Education B.S. Geology, 2006 California State University, Fullerton B.S. Computer Science, 2006 California State University, Fullerton Current Research Tertiary erosion and incision history of the north-central Colorado Plateau The mechanism, timing, and amount of uplift and erosion of the Colorado Plateau are poorly constrained and several hypotheses have been proposed, including flat-slab subduction, crustal thickening, and mantle anomalies such as early Cenozoic Laramide uplift and late Cenozoic epeirgeny, each having distinct temporal and spatial characteristics. We hope to determine the exhumation history of the plateau by combining apatite (U-Th)/He thermochronology with numerical modeling. Uplift can increase the rate of stream incision, scarp retreatment, and erosion, all of which will produce distinct cooling signatures in surrounding rocks. Low temperature thermochronology will establish the thermal history of Colorado River incision and escarpment retreat in the Book Cliffs area of Utah, constraining both the timing and magnitude of exhumation of the Colorado Plateau. Combined with flexural isostatic models, net tectonic-rock uplift can be calculated for each tectonic model to determine the evolution of the current surface elevation and landscape. Past Research The Talkeetna Mountains, located just north of Anchorage, are in a key location to study the effects of Cenozoic shallow subduction of the Yakutat microplate in southern Alaska. To address the rate and timing of exhumation of this area, apatite (U-Th)/He thermochronology was used to determine the ages of granite and granodiorite samples. The early Miocene (U-Th)/He ages indicate that the most recent exhumation event of the southern Talkeetna Mountains may be associated with the early stages of Yakutat microplate subduction 15-20 Ma. Teaching Fall 2004, Teaching Assistant, Geologic Field Techniques, CSU Fullerton Publications Hoffman, M. D., 2006, Miocene Exhumation of the southern Talkeetna Mountains, south central Alaska, based on apatite (U-Th)/He thermochronology, Dimensions: Journal of Undergraduate Research in Natural Sciences and Mathematics, California State University, Fullerton, v. 8, p. 63-68. Hoffman, M. D. and Armstrong, P. A., 2006, Miocene Exhumation of the southern Talkeetna Mountains, south central Alaska, based on apatite (U-Th)/He thermochronology, Abstracts with Programs, Geological Society of America Cordilleran Section Meeting, v. 38, no. 5, p. 9. Last updated 31 October 2006. |
