Ca- and Fe-rich metasomatic CO₂ fluids in granulite-facies felsic gneisses from Madagascar and its influence on elastic velocities

Abstract

Felsic gneisses were affected by at least two fluid-rock interaction events during granulite-facies metamorphism. The charnockitization-related fluid event and an additional Ca-Fe metasomatic event could be identified in metasomatized felsic gmeisses in Madagascar. At this locality, the metasomatised part display a distinct change in mineral assemblage. The results were achieved by petrographic analysis and point counting in selected thin sections. The results suggests that Ca-Fe metasomatism was occured late during the fluid infiltration history.