Authors : Edwin Ayuk Ndip, Christopher M. Agyingi, Matthew E. Nton and Michael A. Oladunjoye
Abstract: The organic-rich shale of the Lower Cretaceous Mamfe Formation is considered as an importantpetroleum source rock in the Mamfe Basin. Biomarker geochemistry of the shales was carriedout to evaluate the source of the organic matter input, paleoenvironmental conditions andthermal maturity. The investigated biomarker indicated that the Mamfe sediments containterrigenous organic matter with marine and lacustrine influences. The Pr/Ph ratio that ranged from 0.60-1.71 and the Gammacerane index of 0.07-0.23 are indicating sub-oxic torelatively anoxic preservation of the organic matter. Biomarker data revealed that C29 steranes (32.0-43.0 %) are relatively more abundant than the C27 (30.0-39.0%) and C28 (27.0-33.0%) steranes in the analysed shale extracts which imply a substantial contribution of landplant derived organic matter. The Oleanane index of 0.10-0.23 supports a predominance ofterrigenous organic matter source in the sediments. Carbon Preference Index of 1.0, Trisnorneohopane/Trisnorhopane (Ts/Tm) ratio ranging from 0.33-0.63 and Moretane/Hopane(M/H) ratio ranging from 0.16-0.27 showed that the shale’s are thermally mature with respectto hydrocarbon generation.
Edwin Ayuk Ndip, Christopher M. Agyingi, Matthew E. Nton and Michael A. Oladunjoye, 2020. Biomarker Geochemistry of the Lower Cretaceous Mamfe Formation Shale, Mamfe Basin, Cameroon: Implications for Organic Matter Origin, Paleoenvironmental Conditions and Thermal Maturity. Online Journal of Earth Sciences, 14: 32-38.