Redepositions and structural development of the Uweinat-Safsaf-Aswan uplift system

Abstract

Epeirogenic movements and fracture tectonics with the main directions NE-SW, E-W and NE-SW, have been essential factors controlling erosion and sedimentation processes in the area of the Uweinat-Safsaf-Aswan Uplift System since Precambrian time. The sediments of this area are mainly clastic and are mostly of fluvial origin. They are of Silurian to Upper Cretaceous age. Sedimentological and geochemical investigations from this area show different stages of maturity. The relatively high content of medium stable heavy minerals (Staurolithe, Disthene and Epidote) in samples of the Lakia Formation (Permo-Triassic — Lower Jurassic) indicates nearness to a metamorphic source rock area. In Paleozoic time the area between Gebel Uweinat in the West, Bir Safsaf in the East and the Lakia area (Northern Sudan) in the South was not influenced by the NW marine transgressions because of a NW-SE oriented uplift. The earliest marine sediments belong to the Gilf Kebir and Selima Formations of Late Jurassic — Early Cretaceous age. This material, probably redeposited several times due to E-W striking epeirogenic movements in the Jurassic, shows a heavy mineral association comprising mainly extreme stable minerals (Zircone, Tourmaline, Rutile). Because of subsidence in the area of southern Egypt — northern Sudan and the development of the Dakhla Basin a transgression in Aptian time reached the area of the southern part of the Misaha Trough and Selima. It can be stated that the northern and southern parts of the Misaha Trough were subjected to a different tectonic development. Before Aptian the southern parts must have been a highland related to the northern part hence N-, NW-transgressions could not reach the Gebel Abyad area. The subsidence of the southern Misaha Trough was closely connected with NE-SW striking fault systems which were also responsible for the development of geologic younger basins (Upper Nile Basin). The first marine influence in the Gebel Abyad area can be dated as of Senomanian.