Geology and Radioactivity of the Basement Rocks of Wadi El-Sahu Area, Southwestern Sinai, Egypt

The study area is covered by basement and sedimentary rocks. The basement rocks are represented by paragneiss, orthogneiss and younger granites, while the sedimentary succession is represented by clastic Paleozoic rocks. The younger granites are microscopically distinguished into monzogranite and syenogranite. Geochemically, the studied younger granites are peraluminous with alkaline affinity (moderately alkaline) originated in extensional regime. Monzogranite belongs to I-type granite formed in volcanic arc tectonic setting, while the syenogranite belongs to A-type formed in within-plate tectonic setting. The studied gneisses are nearly non-radioactive, whereas the studied younger granites are moderately radioactive where monzogranite is relatively higher than the syenogranite. The radio elements of these younger granites are incorporated in their accessory minerals such as zircon, xenotime and allanite. An anomalous quartz vein containing deep violet fluorite and kasolite is recorded cross-cutting the younger granites.