Fossils Dino agellates from the Northern Border of the Douala Sedimentary Sub-Basin (South-West Cameroon): Age Assessment and Paleoecological Interpretations

The deposits of the Douala sub-basin stand among the Gulf of guinea best-studies series. In spite of continuous oil prospecting production in the area, there is still a paucity of published information and data on the palynology of the Douala sub-basin. This study aimed at reconstructing the palaeoenvironments from dinoflagellates cysts identified in surface samples collected among deposits of the Nkappa formation. Ten surface samples from three different localities (Miang, Fiko and Bwapaki) were collected, studied and analyzed for their lithological and palynological contents. This essentially comprised the field description of lithological and textural characteristics of facies. The laboratory work was based on treatment and extraction of dinoflagellates cysts from shales samples selected for the study, using the standard palynological method applied in the laboratory of micropaleontology of PETROCI (Ivory Coast). Hence, four lithological units were delineated made up of dark to grayish shales, fine, medium and coarse sandstones. A total of sixteen dinoflagellates cysts were recovered and identified from the samples. They all belong to the class Dinophyceae but are subdivided into four families (Gonyaulacaceae, Peridiniaceae, Areoligeraceae and Protoperidiniaceae). The dominant dinocysts grains are those of Areoligera sp, glaphyrocysta sp, Paleocystodinium golzowense and Cerodinium sp. Correlation with other studies carried in the neighbouring basin and event over the world allow giving a Maastrichtian-Paleocene age to the formation studied. Palaeoecological interpretations from the above data suggest of shallow marine coastal environments where waters are warm and have a normal salinity.