New Organic Matter Characterisation and Paleodepositional Conditions of the Lower Cretaceous Lacustrine Shale in the Synrift Basin (Babouri–Figuil Basin, North Cameroon): Implication for Petroleum Exploration

Abstract

The synrift basins of the West and Central African Rift System (WCARS) contain Lower Cretaceous lacustrine shale, which is considered to be the main source rock of hydrocarbons that accumulated in these basins. Recent studies of these lacustrine shales do not consider the diversity of organic-rich lithofacies within these basins. This study aims to investigate Lower Cretaceous organic-rich facies in the Babouri–Figuil Basin, part of the WCARS. The samples collected (n = 173) were subjected to bulk geochemical and elemental analyses and organic petrological observations. Oil shales exhibit a higher average total organic carbon (TOC) value of 17 wt%, whereas the associated facies contain less than 2 wt% TOC. The oil shales display an average hydrogen index (HI) value of 769 mg HC/g TOC. However, the associated facies generally exhibit HI values below 300 mg HC/g TOC. Oil shales and associated facies contain well-preserved kerogen, ranging from Types I to III, indicating good to very good potential for hydrocarbon generation. Rock-Eval pyrolysis reveals relatively similar thermal maturity across the studied organic-rich facies, with an average T_max value of 430°C, displaying an immature to early oil window stage of maturation. These results suggest that the WCARS basins generally hold promise for further petroleum exploration efforts.

Keywords

hydrocarbon generative potential / oil shale / organic petrology / palynofacies / petroleum source rocks / Rock-Eval pyrolysis

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2026 Geological Society of China.