Metamorphic experiments on solid—solid reactions
Many metamorphic rocks crystallize or recrystallize under conditions which generate an essentially volatile-free mineral assemblage. As examples, one might consider rocks of the granulite facies which typically produce orthopyroxene—clinopyroxene—plagioclase ± garnet ± quartz assemblages in mafic compositions and quartz—plagioclase—alkali feldspar—sillimanite —garnet ± cordierite assemblages in pelitic compositions. Of even wider distribution than granulites are the recrystallized rocks of the upper mantle which are found as xenoliths in mantle-derived volcanics. Peridotites and eclogites are the commonest of such volatile-free xenoliths.
KeywordsExcess Free Energy Calorimetric Data Excess Enthalpy Phase Equilibrium Data Lead Silicate
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