Gravity study of the White Nile Rift, Sudan, and its regional tectonic setting

A compilation of 675 Bouguer gravity values for central Sudan show the presence of a series of linked gravity minima of approximately 40 km width and amplitude 200-300 g.u. to the east and north of the Nuba Mountains. These anomalies are interpreted as delineating the low-density sedimentary infill of the White Nile Rift. A broader 150 km wide positive Bouguer anomaly of amplitude less than 300 g.u. is centred over the Rift in the southern part of the study area and is interpreted in terms of a thinned crust beneath the Rift. Such a model is consistent with the subsidence nature of the Rift. The White Nile Rift is similar in tectonic character to the Southern Sudan Rift and the Blue Nile and Atbara fault controlled basins in that these Cretaceous/Tertiary structures all follow similar structural trends and terminate in line at their northwest end. This termination is considered to be caused by a structural lineament, possibly a shear zone, extending the Central African shear zone through Sudan. The form of the lineament is unknown but is considered to have had a major structural control on the development of deep sedimentary basins in Sudan since Cretaceous times and on the development of the Red Sea.