Earth and Planetary Sciences ETDs

Publication Date

Spring 5-16-2026

Abstract

New mapping of the Grand Canyon’s Middle Granite Gorge (MGG) provides novel insights regarding the Paleoproterozoic tectonic development of southwestern Laurentia. Our data suggest that the 1.84 Ga Elves Chasm Gneiss, the oldest known rock unit in southwest Laurentia, underthrust the 1.75 Ga Granite Gorge Metamorphic Suite during ~1.73 Ga lithospheric assembly. The distinctive mineralogy of the contact zone allows it to be mapped across discontinuous exposures that define a regional NE-plunging F2 fold. Multidisciplinary datasets support a shear zone interpretation for the contact zone in preference to the previously proposed regolith interpretation. Monazite petrochronology and metamorphic studies indicate that D1 thrusting took place ~1.73 Ga at 720 °C, and 7 kbars; D2 folding took place during the ~1.70 Yavapai orogeny. We interpret D1 as an accretionary event in a forearc accretionary prism and the Elves Chasm tectonic block as an allochthonous microplate that was accreted during assembly of lithosphere.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Karl E. Karlstrom

Second Committee Member

Adrian Brearley

Third Committee Member

Marisa Repasch

Fourth Committee Member

Michael Williams

Keywords

Grand Canyon, Paleoproterozoic, Granite Gorge, Elves Chasm, metamorphism, Vishnu

Document Type

Thesis

Additional Files
Middle Granite Gorge Map 20251212.pdf (62278 kB)
1:24,000 geologic map of the Middle Granite Gorge
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Available for download on Tuesday, May 16, 2028

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