Seismic Geomorphology of a Late Cretaceous Turbidite Channel system in Deepwater Kribi/Campo sub-basin, offshore Cameroon

Abstract

In this study, a seismic reflection dataset and well-log data were integrated to investigate the geometry and internal configuration of a turbidite channel system within the Late Cretaceous interval of the deep-water Kribi-Campo sub-basin, offshore Cameroon. This interval is characterized by a well-developed submarine channel system consisting of an early and a late-stage channel. Morphologically, the submarine channel system has a northeast-southwest trend and is U-shaped in cross-section with a length of 56 km within the study area. The early-stage channel has a relatively straight morphology and varies in width and depth from 3 to 5 km and 89 to 197 m, respectively. However, the late stage of the channel is characterized by a narrower (1 to 3 km) and shallower (41 to 103 m) incision, with sinuous morphology carved into the early channel infill. The changing interaction of differential tectonic subsidence, relative sea level, source sediment supply and slope gradient change are considered to be the major control on the geometry and internal characteristics of the submarine channel system. Sag subsidence during the Campanian led to basin deepening and the widespread development of basinal sediments as submarine fans and promotion of submarine channel system development. The filling of the channel system occurred during a long-term Maastrichtian relative sea level rise, punctuated by falls in relative sea level. Sand appears to have been fed to the channel system by the palaeo-Sanaga and palaeo-Nyong Rivers, with sand rich aprons developed were these rivers debouched into the study area. The early stage of the submarine channel is dominated by coarse-grained sediments in the southwest and fine-grained sediments in the northeast, while the late-stage channel is mainly filled with fine-grained sediments. The presence of coarse-grained sediments occur within the submarine channel axis downstream represents a potential for hydrocarbon reservoirs with enhanced petrophysical qualities due to a low depositional gradient. The geomorphological analysis of this ancient submarine channel system along the western African margin, as presented in this study, has broad implications in the understanding of the distribution of deep-water sediments with potential for hydrocarbon exploration in the region.