Significance of carbonic fluids in the granulites and skarns of southeast Madagascar

In the granulites of southeast Madagascar, extensive skarns are the signatu re of intense fluid circulation coeval with regional metamorphism. Fluid in clusions in different minerals from gneisses and skarns are CO2-rich (X-CO2 greater than or equal to 0.8). Corresponding isochores are in good agreeme nt with mineral thermobarometry. Such fluids, with high P-CO2 and P-O2 and low P-H2O, are in equilibrium with the observed mineral assemblages. Contra ry to some assumptions that granulite facies were produced through fluid-ab sent metamorphism, these results demonstrate equilibrium between granulite mineral paragenesis and a CO2-rich fluid phase. ((C) Academie des sciences / Elsevier, Paris.).