Petrology and radioactivity of the famous Aswan monumental red granites new occurrence, Gebel Um Shaghir area, South Western Desert, Egypt

Abstract

The basement rocks of Gebel Um Shaghir area are represented by amphibolites, gneissose granites, and small outcrop of coarse-grained younger red granites. The studied younger red granites have similar characteristics to the famous Aswan monumental red granites, such as morphology, color, mineralogical composition, and crystal size. Petrographically, Um Shaghir granites are coarse- to very coarse-grained and have subhedral granular texture. They are mainly composed of perthitic microcline, microcline, plagioclase, quartz, biotite, and arfvedsonite. Sericite, chlorite, and epidote are secondary minerals, while zircon, titanite, allanite, apatite, garnet, and opaques are accessories. Petrochemically, Um Shaghir red granites are alkaline A-type granites, generated in an extensional within-plate (WPG) environment. The probable origin of these granites is mainly fractional crystallization of calc-alkaline magma. Um Shaghir red granites could be recognized as uraniferous granites, where uranium mobilization post-magmatically could be indicated due to the wide range of eU contents (less than 2 to 21 ppm).