Biostratigraphy and Palaeoecological Studies of the Late Cretaceous-Tertiary Sediments in the Dahomey Basin, Nigeria

The Maastrichtian–Eocene sediments (mainly shales and limestones) penetrated by the Itori borehole Ilaro boreholes in Dahomey Basin were investigated for foraminiferal biostratigraphy palaeoecological interpretation. These Araromi, Ewekoro, Oshosun formations at varying depths. Selected shale subjected to analysis many planktonic benthic species of foraminifera (agglutinated calcareous) recovered from Cretaceous interval boreholes. Twelve planktic (Globalomalina planocompressa, G. pseudomenardii, Globigerina inaequispira, Acarinina cf.coalingenis, nitida, Chiloguembelina cretacea, chiloguembelina subtriangularis, Orthokasrstenia sp., Hedbergella holmdelensis, Globigerinelloids asperus, Morozovella formosa formosa) thirteen i.e Bolivina B. Crassicostata, , E. africana, Eponides psuedoelevatus, Gavelinella cf. guineana, pachysuturalis, Haplophragmiodes Lenticulina cyprina, L. inornata, olokuni, psuedomamilligera, taylorensis, Nonionella communis, N. spissa, panamensis, Orthokarstenia Planulina oyae) identified. In general, infauna deposit feeder epifauna dominate population. occupy a range environments dyoxic anoxic, brackish water marsh environment down upper bathyal depth. Based on abundant stratigraphical distribution species, four biostratigraphic zones recognized: Afrobolivina afra zone late Maastrichtian, early Paleocene, Globalomalina pseudomenardii Paleocene Eocene.