HR: 0830h
AN: S31D-0784    [PDF]
TI: Seismic Detection of the $\alpha$-$\beta$ Quartz Transition Provides Precise Temperature Estimation in the Tibetan Crust
AU: * Mechie, J
EM: jimmy@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, 14473, Potsdam Germany
AU: Sobolev, S V
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, 14473, Potsdam Germany
AU: Ratschbacher, L
AF: Institute for Geology, Technical University Freiberg, 09599, Freiberg Germany
AU: Babeyko, A Y
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, 14473, Potsdam Germany
AU: Jones, A G
AF: Geological Survey of Canada, 615 Booth Street, Ottawa, ON K1A 0E9 Canada
AU: Solon, K D
AF: ExxonMobil Exploration Company, GP-3, Room 348, Houston, TX 77060 United States
AU: Brown, L D
AF: Department of Earth and Atmospheric Sciences, Cornell University, 3124 Snee Hall, Ithaca, NY 14853 United States
AU: Zhao, W
AF: Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing, 100037 China
AB: In the deep crust, temperature, which is among the key parameters controlling lithospheric dynamics, is inferred by extrapolation from the surface using several assumptions that may well fail in regions of active tectonics and fluid migration. In the rare case that temperatures of $700\deg$C or higher are exceeded in the upper/middle continental crust composed of quartz-rich felsic rocks, the $\alpha$-$\beta$ quartz transition (ABQT) will occur, generating a measurable seismic signature and offering the possibility for precisely estimating temperature from the known ABQT phase diagram. Here it is shown that all expected seismic features of the ABQT are met by the boundary at 18-32 km depth below the INDEPTH III profile in central Tibet. Thus, this seismic boundary more probably represents the signature of (recent) geological processes rather than a lithological boundary.
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1242)
DE: 8102 Continental contractional orogenic belts
SC: Seismology [S]
MN: 2003 Fall Meeting