P.I. Todd A. Ehlers - University of Michigan EAR-0309779
In the last 12 years a global scientific debate has ensued over if climate change or tectonics provided the impetus for the appearance, or reality of accelerated mountain uplift. This three year project at the University of Michigan will test the hypothesis that cooler climates, and more specifically glaciation, increase the topographic relief and maximum height of mountain ranges, thereby producing the appearance of accelerated uplift in the last ~10 Million years. Previous attempts to test this hypothesis have been hampered by a lack in understanding of the distribution and amount of glacial erosion over million-year time scales. This study will integrate geochemical data (low-temperature thermochronometers) with three-dimensional computer models to quantify the glacial erosion history in the southern Coast Mountains, B.C. The integration of new data collection and modeling for this study will involve several steps. (1) Two seasons of fieldwork will provide 60 new samples within a ~25x25 km area of the southern Coast Mountains. (2) Two years of computer program development are needed to modify an existing three-dimensional computer model to simulate evolving topography. The model will predict exposed sample ages under a variety of tectonic, and erosional scenarios. (3) The last two years will apply an inverse computer-modeling program to determine the range of glacial erosion histories, and ancient preglacial topographies, that satisfy the measured geochemical sample ages. The results from these three steps will test the stated hypothesis by reconstructing the mountain topography prior to glaciation in the Coast Mountains and assess if glaciation increased topographic relief. In addition to addressing a long-standing problem in the scientific community, this study will also provide a Ph.D. for one graduate student. The principle investigator and graduate student will give regular talks in K-12 school science classes on 'glaciers and ice ages' and at least one undergraduate student will be involved, and mentored in the research process.
