HR: 1340h
AN: T23C-0580    [Abstracts]
TI: Connecting Topographic Analysis With Colorado River Incision History: Sensitive Gauges of Neotectonics in the Rocky Mountains
AU: * Sandoval, M
EM: msandova@unm.edu
AF: Univeristy of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, NM 87131
AU: Coblentz, D
EM: coblentz@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545
AU: Karlstrom, K
EM: kek1@unm.edu
AF: Univeristy of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, NM 87131
AU: Sussman, A
EM: spring@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545
AB: The topography of the Earth's surface provides important information for regional and global geomorphic studies because it reflects the interplay between tectonic-associated processes of uplift and climate-associated processes of erosion. The tectonic provinces of the Western U.S. are readily identifiable based on numerous geologic and geophysical investigations - however, it has proved difficult to arrive at measures of the differences between landscapes and to deduce quantitative information about the underlying tectonics using the traditional qualitative approach to evaluating topographic fabrics. By combining a rigorous quantitative topographic analysis approach with an analysis of the Colorado River drainage, we seek to improve our understanding of the relationship between present topography and active tectonics, as well as the time dimension for effects of tectonics on landscape evolution. The Colorado River drainage provides a unique natural laboratory to evaluate to relationship between lithospheric-scale tectonic processes and the observed physiography. The drainage, extending more than 1400 km from the Gulf of California to the heart of the Rocky Mountains in Colorado, traverses the Southern Basin and Range, Colorado Plateau and Rocky Mountain provinces. We hypothesize that changes in the topographic character of the river profile as well as the adjacent drainage areas correspond to differences in bedrock geology, tectonic genesis, ongoing faulting, and drainage reorganization events that themselves may be tectonically influenced. We test this hypothesis through the use of a quantitative topographic analysis that extracts information about the topographic roughness organization, grain orientation, and spectral power. The analysis is applied at two scales; for the regional analysis a 30-arc-second resolution DEM is used, and areas of particular interested are also evaluated with an analysis of a 3-arc-second DEM. A particular topographic feature of interest is the knickpoint in river gradient at Lee's Ferry, just north of the Grand Canyon at the boundary between the Marble and Glen Canyons. We hypothesize that the river system is a sensitive gauge to differential tectonism in the western US and that significant changes in topography character across this knickpoint offers a way to test the extent to which topographic features of Colorado River drainage are due to young tectonism or to more passive incision of a previously elevated plateau. Upstream from the knickpoint we find a strong topographic signal that correlates the Aspen anomaly and is indicative of active doming due to mantle magmatism and resulting buoyancy.
DE: 8107 Continental neotectonics (8002)
DE: 8175 Tectonics and landscape evolution
DE: 8178 Tectonics and magmatism
SC: Tectonophysics [T]
MN: Fall Meeting 2005