Abstract:

The major petroliferous basins along Wes tAfrican coastline are typical superimposed basins of continental rift basins and passive continent almargin basins，therefore sharing the same regional tectonic evolution background. However，due to the difference of plate evolution process between the south and north parts of the West African coast，the basins vary in their form ing times，tectonic evolution characteristics，and deposition features，causing the basins in the south part significantly differs from that in the north in geological conditions，accumulation patterns and hydrocarbon abundance. The formation of basins in the north part is mainly connected with the breakup of the North Atlantic and the separation of the African from the North American plate. The structural evolution of North African also contributes to the formation of these basins. In the early stage of basin evolution，tectonic differentiation was strong and no unified depocenter formed. While in the late stage，the basins down warped as a whole and were influenced by the Atlas Orogeny. As a result，they vary greatly in height differences and their sedimentary thickness quickly thickens seaward. The formation of basins in the south and middle parts is chiefly related to the formation of South Atlantic and the separation of the African plate from the South American plates. In the early stage of basin evolution，a unified basin with similar sedimentary sequence and strata characters formed and its depocenter was located in central Gabon and lower Gongo basin. In the Tertiary，the unified basin began to differentiate and formed a series of delta and fanˉdelta depositional systems along the West African coast，such as the Niger delta basin and the Congo fan basin. However，the size or scale of these systems decreases progressively from north to south. This article is focused on the formation and evolution of the major petroliferous basins in the area and their controlling effects over the hydrocarbon accumulation. The comparative study can be used as a guide to screening of strategic petroleum provinces in West Africa.

Key words: hydrocarbon accumulation, evolutionary characteristic, petroliferous basin, West African coast