HR: 16:45h
AN: T24A-04    [Abstracts]
TI: Collisional Tectonics of the Saint Elias Orogen, Alaska, Observed by GPS
AU: * Elliott, J L
EM: julie@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Freymueller, J T
EM: jeff@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Larsen, C F
EM: chris@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AB: The Saint Elias orogen of south central Alaska and the adjacent area of Canada is the highest coastal mountain range on earth, with peaks that exceed 6000 meters in elevation. It is located in the complex transition zone between transform motion along the Queen Charlotte-Fairweather fault system and subduction along the Aleutian Megathrust. The Yakutat terrane lies in the gap between the end of the Megathrust and the end of the transform system. Roughly 4 cm/yr of convergence is accommodated within the continental crust, onshore and possibly offshore, as the Yakutat terrane collides with southern Alaska. This collision provides the driving force behind the stunning topographic relief of the orogen. As part of the STEEP project designed to unravel the tectonic complexities of this region, we made GPS measurements at 47 sites in south central Alaska during the summer of 2005. Here we present results from 13 campaign GPS sites that had prior measurements. The span of measurements at these campaign sites range from one to twelve years. All of the sites show northwestward motion and uplift. The highest amounts of uplift occur at several coastal sites near Icy Bay where average rates surpass 24 mm/yr. Further north, sites along the Bagley Icefield display an average uplift rate of about 20 mm/yr. A significant portion of this uplift is caused by the melting of regional icefields and the redistribution of mass in large glacier systems such as the Bering Glacier. We also examine the impact of the Denali Fault earthquake on the rates of motion in this area.
DE: 1200 GEODESY AND GRAVITY
DE: 1209 Tectonic deformation (6924)
DE: 8102 Continental contractional orogenic belts and inversion tectonics
SC: Tectonophysics [T]
MN: Fall Meeting 2005