A comparative study of tectonic and sedimentary evolution of West African coastal basins in the south Atlantic Ocean region

Basins along West African coast have certain similarities in structure and evolution since they have all experienced prerift, rift and drift period, but there also exist differences in present tectonic and sedimentary patterns due to the influence of local events, which leads to different exploration results. In order to summarize characteristics of these basins, the authors compared the comprehensive lithologic column diagrams and restored balanced cross-sections of Niger delta basin and lower Congo basin. The results are as follows. 1) Basins in the equatorial segment have transferred from continental facies such as lacustrine facies and fluvial facies to neritic facies, and there exist no salt deposits in this kind of basins. 2) Niger delta basin is characterized by thick Cenozoic Akata Formation, which is a detachment layer and has been deformed under differential load. 3) The salt-bearing basins in central segment experienced a transition period in Aptian stage, within which sedimentary environment transferred from continent to marine environment. The Aptian salt rocks migrated under the differential load and gravity slippage and divided whole basin into three domains, i.e., extensional domain, salt diapir and contractional domain. 4) The volcanic type in the southern segment is characterized by intense volcanism and extensive development of SDRs.