Tectonic evolution of East Africa coast and comparison of hydrocarbon accumulation conditions in the north and south petroliferous basins

The major petroliferous basins along East African coast are the “rift depression type” basins filled by the superimposed rift depression sequence and passive continental margin sequence, with the breakup of the Gondwana and the opening up of the Neotethys. The tectonic evolution of these basins can be subdivided into three distinct pulses: Karoo intercontinental rifting, Madagascar drifting and the evolution of a passive continental margin. However, the basins in the south part differ significantly from that in the north in tectonic and sedimentary characteristics, petroleum geological conditions and hydrocarbon distribution patterns. During the transgression of the Tethys Ocean in Early Jurassic, the northern basins were prevailed by lagoonal salt rock and shallow marine shale, while the southern basins was suffered from intense volcanic eruption. The hydrocarbon accumulation is also very different in the two basins. For examples, the source-reservoir-cap assemblages become younger from north to south and the northern basins are much richer in oil and gas resources. The preliminary analysis suggests that the difference in tectonic environments control the development of source rocks, and the traps formed by fractures and plastic rocks.