Abstract

Gold mineralization in alluvial deposits of the Southern Espinhaço Mountains has been known since the 17^th century, but the recognition of primary gold mineralization in quartz veins embedded in supracrustal rocks dates back to the mid-19^th century and has been explored ever since. Morro do Ouro located in the central area of the Espinhaço Range is made up of hematitic phyllites from the basal unit of the Espinhaço Supergroup and on its frontal slope (west) it is delimited by an inverse fault that allowed the percolation of metasomatic fluids and the generation of gold-bearing quartz veins. The gold particles are embedded in the quartz of veins that cut through and, or are lodged in the schistosity of the hematitic phyllites. In the Serra do Espinhaço, dozens of gold deposits similar to those of Morro do Ouro are known, including the Mil Oitavas, Serra do Pasmar and Costa Sena mines. All this gold mineralization are epithermal deposits due to the low temperatures of the mineralizing fluids and their late insertion in relation to the orogenic structures, also characterizing them as lode deposits in the context of the regional orogenic gold deposits. The occurrence of similar gold mineralization in rocks of the Minas Supergroup (Paleoproterozoic) of the Iron Quadrangle indicates the regional character of the event and the mineralization processes. This late Neoproterozoic gold mineralization was the result of regional crustal heating caused by the subduction of the oceanic plate related to the tectonic inversion of the Brasiliano/Pan-African orogeny

Keywords:Gold; Morro do Ouro; Orogenic epithermal deposits; Espinhaço mountain range