Controle litológico sobre índices de meteorização química: um caso de estudo com sedimentos atuais do SW de Angola

Abstract

Different compositional features of sedimentary units have been used to evaluate the intensity of chemical weathering. In this work we used the geochemistry and clay mineralogy of a set of present-day sediments collected in the lithologically and geomorphologically heterogenous Caculuvar- Mucope fluvial system to investigate the processes that influence weathering proxies. Weathering proxies measured in deposits of different grain-size are not coincident. Sand is too affected by provenance to provide safe information about weathering intensity. Fine-grained deposits still hold a lithological signal but are much more affected by chemical decomposition. Robust relations between weathering and clay assemblages can only be obtained if reworking processes are not involved in sediment production