The giant quartz vein of Catinga Hills (Datas/Gouveia, MG)

Abstract

The present paper describes a giant quartz vein that occurs along the Catinga hills, that integrates the Southern Espinhaço Range. This large quartz-vein is 1.7 km long and 30 m of maximum width, and it was exploited for siderurgy during the last two decades. Two main groups of veins comprise the probable ways of percolation and precipitation of silica. The most important group is concordant with the foliation of the host rock, showing north-south strike with medium to high dip values, while the other group is coaxial but discordant with the first one, and shows higher dip values to west. The giant vein shows a typical zoning that is characterized by increasing density of the veins from the host rock towards the core of the body. Such host rocks are metasediments of the Espinhaço Supergroup (Sopa-Brumadinho Formation) in the contact zone with gneisses and schists of the Archean basement. The origin of the fluids is related to hydrothermal solutions formed during the Brasiliano orogenic cycle (~625-540 My), in a late- to post-tectonic time. Keywords: Quartz, veins, deformation, Espinhaço Range.