Master of Science (MS)
First Committee Member
Terry L. Spell
Number of Pages
Thermochronologic data and geobarometry from the Granite Mountains indicate exhumation of mid-crustal plutons during Late Cretaceous extensional tectonics. U/Pb zircon and 40Ar/39Ar ornblende ages indicate intrusion, crystallization, and geologically instantaneous cooling through 500Ã‚Â°C at ∼75 Ma. K-feldspar multi-diffusion domain modeling indicates a cooling rate gradient from SW to NE of 63, 32, and 16Ã‚Â°C/Ma for three samples spanning a transect across the range. NE K-feldspar cooled through ∼252Ã‚Â°C by 73 Ma while other samples remained >375Ã‚Â°C suggesting a short lived down-to-the-east normal faulting event at ∼75 to 74 Ma. Faster cooling rates with later initial K-feldspar recording (∼71 Ma) suggest extension continued along a shallow down-to-the-southwest detachment active from ∼73 to 69 Ma. U-Th/He apatite ages suggest the Late Cretaceous extensional event juxtaposed the deeper-seated Granite Mountains plutons with the shallow-level southern Providence Mountains plutons and the two cooled through 70Ã‚Â°C as a single block.
California; Collapse; Complex; Exhumation; Geobarometry; Granite; Mountains; Orogen; Plutonic; Sevier; Southeast; Thermochronology
University of Nevada, Las Vegas
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Kula, Joseph Louis, "Thermochronology and geobarometry of the Granite Mountains, southeast California: Exhumation of a plutonic complex during collapse of the Sevier orogen" (2002). UNLV Retrospective Theses & Dissertations. 1434.