Geological studies of the Umm UD gold prospect, Eastern Desert, Egypt / Youssry Mohamed Mohamed Esmail ; Supervised Mohamed A. Elsharkawi

Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Geology

The present study considers the basement rock units and the mineralized zones incorporated in one o f the old gold mine (Umm Ud) in the Eastern Desert o f Egypt. The study area lies between latitudes 24{u00B0}48'00" and 24{u00B0}50'00" N and longitudes 34{u00B0}40'30" and 34{u00B0}44'30". This study aims at investigating the rock units and mineralized veins in the study area in terms o f petrography, opaque mineralogy, geochemistry, gold content as well as discussing the possible origin o f the mineralization. The study revealed that the main rock units encountered are the ophiolitic serpentinites and related rocks, the island arc metavolcanics and metavolcaniclastic rocks and the subduction-related (G1) granitoid rocks (diorite/ quartz diorite). Geochemical investigation indicated that the studied serpentinites are mainly o f parent lherzolite composition and similar in many aspects to the ophiolitic serpentinites found in many areas in the Eastern Desert o f Egypt. The studied metabasalts and metatuffs are calc-alkaline to tholeiitic. They belong to the island arc assemblage as indicated by the tectonic setting diagrams used in the study. The intrusive dioritic rocks show a calc-alkaline affinity and plot in the volcanic arc-syn-collision granite field. The mineralized quartz veins show relatively high content o f Cr and Ni (up to 186 ppm and 115 ppm respectively) and contain gold (up to 11.65 ppm). which is either found as inclusions in sulfides (mainly pyrite) or as a very minute free native crystals as indicated by the SEM and EDX analyses. The possible genesis o f gold in the study area can be explained by the effect o f the dioritic intrusion as a heat engine that led to the mobilization and leaching o f gold (and other elements) from the surrounding ophiolitic and island arc rocks and their deposition in the hydrothermal quartz veins and alteration zones connected with the dioritic intrusion

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