Palynological insights into paleoenvironmental and paleoclimatic reconstruction of the BW–001 well, Dahomey basin, Nigeria

Abstract

Major palynological abundance and diversity changes provide valuable tools for reconstructing paleoenvironmental and paleoclimatic conditions in sedimentary basins. This study investigates lithological and palynological characteristics of the BW–001 well in the Dahomey Basin, southwestern Nigeria, to establish its age framework, define palynozones, and infer depositional and climatic history. Thirty ditch-cutting samples were analyzed using standard laboratory preparation techniques for both lithological and palynological characteristics. Lithology is dominated by shales and sandy shales. Palynomorph assemblages include diverse marine dinoflagellate cysts (Apectodinium, Senegalinium, Nematosphaeropsis, Subtilisphaera, Lejeunecysta, Homotryblium, Operculodinium, Lingulodinium, Spiniferites) and terrestrial pollen and spores (Cyathidites, Retibrevitricolporites triangulatus, Longapertites, Proxapertites cursus, Spinizonocolpites echinatus). Five palynozones were recognized: K1 (Late Cretaceous, Maastrichtian), T1 (Early Paleocene, Danian), T2 (Late Paleocene, Thanetian), T3 (Early Eocene, Ypresian), and T4 (Early–Late Eocene, Ypresian–Priabonian), spanning the Maastrichtian to Priabonian interval. Persistent wet-climate indicators and the peak abundance of Apectodinium between 7620–7860 ft linked to Paleocene–Eocene Thermal Maximum (PETM) local event and Paleogene greenhouse conditions characterized by warm, humid environments. The BW–001 well records deltaic to marginal marine depositional settings and provides evidence of tropical paleoclimate signals during the Late Cretaceous–Eocene. These findings may contribute to regional stratigraphic frameworks and enhance understanding of West African paleoclimate evolution.