HR: 15:25h
AN: G43A-07    [Abstracts]
TI: Seismic implications of Arabia-Eurasia collision kinematics derived from geomorphic evidence of recent folding in northwest Iraq
AU: * Cowgill, E
EM: cowgill@geology.ucdavis.edu
AF: Department of Geology, University of California Davis, One Shields Ave, Davis, CA 95616 United States
AU: Sieh, K
EM: sieh@gps.caltech.edu
AF: Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Avouac, J
EM: avouac@gps.caltech.edu
AF: Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: The Arabia-Eurasia collision zone provides a rare opportunity to understand better the deformational behavior of the continental crust and lithosphere, particularly the extent to which such deformation is localized along a few major fault systems. Although such fault systems play a critical role in absorbing Arabia-Eurasia convergence in the western and eastern thirds of the orogen, their importance remains unclear in the central portion of the belt, because the surface expression of active deformation in this area has not yet been clearly established. Using along-track ASTER stereo imagery and a new three-dimensional visualization and mapping technique we developed for use with such data, we have discovered widespread geomorphic evidence of recent folding in the Taurus-Zagros Mountains of Turkey, Syria and Iraq. This discovery conflicts with long-standing kinematic models of the central portion of this mountain belt. To explain it we propose that the upper-crustal shortening reflected by the young fold belt is balanced at depth by underthrusting of Arabian basement along a north-dipping megathrust, in a style similar to that seen in the Himalayas and other fold-thrust belts around the world. Our three-dimensional, elastic-dislocation modeling of regional GPS data (1, 2) indicates that the megathrust is locked and elastically loaded by an obliquely creeping dislocation to the north that slips at 12.2 mm/yr towards S28°E. In addition, the East Anatolian Plateau is predicted to undergo a counterclockwise, vertical-axis, rigid-body rotation of ~0.9°/Myr relative to Eurasia. The lack of very large historical earthquakes along the proposed megathrust beneath the Taurus-Zagros ranges suggests that either there is significant risk of a major megathrust earthquake in northeastern Iraq, or that strain release occurs during some type of aseismic, slow-slip event.
DE: 1209 Tectonic deformation (6924)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8002 Continental neotectonics (8107)
DE: 8108 Continental tectonics: compressional
DE: 8164 Stresses: crust and lithosphere
SC: Geodesy [G]
MN: Fall Meeting 2005