Epithermal gold occurrences in the lakes district of the Main Ethiopian Rift and Tendaho area of the Afar Rift: discovery of a metallogenic province

Plio-Quaternary volcanic products cover a large part of the Main Ethiopian Rift (MER). Epithermal gold occurrences related to Quaternary volcanics are at present being closely studied for their precious metal potential. Low sulphidation (Adularia-sericite-type) occurrences have been found. Analyses of 579 core and cutting samples collected for the purpose of exploratory geothermal studies from a number of localities (Gedemsa, Aluto and Corbetti calderas MER, and the Tendaho graben; Afar) were analyzed for gold. The results showed concentration of gold ranging from 100 ppb to 440 ppb. Values ranging between 200 and 300 ppb are very common. The overall characteristics of the known ore occurrences and the evolution of the Quaternary central volcanoes within the MER, and related epithermal processes seem to delineate an individual, homogeneous metallogenic province. A new field of investigation on epithermal ore occurrences which are unusual for the present Ethiopian metallogenic scenery is probably emerging. A study of these phenomena, in light of recent acquisitions in metallogenic knowledge, could be of interest not only for further scientific studies but also for new possibilities in mining activity. This study presents the occurrences of epithermal gold mineralization in the MER, the only one of its kind so far reported in the East African Rift System. SINET: Ethiopian Journal of Science Vol. 24, No. 1 (June 2001), pp. 69-91 Key words/phrases: Caldera, epithermal gold, metallogeny, Plio-Quaternary, rift volcanic