Melut Basin Tectonic Evolution and Comparison of the Sudanese Rifts with the West and Central African Rift Systems (WACRS)

Mohamed, Imam A. M., Petrodar Operating Cmpany, Khartoum, Sudan

Melut basin is an extensional to transtensional basin oriented NW–E and terminated against the Central African Shear Zone. The basin dimension is 260X96 km and filled with 8000 m. of none marine clastic sediments of Jurassic (?)-Tertiary ages. The depositional sequence is lacustrine shales with fluvial-flluvial sandstones and conglomerate. Seismic, gravity and magnetic indicates three fault trends N–S, NW-E and SW–NE which change to E-W. Principle extension in Melut basin is E–W then shifted to NW–SE during late Cretaceous and early Tertiary. The dominant features in south Melut are two half grabens trending N–S, dips to east and full grabens oriented NW–SE in north Melut. The major oil discoveries are associated with SW–NNE faults. Two rifts system is recognized, the last rift ends in Miocene. From Miocene to Quaternary the basin is calm with several volcanic activ­ities in South Melut.

Exception from other basins, Khartoum is a sag basin oriented N–S and the Blue Nile half grabens are dipping to the west. The Blue Nile basin is most likely related to the sepa­ration of Madagascar and India from Africa and probable for Melut basin. Other rift stages in the Blue Nile basin are similar to WACRS. Recent seismic data in South Atbra basin indi­cates strong compressional features, which is related to CAZS.

Both the Sudanese and WACRS have the same crude characteristics, similar structural styles and showing Cretaceous similarity but with differences in Tertiary, which may suggest the Sudanese rift is affected by the rapid moving of India, Red Sea opening