The Mesozoic West and Central African Rift System
J. D. Fairhead
GETECH, Leeds, United Kingdom
Africa underwent a series of rifting phases as Gondwana fragmented. The Mesozoic basins of central Africa form a network of passive rift basins that bisect Africa from the Atlantic Ocean to the Indian Ocean. The combined length of these basins exceeds 7,000 km, with sedimentary thicknesses range from 14 km in the Termit Trough, eastern Niger, up to 7.5 km for the southern Chad basins (Doba, Doseo and Salamat basins), to in excess of 13 km for the Muglad basin, Sudan. Since these rift basins represent a zone of lithospheric weakness within the African plate, changes in the plate stress and movement have resulted in deformation being focused within this zone. Thus plate tectonic processes affecting the African plate have been recorded by the stratigraphy within the basins. The rift basins reveal a poly-phase development with synchronous stratigraphic events being recorded in each of the basins. At this time, only the major deformational events, can be correlated with changes in plate movement within the oceanic domain due to the limited resolution that the oceanic crustal fabric has in recording such events.
The presentation addresses both the mega tectonic setting of this rift system as well as focusing on the basin architecture of the southern Chad basins of Central African. For decades, these basins have been known to contain oil and it is only with the construction of the 1,070 km Chad-Cameroon oil pipeline from Kome (Doba basin) through Belabo to Kribi on the Atlantic coast of Cameroon, that oil companies are now able to develop this hydrocarbon province. The excellent regional coverage of gravity and aeromagnetic data has allowed the spatial extent, geometry and depth of these basins to be mapped. Well and seismic data have been used to control the model inversion.
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