasse Basin as provenance
 indicators: implications for the reconstruction of the exhumation history of the Central
 Alps. Chemical Geology, 189, pp. 231-250. 
Suttner, L. J. and Basu, A. (1981). Climate and the origin of quartz Arenites. Journal of
 Sedimentary Petrology, 51, pp. 1235-1246. 
Suttner, L. J. and Dutta, P. K. (1986). Alluvial sandstones composition and paleoclimate, I,
 framework mineralogy, Jour. Sed. Petrology, 56, pp. 329-345.  
Surdam, R. C., Boese, S. W. and Crossey, L. J. (1984). The chemistry of secondary porosity.
 In: McDonald, D. A. and Surelam, R. C. eds., Clastic diagenesis: American Association
 of Petroleum Geologists Memoir, 37, pp. 127-161. 
114 
 
University of Ghana http://ugspace.ug.edu.gh
Sylvester, P. J. and Attoh, K. (1992). Lithostratigraphy and composition of 2.1 Ga greenstone
 belts of the West African Craton and their bearing on crustal evolution and the Archean
 Proterozoic boundary. Journal of Geology 100, pp. 377-393. 
Tassinari, C. G., Bettencourt, J. S., Geraldes, M. C., Macambira, M. J. B. and Lafon, J. M.
 (2000). The Amazon craton. In: Cordani, U. G., Milani, E. J., Thomaz Filho, A.,
 Campos, D. A. (Eds.), Tectonic Evolution of South America. Brazil, 31st International
 Geological Congress, pp. 41-95. 
Taylor, S. R. and McLennan, S. M. (1985). The continental crust: its composition and
 evolution. Blackwell Science Publisher, pp. 312. 
Taylor, P. N., Moorbath, S., Leube, A. and Hirdes, W. (1992). Early Proterozoic crustal
 evolution in the Birimian of Ghana: constraints from geochronology and isotope
 geology. Precambrian Research, 56, pp. 97-111. 
Trompette, R. (1997). Neoproterozoic (600 Ma) aggregation of Western Gondwana: a tentative
 scenario. Precambrian Transactions of the Royal Society, London, Series A, 310, pp.
 54-590. 
Veizer, J. and Jansen, S. L. (1979). Basement and sedimentary recycling and continental
 evolution. Journal of Geology, 87, pp. 341-370.  
Veizer, J. and Jansen, S. L. (1985). Basement and sedimentary recycling-2: time dimension to
 global tectonics. Journal of Geology, 93, pp. 625-643. 
Velde, B. (1995). Origin and mineralogy of clays. Eds., Velde, B. Springer, Berlin, pp. 334. 
Villeneuve, M. and Cornée, J. J. (1994). Structure, evolution and paleogeography of the West
 African craton and bordering belts during the Neoproterozoic. Precambrian Research,
 69, pp. 307-326. 
Von Eynatten, H. (2003).  Petrography and chemistry of sandstones from the Swiss Molasse
 Basin: an archive of the Oligo-/Miocene evolution of the Central Alps. Sedimentology
 50, pp. 703 – 725.  
Von Eynatten, H. and Gaupp, R. (1999). Provenance of Cretaceous synorogenic sandstones in
 the Eastern Alps: constraints from framework petrography, heavy mineral analysis, and
 mineral chemistry. Sedimentary Geology, 124, pp. 81-111. 
Von Eynatten, H. and Wijbrans, J.R. (2003). Precise tracing of exhumation and provenance
 using Ar/Ar-geochronology of detrital white mica: the example of the Central Alps.
 Spec. Publ. Geol. Soc. London, 208, pp. 289-305. 
Von Eynatten, H., Gaupp, R. and Wijbrans, J. R. (1996). 40Ar/39Ar laser-probe dating of
 detrital white micas from Cretaceous sedimentary rocks of the Eastern Alps: Evidence
 for Variscan high-pressure metamorphism and implications for Alpine orogeny.
 Geology, 24, pp. 691-694. 
115 
 
University of Ghana http://ugspace.ug.edu.gh
Weaver, C. E. (1989). Clays, Muds, and Shales. Elsevier. 
Wedepohl, K. W. (1978). Handbook of Geochemistry. Berlin, Springer-Verlag. 
Wintsch, R. P. and Kvale, C. M. (1994). Differential mobility of elements in burial diagenesis
 of siliciclastic rocks. Jorunal of Sedimentary Research, A64, pp. 349-361. 
Whetten, J. T., Kelley, J. C. and Hans, L. G. (1969). Characteristic of Columbia River sediment
 and sediments transport. Journal of Sedimentary Petrology, 39, pp. 1149-1166. 
Woolnough, W. G. (1930). The influence of climate and topography in the formation and
 distribution of products of weathering: Geological magazine, 67, pp. 123-132. 
Wrafter, J. P. and Graham, J. R. (1989). Ophiolitic detritus in the Ordovician sediments of
 South Mayo Ireland. Journal Geological Society of London, Vol. 146, pp. 213-215. 
Wright, J., Hastings, D., Jones, W. and Williams, H. (1985). Geology and Mineral Resources
 of West Africa. London: George Allen and Unwin publishers Ltd. 
Wronkiewicz, D. J. and Condie, K. C. (1987). Geochemistry of Archean shales from the
 Witwatersrand Supergroup, South Africa: Source area weathering and provenance.
 Geochimica et Cosmochimica Acta, 51, pp. 2401-2416. 
Wronkiewicz, D. J. and Condie, K. C. (1990). Geochemistry and mineralogy of sediments
 from the Ventersdorp and Transvaal Supergroups, South Africa: Cratonic evolution
 during the early Proterozoic. Geochimica et Cosmochimica Acta, 54(2), pp. 343-354. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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APPENDIX 
 
LIST OF SAMPLE LOCATIONS 
Sample station Latitude (N/degree) Longitude (W/degree) 
KP1 5.80025 -0.18419 
KP2 5.800083 -0.1845 
KP3 5.799083 -0.18469 
KP4 5.798944 -0.18422 
KP5 5.795417 -0.18428 
KP6 5.795222 -0.18467 
KP7 5.79475 -0.18603 
KP8 5.79475 -0.18672 
KP9 5.793861 -0.18647 
KP10 5.792778 -0.18647 
KP11 5.788861 -0.18617 
KP12 5.788889 -0.18578 
KP13 5.788806 -0.18536 
KP14 5.766417 -0.19664 
KP15 5.768 -0.19514 
KP16 5.792139 -0.18447 
KP17 5.786611 -0.20775 
KP18 5.779000 -0.186000 
KP19 5.776000 -0.190000 
NP11 5.780000 -0.187000 
NP12 5.779000 -0.186000 
NP13 5.777000 -0.186000 
 
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