Fluid inclusions in Adirondack granulites: Implications for the retrograde P-T path
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Investigation of fluid inclusions in granitic and cale-silicate gneisses from the Adirondack Mountains, New York, has revealed the presence of various types, including: (1) CO2-rich, (2) mixed H2O−CO2±salt and (3) aqueous inclusions with no visible CO2. Many, if not all, of these inclusions were trapped or modified after the peak of granulite facies metamorphism, as shown by textural relations or by the lack of agreement between the composition of the fluids found in some inclusions and the composition of the peak-metamorphic fluid as estimated from mineral equilibria. Many fluid inclusions record conditions attained during retrograde cooling and uplift, with minimum pressures and temperatures of 2 to 3 kbar and 200 to 300°C. The temperatures and pressures derived from the investigation of these inclusions constrain the retrograde P-T path, and the results indicate that a period of cooling with little or no decompression.
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