Discovery and Geology of Low-Sulfidation Epithermal Gold Deposits in the East African Rift, Ethiopia, and Djibouti

Bimodal rift environments such as the northern Nevada rift can host low-sulfidation epithermal gold mineralization. In the search for new mineralized districts with bonanza gold potential, Stratex International Plc. applied this concept to the East African rift in 2008 and identified the Afar depression of Ethiopia and Djibouti as having potential. Several prospects were identified through satellite imagery analysis and field prospecting including the use of a helicopter to quickly assess more remote targets. Two prospects were drilled in Ethiopia and were considered a technical success with broad, low-grade gold intersections. In Djibouti, the discovery of the outcropping Pandora vein, which is up to 22 m wide and 1,500 m in strike, resulted in high-grade intersections including some bonanza grades. In addition to the Pandora vein system two other significant prospects have been drilled in Djibouti with Australasian Joint Ore Reserves Committee-compliant inferred resources defined by the African Minerals Exploration and Development Fund III. Mineralization is <1 Ma and possibly <100 ka hosted in the Stratoid Series basalts (4–1 Ma) and rhyolite dome complexes along graben margin faults. Mineralization occurred when the extensional faults disrupted lake-filled grabens coeval with felsic magmatism.