Petrology, geochemistry and structural development of the Bir Safsaf-Aswan uplift, Southern Egypt

Abstract

The Bir Safsaf-Aswan uplift is an east-west striking major basement high in SW Egypt. It consists mainly of granitic gneisses intercalated with amphibolites, marbles and calc-silicates. It is intruded by syntectonic S-type granites and late-tectonic I-type granitoids and by alkaline basaltic plugs and different dyke generations. Data on the metamorphic evolution revealed an early high-T (∼800°C) event, followed by amphibolite-migmatite facies and then by greenschist facies conditions. The following preliminary geological evolution is proposed: the East African craton in SW Egypt was formed and metamorphosed under high T conditions in Pre-Pan-African times. The accretion of the Arabian-Nubian shield led to the ckening of the adjacent continental African crust which caused migmatization and formation of S-type granites. Late tectonic uplift resulted in a low-grade metamorphic overprint and in the formation of I-type granites at around 570 Ma. The end of the Pan-African development is documented by the intrusion of igneous dykes at 521 Ma. The Pan-African generated fracture system was frequently reactivated in the Phanerozoic, as indicated by the ages of fracture bound continental volcanic rocks (193 ± 5 Ma; 155 ± 4 Ma; 87−81 Ma).