Regularities and geohistorical prerequisites of oil and gas specialization of rift sedimentary basins of Africa

Sedimentary basins of Late Phanerozoic rift origin are located in Africa and on its underwater margins. The reasons for the oil and gas specialization of basins of this class remain largely unclear. Patterns have been identified that could be of decisive importance in this regard. The intracontinental basins are characterized almost exclusively by oil deposits. In the pericontinental basins, the value of gas deposits decreased, and oil increased in accordance with the decrease in the time of their reef laying and deflection (from C3, P-J1, K1 to J5-K12). The differentiation of basins into tectonotypes of “incomplete” and “completed” development, as well as the asynchronous deflection of the latter reflected in their oil and gas specialization, correlate accordingly with the size and age of the Pan-African granulite belts in which the basins were laid. Since these belts were the most active core structures, this pattern can be considered as evidence of the influence of their inherited or reborn deep “energy systems” on the processes of rifting and generation of hydrocarbons. The use of seismography data showed that mainly oil and gas-bearing rift basins are located in areas of less and more heated mantle respectively. An example of the probable influence of Cenozoic island volcanism centers on oil and gas basin systems is given. A comparative analysis of geological and geophysical data, including heat flows, leads to the conclusion that the temperature conditions of hydrocarbon formation in the rift basins of Africa were determined by a combination of deep thermal systems of different scales: regional (continent - ocean), subregional (cow-structural) and local (volcanic centers).