Mesozoic-Cenozoic history of the Congo Basin

The geometry of the continental Mesozoic and Cenozoic deposits begins with beds overlying a widespread planation level unconformity and/or the presence of gravel or conglomerate in the lower portion. The Sables Ocres Series and the Grès Polymorphes Series rest on the planation levels of Late Cretaceous and mid-Tertiary ages respectively. Mechanical composition and morphoscopic characters argue for a dominant eolian transport for the Grès Polymorphes and for a fluvial deposition for the Sables Ocres. The silicification process achieves its maximum extent during the Paleogene interval characterised by a micaceous mineral rich clay fraction in the Congo basin sediments. This process stopped at the beginning of the Neogene interval when the kaolinitic component increased significantly.