HR: 0800h
AN: T41A-1285    [Abstracts]
TI: Kinematics of a continental triple junction in the western Tibetan plateau explains variation in structural style along the Karakoram fault
AU: * Raterman, N S
EM: raterman@geology.ucdavis.edu
AF: Department of Geology, University of California Davis, One Shileds Ave., Davis, CA 95616 United States
AU: Cowgill, E
EM: cowgill@geology.ucdavis.edu
AF: Department of Geology, University of California Davis, One Shileds Ave., Davis, CA 95616 United States
AU: Lin, D
EM: dinglin@mail.igcas.ac.cn
AF: Institute of Geology and Geophysics, Chinese Academy of Sciences, Deshengmenwai Street, Beijing, 100029 China
AB: Although microplate theories of continental deformation are commonly employed to develop kinematic models of entire continental collision zones, they are rarely used to investigate individual fault intersections within them. The India-Asia collision zone contains several large strike-slip faults that resemble plate boundaries providing an excellent opportunity to apply the principles of plate triple junctions to the intersection of major intracontinental fault systems. Using Landsat TM remotely sensed imagery, SRTM90 topographic data, and a new three dimensional visualization software package developed to interpret these datasets in unison, we created a neotectonic map of the intersection of the Altyn Tagh, Ghoza-Longmu Co, and Karakoram faults in the western portion of the India-Asia collision zone. Our mapping suggests that structural style along the Karakoram fault varies from essentially pure strike-slip in the north (37° to 34°N) to transtension in the south (34° to 32°N). This transition is coincident with a slight bend in the Karakoram fault that coincides with its intersection with the Ghoza-Longmu Co extension of the Altyn Tagh fault. Rigid block kinematic analyses using fault geometries derived from the neotectonic observations, reconnaissance field observations, and published geodetic and Quaternary slip-rates indicate that the variation in structural style along the Karakoram fault can be explained by differential motion between India, the Tianshuihai terrane, and the Tibetan plateau. Results from geodetically determined slip-rates imply a 6-8 Ma onset of left slip along the Ghoza - Longmu Co fault, bending and transtension along the central and southern Karakoram respectively, and extrusion of the Tibetan plateau at a rate of 3.7 mm/yr towards 107°. The correspondence between the neotectonic interpretations, kinematic analyses, and previous studies of the bedrock geology along the Karakoram fault demonstrate the applicability of microplate theories of continental deformation in assessing short-term (0-10 Myr) deformation patterns along intracontinental strike-slip fault systems.
DE: 8002 Continental neotectonics (8107)
DE: 8038 Regional crustal structure
DE: 8040 Remote sensing
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8158 Plate motions: present and recent (3040)
SC: Tectonophysics [T]
MN: Fall Meeting 2005