Early Proterozoic Evolution of the Alto Jauru Greenstone Belt,Southern Amazonian Craton,Brazil

The Alto Jauru Greenstone Belt in west-central Brazil comprises three belts of Early Proterozoic volcano-sedimentary sucessions that were invaded by Early to Middle Proterozoic intrusions, including tonalites, gabbros, and granites. Volcanic rocks represent a bimodal suite with ultrabasic-basic rocks of komatiitic-tholeiitic affinities at the base and intermediate-felsic calc-alkaline lavas and pyroclastic units on the top. Chemical differences exist between basic volcanic rocks from the Jauru Belt and those from the Cabacal Belt, but the volcanic rocks and the Cabacal Tonalite appear to be related to an island-arc environment and possibly were generated from the same mantle source. The volcanic-volcanoclastic sequence in the Jauru Belt hosts important deformed, gold-rich volcanogenic massive sulfide deposits.