Abstract:
Miospores and dinoflagellates recovered from sediments from the ST – 5 and ST – 6
wells, offshore Tano Basin, Western Ghana were studied in order to determine their
ages, establish palynostratigraphy and determine environments of deposition. Based on
First Appearance Datum (FAD) and (LAD) of marker palynomorphs, three (3) biozones
were erected for miospores and dinoflagellates respectively. The characteristic taxa of
each of the biozones have been discussed in detail. The three biozones correspond to
an Albian-Cenomanian, Campanian-Maastrichtian and a Paleocene age respectively.
There are no representatives of the Turonian/Santonian ages, thus suggesting the
presence of an unconformity between the Albian–Cenomanian and Campanian-
Maastrichtian sediments. The Albian–Cenomanian sediments are characterised by the
presence of elaterate pollen with scarce dinoflagellates which is indicative of deposition
in a marginal marine environment under a warm, arid/semi-arid climate. The
Campanian–Maastrichtian sediments are characterized by typical Nypa species such as
Proxapertites and Longapertites that thrived in a coastal mangrove environment under
a hot tropical to sub-tropical climate. The dinoflagellates of the Campanian–
Maastrichtian sediments indicate that deposition took place in a marginal marine to
open marine environment. These conditions were deduced based on the variations in
the relative abundance of peridiniacean to gonyaulacoid cysts. The peridiniacean
assemblage observed in the Campanian–Maastrichtian sediments of the ST–5 and ST–
6 wells of the Tano basin is dominated by Andalusiella, Cerodinium, Senegalinium and
Phelodinium. These species are the constituents of the tropical – subtropical Malloy
suite of Lentin and Williams (1980). The miospore assemblage of the Albian–
Cenomanian horizons shows elements that are typical of the Albian-Cenomanian
Elaterate Province of Africa and South America. The Campanian – Maastrichtian
miospore assemblage observed are also typical of the Senonian Palmae Province.
