Intrusion-related Low Sulphidation Gold Mineralization, Wadi Hammad Area, North Eastern Desert, Egypt

Abstract

: Gold mineralization in Wadi Hammad is one of few gold occurrences located in the North Eastern Desert of Egypt, occurring at the boundary between the post-tectonic Younger granite and Dokhan volcanics along a north-south (N-S) trending shear zone between them. The main mineral assemblages include arsenopyrite-pyrite-chalcopyrite-galena-sphalerite and sphalerite-gold-covellite-cerussite-pseudomorphic iron oxides. Mineralogical and geochemical studies indicate that the mineralization is of the low sulphidation epithermal gold type, with Pb-Cu type base-metal sulfides. The hydrothermal solutions forming the mineralization have temperatures between 200 and 300 °C. The mineralization formed in three main stages; the first one includes the intrusion of younger granite into the Dokhan volcanics coeval with the initial shearing along the contact between them and responsible for the formation of the main milky white quartz–polymetallic sulfide vein. The second stage is related to later (third and fourth) deformational events responsible for the formation of the grey-colored quartz hosting sphaleriteII-gold-covellite-cerussite-pseudomorphic iron oxides and connected with the basic dolerite dykes and related hydrothermal solutions. This stage includes the release of gold from their main sulfide hosts and re-precipitation in the fractures in quartz vein and alteration zones. The results of this study reveal the existence of promising gold deposits in the North Eastern Desert (NED) of Egypt, which changes the stereotype and may set the stage for future exploration of gold in the NED. Moreover, this study unveiled the nature of the intrusion-related type of mineralization and their characteristic features which can be used in the exploration of similar types in the surrounding areas.