A New Uranium Occurrence, Gabal El-Missikat Prospect, Central Eastern Desert, Egypt

Abstract

Gabal El-Missikat post-tectonic granites represent one of the most promising examples of the fracture-filling uranium occurrences in the central Eastern Desert of Egypt. It includes several radioactive anomalies in which some are associated with U-minerals. These radioactive anomalies are controlled mainly by ENE-WSW trending shear fractures. In the present work, a new uranium occurrence (M-III) has been discovered in the north-western border of G. El-Misskat granitic mass. It is associated with jasperoid materials, occupying a NW-SE trending reactivated shear zone with tensile properties. The granites were subjected to intensive alteration, including silicification, sericitization, and kaolinization. In addition, a mixture of massive hydrated iron oxides (probably goethite and limonite) occurs as mammillae and botryoidally form in the centre of the shear zone. These hydrated iron oxides show colloform texture. They are resulted from the oxidation and hydration of magnetite and pyrite. Faults and their feathers, which are associated with the shear zone, structurally control the uranium mineralization at M-III occurrence. Visible secondary uranium minerals (mainly uranophane) are recorded as micro-fracture fillings. They are associated with deep violet-to black- fluorite in the highly brecciated and intensely ferruginated parts. The granites surrounding the shear zone are enriched in U and Th (mean 16 and 45 ppm, respectively).