Petrogenesis And Geochronology Of The Granitic Intrusions Of Gabal Kulyiet And Seiga, South Eastern Desert, Egypt

Abstract

In the South Eastern Desert of Egypt tonalite. granodiorite and granite intruded intermediate to acidic metavolcanics and volcanogenic metasedimentary rocks of Precambrian age. The geological features of these granitic masses were investigated and a geological map (scale 1 : 40 000) was prepared. They have been classified into two groups: tonalite and granodiorite (syn to late-tectonic), and biotite and Muscovite granites (younger granitoids). The two groups appear to be genetically related on the basis of their major and trace element contents. The chemical compositions of these tonalitic to granitic rocks indicate that these granitic rocks belong to calc-alkaline series. The magma, during crystallisation, was under 3-4 kb pressure. Radiometric age determination indicates that they have a Pan-African age of 589 to 603 Ma. It is believed that these granitic intrusions have been intruded directly after the tectonic modification of an island arc.