Congo Fan Neogene and Quaternary Sedimentation: Interplay of Riverine and Current Induced Deposition
The incorporation of information regarding sedimentation rates and lithology from ODP Leg 175 Sites 1075, 1076 and 1077 into the analysis and interpretation of high-resolution seismic reflection data led to the revision and refinement of a depositional model for the upper Congo Fan area presented earlier by Uenzelmann-Neben (1998). The main sediment contributor to the upper fan was determined for four time slices since the Eocene (Late Oligocene - Miocene/Pliocene, Pliocene - 600 ky, 600 ky - ~160 ky, ~160 ky - Recent). Thus we can say that input of sediments from the north dominated the area in the Late Paleogene by either a south setting current or the Kouilou/Niari River. This situation continued to the period Pliocene - 600 ky when southern sediment sources (the Congo River and upwelling) became dominant, with the material being deflected to the north by the Benguela Current. As a sediment source on the upper fan, upwelling became even more important after 600 ky while the main sediment load of the Congo River is guided to the middle and lower fan via the Congo Canyon.