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P-T Constraints Of Orthogneiss, Metapelites, And Ultra-Mafic Lenses Located In The Virgin Mountains Of Northwestern Arizona, Bryan R. Nielson, Brady M. Nielson, Andrew Schroeder, Mark R. Colberg

The Compass: Earth Science Journal of Sigma Gamma Epsilon

The Virgin Mountains, located in northwestern Arizona, host a variety of different geologic features. Many workers have focused on Tertiary extension within the mountain range, but little work has been done on the Paleo-Proterozoic basement rocks. Tertiary extension has exposed 1.73 – 1.80 Ga basement material that exhibits intense shear deformation and evidence of high temperature/high pressure and possibly ultra-high pressure metamorphism. These rocks are well exposed throughout Elbow and Lime Kiln Canyons, which are located east and south of Mesquite, Nevada. Some exposures enclose ultra-mafic lenses containing pyroxene/spinel pseudomorphs after garnet. These features suggest decompression through the garnet-spinel transition. …