Uranium and rare metal mineralization in the El Sela and Qash Amir granitic intrusions, south Eastern Desert, Egypt

Abstract

The Gabal El Sela and Gabal Qash Amir younger granites in the Arabian Nubian Shield (ANS) occurred within the Onib- Sol Hamed suture zone in the southern Eastern Desert of Egypt. In the study area, a pluton composed of biotite granites, muscovite granites and two mica granites is crosscut by altered dibase, microgranitic and bostonite dykes with a distinctive distribution of mineralization with high concentrations of rare metals. Silicification, hematitization, kaolinitization, episyenitization and sericitization are the main hydrothermal alteration processes in these younger granites. Gabal El Sela fractured younger granite shows highly alteration, uranium enrichment and a strong enrichment in some rare elements (such as; Zr = 2287 ppm, Y = 1123 ppm and Nb = 269 ppm) whereas, the bostonite dyke (such as; Zr = 1604 ppm, Y = 709 ppm and Nb = 292 ppm). Gabal Qash Amir muscovite granite shows a favorable enrichment in some rare elements (such as; Zr = 1898 ppm, Y = 181 ppm and Nb = 966 ppm) while, the bostonite dyke (such as; Zr = 1500 ppm, Y = 711 ppm and Nb = 286 ppm).

Mineral characterization of the highly radioactive zones shows enrichment in autunite, uranophane, uranothorite, zircon, xenotime, monazite, fergusonite, samarskite and columbite. Field radiometric measurements of the studied El Sela fractured granite revealed that eU reaches up to 459.5 ppm, bostonite dyke eU reaches up to 58 ppm and altered basic dyke eU reaches up to 1625 ppm, while Qash Amir muscovite granite eU reaches up to 51 ppm and the bostonite dyke eU reaches up to 34 ppm.

Geological, mineralogical, radiometrical and geochemical studies indicated that Gabal El Sela fractured younger granite is the most promising area characterized by strong enrichment in both uranium and some rare metals mineralization than Gabal Qash Amir muscovite granite.