Award Date
1-1-2000
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Geoscience
First Committee Member
Michael L. Wells
Number of Pages
154
Abstract
New studies of the Pinto shear zone, New York Mountains, California, improve our understanding of the importance of Mesozoic extension in Mojave Desert and also contribute to the growing body of evidence for syncontractional extension in the Mesozoic Sevier orogen. The Pinto shear zone has a Z-shaped map pattern and foliation in the ∼92--97 Ma Mid Hills adamellite of the Pinto shear zone generally dips 20--65° S and SW. Sense of shear indicators demonstrate top-to-the S-SW shearing, parallel to a S-SW plunging lineation, suggesting the Pinto shear zone is a normal fault. Hanging-wall deformation is accommodated by antithetic high-angle faulting localized along porphyry dike margins. Deformation fabric within the shear zone grades structurally upwards from undeformed footwall granitoids beneath the shear zone to protomylonite, mylonite, and ultramylonite near its top. Microstructural studies of mylonite and ultramylonite indicate that deformation occurred over a broad range of decreasing temperatures, from lower amphibolite-uppermost greenschist through lower greenschist facies conditions. The decrease in temperature of deformation probably occurred during progressive deformation. (Abstract shortened by UMI.).
Keywords
California; Desert; Kinematics; Mojave; Mountains Northeastern; Pinto; Shear; Timing; York; Zone
Controlled Subject
Geology
File Format
File Size
5632 KB
Degree Grantor
University of Nevada, Las Vegas
Language
English
Permissions
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Repository Citation
Beyene, Mengesha Assefa, "Kinematics and timing of the Pinto shear zone, New York Mountains, northeastern Mojave Desert, California" (2000). UNLV Retrospective Theses & Dissertations. 1180.
http://dx.doi.org/10.25669/jpbp-0w9q
Rights
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