Scale of pluton/wall rock interaction near May Lake, Yosemite National Park, California, USA Public Deposited

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  • March 22, 2019
  • Mills, Ryan Douglas
    • Affiliation: College of Arts and Sciences, Department of Geological Sciences
  • The western outer granodiorite of the Tuolumne Intrusive Suite intruded a variety of metasedimentary wall rocks at 93.1 ± 0.1 Ma. The May Lake metamorphic screen (4500 x 550 m) is a remnant of the chemically diverse metasedimentary host rocks. Their chemical contrast with the invading pluton provides an excellent location to study pluton/wall rock interactions. Outside the screen, visible wall-rock xenoliths (mostly pelitic quartzite) are predominantly located in an elongate horizon surrounded by a hybridized fine-grained granodiorite. Initial Sr and Nd isotopic ratios of the hybridized granodiorite indicate incorporation of crustal material. Major- and trace-element geochemical data indicate contamination of the granodiorite with pelitic metasedimentary rocks occurred in two modes, selective assimilation of 1) a high-K partial-melt derived from pelitic quartzite, and 2) a low-K partial-melt derived from pelitic quartzite. However, there is little evidence for contamination of granodiorite beyond the immediate vicinity of wall rock inclusions.
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  • Glazner, Allen F.
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  • University of North Carolina at Chapel Hill
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