Shallow Marine Cenomanian-Turonian Benthic Foraminifera and Kerogen Type from Mangoule, Logbadjeck Formation, Douala/Kribi-Campo Basin, Cameroon, West Africa

Abstract

An integrated benthic foraminiferal and organic matter analysis of samples obtained from sedimentary sections exposed in the Mangoule-Bonepoupa area, revealed a very shallow marine paleo-depositional environment for the sediments studied, with considerable influx of continental organic matter that were accumulated during the Cenomanian-Turonian age. With reference to the lithostratigraphic profile of the Douala/Kribi-Campo Basin, the age obtained reveals that the sedimentary sections studied belong particularly to the lower section of the Logbadjeck/Mungo River Formation, based on the following benthic foraminifera assemblage: Ammobaculites jessensis, Ammobaculites benuensis, Ammobaculites coprolithiformis, Ammotium cf nkalagum, Ammotium nwalum, Haplophragmoides cf beuchensis, Trochamina taylorana. A particularly very poor palynomorph assemblage was recovered and included no age diagnostic species: Acrostichum aureum, Lycopodiumsporites sp., Fungal spore, Lavigatosporites discordatus, Longapertites sp., Verrucosisporites sp. An organic petrographic analysis performed on these samples revealed Kerogen Type-II and Type-III. The entire data sets obtained from this area is remarkably poor and we suspect poor preservation as the cause viewing the extent of weathering. The paleo-depositional environment of these sediments was suggested both from the foraminifera and palynomorphs present and confirmed from the organic matter types and macrofossil contents. The studied sections are composed generally of dark to dark-gray shale beds. As one of the petroleum producing basins within the Gulf of Guinea in which exploration/exploitation activities are on-going, the current research is aim at providing more data useful in the continuous search for more potential source rocks in this basin.