Lower Tertiary foraminifera from subsurface sediments in the Calabar flank, S.E. Nigeria. – O. A. Njoh, U. U. Nkeme and S. W. Petters
The Calabar Flank has erroneously been considered and treated as an exclusive Cretaceous sedimentary basin. A recent examination of some sections in the Uruan–1 and Ikono-1 wells respectively on the eastern edge of the basin have revealed a lower Tertiary Foraminifera assemblage which do not only characterize the lower Tertiary, but permitted the recognition of the Paleocene and Eocene ages. This foraminiferal assemblage is fairly abundant, diverse and consists of both the benthonic and planktonic forms. The planktonics are dominated by the acarininids and morozovellids and also some diagnostic forms like Morozovella angulata (White), Morozovella acuta (Toulmin), Subbotina triloculinoides (Plummer), Acarinina aequa (Cushman and Renz), Acarinina soldadoensis-soldadoensis, (Bronnimann), Pseudohastigerina wilcoxensis (Cushman and Ponton), Planorotalites pseudomenardii (Bolli) Chiloguembelina wilcoxensis (Loeblich and Tappan). The benthonics include among others, Anomalinoides midwayensis, Eponides pseudoelevatus, Bullimina midwayensis, Bolivina africana, Hopkinsina danvillensis, Gyroidinoides sp, and Anomalinoides umboniferus. This benthic assemblage generally correlates with the lower Tertiary. Therefore unlike thought previously the sediments studied here confirmed that the lower Tertiary interval do occur in the Calabar Flank. However, it is suggested that the sediments may be the relicts of the massive post-Cretaceous erosional episodes which were widely reported in this region.