Depositional environments reflected by benthic foraminifera in the lower cretaceous reservoir section of Southern Pletmos Basin, South Africa

Abstract

The Pletmos Basin is one of the several exploratory basins situated along the southern continental margin of South Africa characterized by Lower Cretaceous marine clastic successions influenced by syn-sedimentary tectonic activities. There is still paucity in the understanding of the paleoenvironment of the southern Pletmos Basin off-shore South Africa. Hence this study is the analysis of 38 drill core samples from a high-resolution biostratigraphic study of the reservoir section in an exploratory well within the southern Pletmos Basin. The recovered highly diverse benthic foraminiferal assemblage is dominated by calcareous taxa. The temporal distribution of the foraminiferal assemblages indicates shelf sedimentation with minor shallowing at certain reservoir intervals resulted in the deposition of relatively clean sands. Frequency and diversity of the taxa were found to be moderate throughout the studied interval. Mainly fine sands and siltstones constitute the reservoir in this locality. This study is significant because understanding of benthic foraminiferal assemblages in this interval directly addresses key uncertainties in the reservoir's distribution, paleodepth of deposition, stratigraphic architecture, and basin evolution, thereby enhancing the petroleum-system evaluation and reducing exploration risk in this underexplored offshore basin.