Sand bodies and incised valleys within the Late Quaternary Sanaga–Nyong delta complex on the middle continental shelf of Cameroon |
| |
| Authors: | Gabriel Ngueutchoua Pierre Giresse |
| |
| Institution: | 1. Département de Géologie, Université de Yaoundé I, Cameroon;2. IMAGES EA4218, Laboratoire d’Études des Géo-Environnements marins, Université de Perpignan, 52 Avenue Paul Alduy, 66850 Perpignan Cedex, France |
| |
| Abstract: | Seismic data and sediment cores collected offshore from the Sanaga River and Nyong River mouths were used to analyse a loose mantle of yellow to reddish sandy gravel with a range of fluvial and deltaic characteristics cropping out in the middle part (25–65 m water depth) of the continental shelf of Cameroon. Contrary to most of the Atlantic shelves, where the lowstand systems tract was destroyed by erosion, we found 80–120 ms (60–90 m) of sediment mainly in the middle part of the shelf, which correspond credibly to MIS 2–4. Fluvial paleodrainage systems are preserved beneath the shelf and individual filled channels with planar infillings were mapped that cross the shelf along two surfaces of erosion. These incisions suggested westerly and northwesterly drainage shifts during presumed lowered base level. The presence of closely spaced channel fills suggests repeated avulsion of a single stream during a long-lasting sub-aerial erosion period. The seismic facies of these Pleistocene deposits distinguish themselves clearly from well-stratified older strata showing deformation (Pliocene) or intense folding (Miocene). The orientation of the paleovalleys appears strongly controlled by the N60°E trending cross faults within Mesozoic–Cenozoic strata. |
| |
| Keywords: | Cameroon shelf Late Quaternary Incised valley Sand bodies |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
