Fluid Flow during Metamorphism and its Implications for Fluid—Rock Ratios

摘要: The study of metamorphic rocks is traditionally approached as an investigation mineralogical changes occurring responses to variations only in pressure and temperature. Despite the losses large volumes fluid during prograde metamorphism, are often regarded, on thin section scale, systems able buffer chemical potentials (µ) all components therefore essentially closed. There several important reasons, apart from its simplicity, for adherence this model. First, there observation that metasediments maintain their original sharp compositional discontinuities even amphibolite facies (e.g., Chinner, 1960). Second, low variance assemblages (implying internally buffered µ’s) common. Finally, metasomatic externally controlled activities generally lead simple mono- or bimineralic zones such those found skarns veins Tilley, 1951; Burnham, 1959; Thompson, 1959). Such occur between interbedded metapelites carbonates but not a observed phenomenon mixed pelitic/psammitic units.