Field Features, Mineral assemblages and Geochemistry of Radioactive Pegmatite in the Wadi Abu Zawal Area, North Eastern Desert, Egypt

Document Type : Original Article

Authors

Nuclear Materials Authority of Egypt

Abstract

Granitic pegmatites of the Wadi Abu Zawal area, North Eastern Desert of Egypt, intruded the syn-tectonic granites, younger gabbros and post-orogenic granites. Two unzoned pegmatite masses are quarried for feldspars and quartz, which injected within the older granites. One of them shows high radioactivity related to formation of U-Th-REEs mineralization. The mineralization occurs at the margins of this pegmatite body in close proximity to contacts with the host older granite. Hydrothermal hematite, kaolinite and epidote are dominant along the contact zone. Petrographic observations showed that the mineralized parts are mainly albite-rich with minor quartz and muscovite. The hydrothermal mineral assemblage contains secondary uranium minerals (uranophane and kasolite), uranothorite and monazite-Ce. The mineralization occurs as stains or crystallizes in the microsfractures of the pegmatite. Whole-rock analytical data of albite-rich samples display high contents of Na2O, CaO and Al2O3 with significant lower concentrations of SiO2 and K2O. The analyzed samples are enriched with U, Th, REEs, Zn, Pb, Sr and Ba. Detailed field, mineralogical and geochemical data have provided evidence that the investigated pegmatite has similar characters to other fractionated NYF-type pegmatites in the North Eastern Desert of Egypt.

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