Vein-type graphite deposits in Sri Lanka: The ultimate fate of granulite fluids

摘要: Hydrothermal graphite vein deposits hosted in granulite facies metamorphic rocks Sri Lanka are unique because of their large size and high crystallinity. In this paper, we present a review the structural-metamorphic setting veins stable carbon isotope data, fluid inclusion data from quartz host several Lanka. The studied show decompression rims plagioclase orthopyroxene after garnet. these rim textures comprise, order abundance, high-salinity brine, H2O-CO2, low-salinity aqueous inclusions. brine is responsible for metasomatic features observed garnet rims, including feldspar leaching re-precipitation. Quartz cogenetic with comprises, aqueous, CO2, H2O-CO2 Published indicates dominant mantle source, mixed small amounts carbon-bearing fluids supracrustal origin. We propose that quantities mantle-derived CO2 temporarily stored lower crust during final stage Gondwana supercontinent amalgamation. subsequently released crustal associated fast uplift. were formed uplift represent as such paleofluid channels. respect, they comparable to quartz‑carbonates mega-shear zones found other terranes. Depending on redox conditions, brines may either result formation or quartz‑carbonate veins.