HR: 0800h
AN: GP11A-0009    [Abstracts]
TI: Paleomagnetic Results From Early Cretaceous Basalts and Sediments of the Trans-Baikal Region, Southeastern Siberia
AU: * Zhao, X
EM: xzhao@pmc.ucsc.edu
AF: Department of Earth Sciences University of California, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Coe, R S
EM: rcoe@pmc.ucsc.edu
AF: Department of Earth Sciences University of California, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Gordienko, I V
EM: gord@pres.bsc.buryatia.ru
AF: Geological Institute Siberian Branch of Russian Academy of Sciences, 8, Sakhyanova Street, Ulan-Ude, 670047 Russian Federation
AU: Metelkin, D V
EM: metelkin@uiggm.nsc.ru
AF: Paleomagnetic Group UIGGM SB RAS, Akademik Koptug ave. 3, Novosibirsk, 630090 Russian Federation
AB: The Cretaceous was a time of tectonic reorganization of the globe. This study focuses on Early Cretaceous volcano-sedimentary sections of Thikhoi-Khilok, Borgoi, and Uda basins of the Trans-Baikal Region, Southeastern Siberia. We wonder what it can tell us about tectonic displacements and rotations of the region and intraplate motions within central Asia. New paleomagnetic results have been obtained from 12 dated Cretaceous basaltic lava flows and one sandstone site exposed in these basins. Progressive thermal and AF demagnetization removed a secondary magnetization, after which the characteristic component (ChRM) is isolated and decays toward the origin. The mean ChRM directions pass reversal, conglomerate, and fold tests. The corresponding paleomagnetic pole is not statistically different from the 95-130 Ma reference pole of Besse and Courtillot (2002) in terms of paleolatitude. About 10 degrees clockwise rotation in declination, only marginal statistically significant, is indicated by the data. Our data thus suggest that the southeastern margin of the Siberian Platform appears not to have rotated significantly relative to the platform itself and the Eurasian reference poles for the Cretaceous period are appropriate for Siberia. The new paleomagnetic evidence supports our Russian colleague~{!/~}s belief that sinistrial-strike slip motion may have existed in the Transbaikalia region during Late Mesozoic, which may lead to the interplate magmatic activities.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1599 General or miscellaneous
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005