HR: 0800h
AN: G11A-0782    [Abstracts]
TI: Comparison of the Plio-Pleistocene and Quaternary transtensive deformation structures along the Pacific-North American Plate boundary, Eastern Sierra region, southwestern Inyo County, California
AU: * Jayko, A S
EM: ajayko@usgs.gov
AF: u. S. Geological Survey, 3000 East Line St, Bishop, CA 93514 United States
AB: This paper provides a description of the Late Neogene and Quaternary Pacific-North American of plate boundary deformation along the southeast margin of the Sierra Nevada block and southwest margin of the Great Basin province, Inyo County, California. Offset flood basalts, lacustrine deposits and peneplain remnants provide excellent marker horizons for constraining the timing, magnitude and orientation of crustal deformation. In addition, Quaternary fault scarps are well exposed in the arid basins of the region and there has been extensive work on Quaternary slip rates during the last 25 years. Progressive deformation, and successive abandonment of structures has been recognized between the early Pliocene (~6 Ma) and the Holocene. Several poorly organised shear zones with apparently low deformation rates resulting in poorly defined and discontinuous fault zones have been identified within the intermontane regions. The orientation of small-scale topographic basins within the intermontane regions provides useful indicators of the geometry of intrablock strain and locally show pervasive kilometer-scale intrablock deformation of Plio-Pleistocene age. The more laterally continuous NW trending faults of Middle and Late Quaternary age, even those near and bounding the range fronts are commonly steeply dipping, about 75-85 degrees, with mostly strike-slip (~60-80%) to dip-slip displacement, consistent with the regional transtensive plate boundary setting.
DE: 7221 Paleoseismology
DE: 8107 Continental neotectonics
DE: 8159 Rheology--crust and lithosphere
DE: 1206 Crustal movements--interplate (8155)
DE: 1242 Seismic deformations (7205)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting