Petrogenesis and geological implications of the trachytic rocks in the South Eastern Desert, Egypt: mineralogical, geochemical, and radioactivity insights

Abstract

ABSTRACT The investigated Phanerozoic volcanic (Gabal Um Itly, G. El Beida, G. Um Domi and G. Um Doweila) areas in the south Eastern Desert of Egypt of the Northern Arabian-Nubian Shield (ANS), have been a peralkaline affinity and display a continuous composition trachyte rocks. Geochemically, the studied rocks show significant negative anomalies in Ba, Sr, and Ti on the primitive mantle normalized trace element plot, indicating an ancestry involving plagioclase and Fe-Ti oxide fractionation. The concentrations of uranium mineralization and rare earth elements in the trachyte rocks is related to the presence of uranophane, kasolite, umohoite, autunite, monazite and allanite. The distribution of uranium, thorium and their ratios in the trachyte rocks reflects a direct strong relation, which suggests that U distribution is, at least in part, governed primarily by magmatic processes and disturbed later by a hydrothermal solution.