The Asosa region of western Ethiopia: a golden exploration opportunity

Abstract

Gold mining has a legendary history in Ethiopia, with Ethiopian mines providing gold to the ancient Egyptian empire and possibly even King Solomon's Mines and the Queen of Sheba. Today, gold occurs in the PanAfrican age schist belt and Tertiary basaltic lavas of the Asosa region of Benishangul-Gumuz, western Ethiopia. There is widespread artisanal gold production in the Asosa region, with moderate activity by small numbers of local workers producing relatively large amounts of gold. There is a strong relationship between predominantly shear zone-hosted gold deposits and the Kuluck shear zone, suggesting a structural control on gold accumulation. Gold is also commonly associated with secondary sulphide mineralization and magnetite alteration in Asosa rocks. The source of the gold is thought to be the sub-volcanic intrusions generated during the subduction of the oceanic crust at the trench island-arc system, akin to what we see today in epithermal and porphyry type gold systems. Historical workings and anomalous gold concentrations in rock, soil and stream sediments point to a potentially significant untapped gold resource in the Asosa region of western Ethiopia.

Petrogenesis of the Neoproterozoic rocks of Megele area, Asosa, Western Ethiopia

“…The Neoproterozoic rocks and associated intrusive of Megele area comprise granite gneiss, granodiorite, metabasalt, diorites, and genetically linked quartz-graphite schists (Amena et al, 2016;Bullock and Morgan, 2015;Bullock and Morgan, 2018). Granodiorite and granite gneiss intrusions were cut by different generations of the mafic dolerite dykes.…”

“…The Asosa area in the Western Ethiopian Shield which is the focus of this study has been one of the targeted areas for placer gold mining by artisanal workers since the 1930s (Bullock and Morgan, 2018). Based on the results of the field investigation, geological mapping and preliminary geochemical information (Bullock and Morgan, 2018) revealed that there has primary gold mineralization in shear zone related quartz veins, quartz-graphite schist, pegmatite, and quaternary basalts.…”

“…Furthermore, detailed studies have been conducted in specific parts of the area focusing on geotectonic evolutions (Ayalew and Johnson 2002), petrology, geochemistry, and tectonic settings (Kebede et al, 1999;Alemu and Abebe, 2007;Warkisa et al, 2021). The Asosa area in the Western Ethiopian Shield which is the focus of this study has been one of the targeted areas for placer gold mining by artisanal workers since the 1930s (Bullock and Morgan, 2018). Based on the results of the field investigation, geological mapping and preliminary geochemical information (Bullock and Morgan, 2018) revealed that there has primary gold mineralization in shear zone related quartz veins, quartz-graphite schist, pegmatite, and quaternary basalts.…”

“…Furthermore, (Bullock and Morgan, 2018) reported that there is an association of gold with pyrite, chalcopyrite, galena, and with minor pyrrhotite, hematite, and graphite ores. However, the petrological, geochemical, and tectonic setting description of the Neoproterozoic rocks of the Megele area is yet unknown.…”