Title: Professor
Degree: Ph.D., University of Southern California
Specialty: Metamorphic Petrology, Tectonics
Research Interests: I pursue studies in the area of Metamorphic Petrology with the goal of inferring the tectonic processes associated with burial and exhumation. I have conducted research throughout the western US, focusing on problems related to Cordilleran orogenesis. I integrate several approaches, thermodynamic modeling of mineral chemistries to establish pressure-temperature (P-T) paths, 2-d numerical thermal modeling of thrusts and detachments, thermochronology, and field relationships. I utilize thermobarometry to determine the peak conditions of metamorphism, and Gibbs method calculations involving Duhem's theorem to determine pressure-temperature paths from growth-zoned garnets. In order to place P-T paths into a quantifiable tectonic context, I have written computer codes to simulate the thermal effect of thrusting and exhumation using planar and listric fault geometries. Various geochronologic techniques are employed to determine the timing of garnet growth and the cooling of an area. Cooling histories are determined mainly by Ar-Ar thermochronology. Recently, tiny monazite inclusions in garnets from upper-amphibolite facies rocks from the Grouse Creek Mountains were dated using the high resolution ion microprobe facility at UCLA, and were interpreted as occlusion ages, and therefore record the ages of garnet growth. The geochronologic data combine with the P-T path data to provide the constraints necessary to prepare numerical simulations of thermal history and infer both rate the rate of slip and dip along faults that buried the rocks, leading to their metamorphism, and their subsequent exhumation.
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Office: 227 Frier Hall (Building 12)
Phone: 928-523-1904
e-mail: Thomas.Hoisch@nau.edu
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Department of Geology
P. O. Box 4099
Frier Hall, Knoles Drive
Northern Arizona University
Flagstaff, AZ 86011-4099