Estudo da mineralização do Depósito Andradas, Caçapava do Sul - RS

Abstract

The evidence of copper mineralization in Cerro dos Andradas, located in Caçapava do Sul, belongs to the Província Cuprífera do Escudo Sul-rio-grandense. The host rocks are metavulcanic of mainly intermediate composition of the Passo Feio Metamorphic Complex. This work has as objective the definition of the main copper sulphides and the present alterations, thus determining the mineral paragenesis of the area. The methodology consisted of field activities to recognize the area and study of two drill holes, as well as a microscopic study of thin sections and mineral chemistry with the EDS (Energy Dispersive System) coupled to the scanning electron microscope. The order of events that affected the region of the Andradas Deposit was the following: carbonation, silification, chloritization, sulphide formation and subsequent supergenic alteration with formation of Fe-Cr-Ni oxides. The metallic paragenesis of the area is composed mainly of the sulfides of copper calcosite and bornite, mostly inside veins associated to carbonate and quartz. What is a feature of deposits formed through metamorphic processes, which tend only to form ore veins in open and fissural spaces in the rock.