HR: 17:45h
AN: MR54A-08    [Abstracts]
TI: Formation of wadsleyite in a shock experiment - implications for the duration of shock events in meteorite parent bodies
AU: * Tschauner, O
EM: olivert@physics.unlv.edu
AF: High Pressure Science and Engineering Center, Department of Physics, UNLV, 4505 Maryland Parkway, Las Vegas, NV 89154, United States
AU: * Tschauner, O
EM: olivert@physics.unlv.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Asimow, P D
EM: asimow@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Ahrens, T J
EM: tja@gps.caltech.edu
AF: Lindhurst Laboratory of Experimental Geophysics, Seismological Laboratory, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Kostandova, N
EM: kostand@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Sinogeikin, S
EM: ssinogeik@hpcat.aps.anl.gov
AF: HPCAT, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439, United States
AB: We report the first observation of the high-pressure silicate phase wadsleyite in the recovery products of a shock experiment. Wadsleyite was detected by micro-X ray diffraction and EBSD. Wadsleyite grew from melt which formed by chemical reaction of periclase and silica during shock. Our findings show that the growth rate of high pressure silicate phases in shock-generated melts can be of the order of m/s and is probably not diffusion controlled. Our finding has important implications for the time scale of shock events recorded by meteorites and indicates that the presence of high pressure silicates found in shocked meteorites does not necessarily imply large impactor sizes. This work was supported by the NNSA Cooperative Agreement DOE-FC88-01NV14049 and NASA/Goddard grants under awards NNG04GP57G and NNG04GI07G. Use of the HPCAT facility was supported by DOE-BES, DOE-NNSA, NSF, DOD -TACOM, and the W.M. Keck Foundation. APS is supported by DOE-BES under Contract No. W-31-109-Eng-38.
DE: 3924 High-pressure behavior
DE: 3944 Shock wave experiments
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 6022 Impact phenomena (5420, 8136)
DE: 6040 Origin and evolution
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting