Biostratigraphy Of The Upper Tertiary Western Offshore Niger Delta Nigeria

Abstract In this studies Stratigraphical and taxonomic studies are made of the arenaceous and calcareous as well as planktonic foraminifera of the Middle Miocene - Pleistocene strata of part western offshore Niger delta. Forty one genera comprising ninety- six species have been identified from seventy- eight borehole samples. The species are composed of calcareous foraminifera typified by the Mililoides Buliminids Rotalids Orbitoids and planktonic forms. The arenaceous are typified by the Lituolids and they constitute the major fauna. The assemblages suggest that the strata containing them were deposited in a littoral to outer nentic environment in an area that was exposed periodically to the sea as evidenced by the foraminifera fauna assemblage. The studied is assigned a middle Miocene to Pleistocene age based on the presence of orbulina universa and Sphaeroidinella dehisceus. The abrupt break in the benthonic and planktonic foraminifera in the upper part of the well also marks the Pliocence - Pleistocene boundary.