A METALLOGENIC EVOLUTION MODEL FOR THE LEAD-ZINC DEPOSITS OF THE MESO AND NEOPROTEROZOIC SEDIMENTARY BASINS OF THE SÃO FRANCISCO CRATON, BAHIA AND MINAS GERAIS, BRAZIL

Abstract

Integrated studies carried out on the Proterozoic sediment-hosted Pb-Zn sulfide deposits of the São Francisco Craton, Brazil, allowed the estimation of (1) ages of the host sequences, (2) timing of mineralization, (3) possible sources of metal and sulfur, (4) temperature and salinity range of mineralizing solutions, (5) sources of fluids and (6) possible mechanisms of fluid flow. Contrary to the deposits from other Proterozoic basins, the Brazilian deposits do not contain world class metal reserves. This can probably be attributed to the lack of sufficient investments in exploration and mining development research activities. However, the sulfide deposits of the São Francisco Craton do share several important geological, structural, isotopic and fluid characteristics with some of the giant deposit types. Using these data we develop a more realistic metallogenic model for the Proterozoic sediment-hosted Pb-Zn sulfide deposits.