Abstract

K, Na, and CO 2 were progressively lost during the metamorphic event. No mass transfer of Fe, Mg, Ti, Si, or Ca. Sodium was probably lost through a mineral-fluid hydrolysis reaction that destroyed the albite component of plagioclase and produced quartz, anorthite, and a soluble Na-bearing fluid species. Potassium was probably lost independently through a mineral-fluid hydrolysis reaction that destroyed biotite and formed calcic amphibole, sphene, anorthite, and a soluble K-bearing fluid species. H 2 O was also progressively lost. Observed amount of mass transport of K and Na requires 1-10 rock volumes of fluid interacting with the carbonate rocks. Regional metamorphism considered as possible large-scale acid metasomatism.--Modified journal abstract.

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