Geochemical Characterizations and Spectrometric Prospecting of the Arabian-Nubian Shield: A Сase Study from Abu Rusheid Area, South Eastern Desert of Egypt

Abu Rusheid area is a part of the Arabo-Nubian basement exposures and is located in the southern Eastern Desert of Egypt, 95 km southwest of Marsa Alam City on the Red Sea coast. The Precambrian basement rocks include (a) ophiolitic metagabbros, (b) ophiolitic mélange, (c) mylonitic rocks, and (d) granites which were later intruded by lamprophyre dikes, pegmatite, and quartz veins. Geochemical studies revealed that both the mica schist and mylonite are mainly arkoses to greywacke in composition and confined to the passive margin tectonic setting. Chondrite-normalized REE patterns illustrate enrichment in HREEs in mica schist relative to LREEs, and there is a balance between them in mylonite. The minerals that have been identified in both mica schist and mylonite are soddyite, uranophane, kasolite, metazeunerite, thorite, uranothorite, and zinnwaldite. These mineralizations are related to shear zones and mainly coincide with the Najd fault (left lateral strike-slip) shear system. Field spectrometric measurements revealed that the average eU is 219 ppm and eTh is 451 ppm along trenches, whereas along channel samples the average eU is 64 ppm and eTh is 271 ppm.