La cuirasse ferrugineuse conglomératique de Cabatuquila (Malanje - R. P. d'Angola) et sa signification paléogéographique

Abstract

Key-words: Cassanje escarpment - Conglomerate ferricrete - Plio-Pleistocene. Cabatuquila conglomerate ferricrete (Malan je Province, located North Central Angola) corresponds to a thick (1O-15m) and hardcornice at the topof"Baixa de Cassanje"escarpment. "Baixa de Cassanje" is a large graben part of South Congo basin. Cabatuquila conglomerate ferricrete seems to correspond to a Plio-Pleistocene morphology which has already disappeared. Laterization dynamics and ferricrete formation processes took place on the Tertiary surface, before being tilted to the Congo Basin. Materials submitted to these processes are mainly alluvial deposits from a pre-Cuanza drainage system. This drainage system flowed to the North before being captured to the Atlantic, as a consequence of the movement which deformed the Tertiary surface during the Pleistocene. The erosion dynamics, which created the Cassanje depression, has occurred after the late Tertiary surface deformation. That dynamics might be related to the Cuango drainage system, which was reorganized after that deformation.