Stable Isotope Investigations on the Granulite Facies Terrains of Brazil: A Review

Stable isotope data from three areas in the granulite facies terrains of Brazil are assembled and discussed. All the three areas (Jequié, Guaxupé and Sمo José do Rio Pardo) are from the Sمo Francisco Craton. The carbon isotope composition of the fluid inclusion CO2 in the Archean granulite terrain of Jequié indicate the participation of two distinct sources, an upper mantle source and an internal source of Archean organic matter. The isotope data may be interpreted in terms of the granulite genesis due to the intrusion of magma in the lower crust. The singularly uniform carbon isotope data for CO2 fluid inclusion of plutonic granulites is a clear indication of the magmatic addition of CO2-rich volatiles from deeper crustal sources. In the Sمo José do Rio Pardo area sulfur and carbon isotope data of scapolites from the granulites imply the derivation of volatiles from internal sources. The whole rock oxygen isotope data of the amphibolite and granulite facies gneisses from Guaxupé indicate a small scale variation of d18O values, compatible with the chemical data, suggesting the preservation of pre-metamorphic oxygen isotope composition. The isotope data of the granulites from Sمo Francisco Craton indicate non-pervasive fluid flow during metamorphism.