Mineralogy and Geochemistry of a New Uranium Occurrence at the Decant of Wadi El Reddah, Northeastern Desert, Egypt

Abstract

Gattar granites are affected by widespread deuteric and post magmatic hydrothermal activities. Hydrothermal alterations associated U-mineralization in the host granites include hematitization, sericitization, episyenitization (desilicification) and fluoritization. Alkali metasomatism is represented by microclinization, sericitization and muscovitization of alkali feldspar and plagioclase. Two new radioactive occurrences were discovered namely GXXIII and GXXIV. The first radioactive occurrences is located 150-180 m from the contact between the Gattarian granite and the Hammamat molasse sediments. The intersection show highly hematitized hallows with deep brown to reddish pink color associating some remarkable silicification. The other radioactive location is controlled by several factors mainly represented by the NE-SW basic dyke of 2-3 m thickness and bound the radioactive spots from the north. This radioactive location is located some 350 m from the GXXIV location and is more than 0.5 Km away from the granite-Hammamat contact zone. The location includes three radioactive spots arranged along major shear zone trending N25E-S25W.Generally, loss and gain calculations indicate that the altered samples exhibit an increase in total iron,

Notable changes in geochemical and mineralogical characteristics of different phases of episyenitization: insights on the radioactive and shielding of the late phase

“…Divergence from the range was uncommon and usually brought on by significant fractionation of auxiliary minerals or metasomatism. According to (Irber, 1999;Khamis et al, 2020), the majority of the highly desilicified episyenite samples show decreased Zr/Hf ratios and move towards smaller values (20). This indicates that these rocks were affected by severe magmatic-hydrothermal alteration in highly fractionated silicate melt.…”