Abstract

Laboratory and field studies were made on Precambrian igneous and metamorphic rocks in the southwestern Wind River Mountains. A granite stock and related pegmatite and quartz veins have been emplaced in pelitic and quartzo-feldspathic metasedimentary rocks, which are mostly quartz-plagioclase-hornblende and quartz-biotite-plagioclase porphyroblastic schists belonging to the almandine-amphibolite regional metamorphic facies. A contact aureole belonging to the hornblende-hornfels contact metamorphic facies surrounds the granite stock and the greenschist facies mineral assemblages were produced by recrystallization of these metamorphics and the granitic rocks during retrogressive metamorphism. At least three phases of metamorphic adjustment have occurred--almandine-amphibolite regional metamorphism, contact metamorphism, and a retrogressive period of metamorphism.

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