Setting of gold mineralization in the northern Red Sea Hills of Sudan

More than 40 ancient Au mines are noted in NE Sudan. Many of these mines were worked in Pharaonic times, and later activity has been almost entirely a re-exploitation of these ancient discoveries. Field relations newly noted at a number of the auriferous quartz veins are important for further prospecting in the Red Sea hills. Native Au occurs in quartz veins along with minor pyrite, chalcopyrite and arsenopyrite. The veins are pods and lenses with thin envelopes of sericitized rock. The country rocks are propylitized, sheared, in part mylonitic granodiorites, previously confused with greenschist facies metavolcanic rocks, which are intruded by the syntectonic Proterozoic calc-alkaline batholiths that contain the veins. The veins are localized by the shear zones, but are commonly disrupted by the latest shearing movements. Post-tectonic calc-alkaline intrusions and anorogenic alkaline complexes both cut across the shear zones. Mineralization is postulated to be the result of leaching of granodiorite and redeposition within a hydrothermal system circulating through the shear zones.