TITLE:
Characterization of Bentic Microfauna of the Maastrichtian Deposits of EB-1 Well, Ivory Coast Onshore Basin
AUTHORS:
Larissa Chiaye Koffi Epse Coulibaly, Leger Kouame Djeya, Veronique Attabla Konan, Kader Bamba, Sylvain Monde
KEYWORDS:
Foraminifera, Lithology, Paleoenvironment, Maastrichtian, Ivory Coast Basin
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.7,
July
21,
2026
ABSTRACT: This study focuses on the characterization of the benthic microfauna from 19 drill cuttings samples from the EB-1 oil well, located in the onshore part of the Ivory Coast basin. The main objective is to reconstruct the depositional environment and establish the lithostratigraphy of the Maastrichtian sediments. The studied lithological profile (between 201 m and 120.5 m in the direction of sedimentation) is divided into three main units: Unit A (Base) is essentially composed of fossiliferous limestone. Unit B (Middle) is an alternation of clays and fine to coarse sands, and finally, Unit C (Top) is an alternation of sand and kaolinite. Biostratigraphic and microfaunal analysis revealed a rich (3241 individuals) but not very diverse microfauna, dominated at 84.49% by benthic foraminifera. The genera Praebulimina, Orthokarstenia, and Afrobolivina predominate. However, there is a low presence of planktonic foraminifera (Planoheterohelix, Rugoglobigerina). The combined analysis of lithological data and the pelagism index allows for the reconstruction of the depositional environment. This is a medium-depth, internal platform environment (estimated depth between 10 and 100 meters) which suggests ecological conditions characterized by a high proliferation of Bolivinidae and Buliminidae, associated with low species diversity, indicating anoxic conditions (oxygen-poor environment) and an abundance of organic matter. This work confirms the Maastrichtian age of the EB-1 well deposits and highlights a shallow marine environment, marked by sea-level fluctuations and episodes of oxygen deficiency.