Palyno-environmental study of the Araromi-1 Well, eastern Dahomey Basin, south-west Nigeria

Abstract

The exploration of many inland basins in Nigeria for their hydrocarbon potential is important to maintain her position in
the global world oil market. A total of 23 core samples extracted from Araromi-1 Well, Eastern Dahomey Basin, south-west
Nigeria, were carefully studied through lithostratigraphy and palynology with a view to determining the lithological
sequence, relative age, palynological zone and paleo-environments of deposition. The lithological characterisation revealed
a wholly shale unit with thin layer of clay towards the top of the well. A total of 58 palynomorphs were recovered and this
indicates well preserved samples with abundant and highly diverse pollen, spores and dinoflagellate cysts. The microfloral
assemblages include abundant zonocostites ramonae, monoporites annulatus, retitricolporites irregularis, monocolpites
marginatus, acrostichum aureum, cyathidites minor, cyathidites sp, laevigatosporites sp and proxapertites cursus.
Abundant quantities of dinoflagellate cysts particularly palaeocystodinium australinium, cerodinium diebeli,
leiosphaeridia sp, palaeocystodinium sp, seleiropemphix homotryblium oceaniclum, odontochitina operculata,
achromorphaera ramulifera and spiniferites sp. were recovered. Common deep water indicator, microforaminiferal wall
linings was also recorded. The well falls within just a zone, P100 to P200, characterized by the occurrence of paleocystodium
australinium, cerodinium diebeli and odontochitina operculata dated Late Maastrichtian to Late Paleocene.
Paleoenvironmental deductions were based on the relative abundance of freshwater swamps pollen and spores, diagnostic
dinoflagellate cysts and deep marine indicator inferring brackish to deep marine setting.