HR: 0830h
AN: T11C-0415    [PDF]
TI: Behavior and Elastic Properties of Mantle Perovskites
AU: * Li, B
EM: Baosheng.Li@sunysb.edu
AF: Mineral Physics Institute, SUNY Stony Brook, Stony Brook, NY 11794 United States
AU: Kung, J
EM: jkung@notes.cc.sunysb.edu
AF: Mineral Physics Institute, SUNY Stony Brook, Stony Brook, NY 11794 United States
AU: Zhang, J
EM: jzhang@lanl.gov
AF: Las Alamos National Lab, LANSC, Las Alamos, NM 87545 United States
AU: Uchida, T
EM: uchida@cars.uchicago.edu
AF: GSECARS, Univeristy of Chicago, Chicago, IL 60637
AU: Wang, Y
EM: Wang@cars.uchicago.edu
AF: GSECARS, Univeristy of Chicago, Chicago, IL 60637
AB: Behavior and elastic properties of Earth minerals as a function of pressure and temperature are in great need in interpreting seismic discontinuities and tomographic images. Advanced ultrasonic techniques in conjunction with state-of-the-art synchrotron facilities allow us to conduct simultaneous measurements of sound velocities, crystal structure and unit cell parameters, and rheological properties of candidate materials to P greater than 25 GPa and/or T around 1600K in the laboratory. Recently, we have applied these techniques to the study of many mantle phases, including olivine, wadsleyite, calcium silicate perovskite(s), and magnesium silicate perovskite. For the unquenchable calcium silicate perovskite, a hot-pressed wollastonite sample was used as starting material. Fully transformation from amorphized wollastonite to cubic perovskite phase was obtained at about 14 GPa 1200K as confirmed by X-ray diffraction data. Travel times, X-ray images of sample and X-ray diffraction spectra were collected along multiple heating/cooling cycles at various pressures during decompression. We observed an anomalous behavior of P and S wave velocities at high pressure and high temperature, which might be caused by the phase transformation as, proposed in some recent studies. Unfortunately, the X-ray diffraction data collected using the energy dispersive method has very limited resolution to confirm such a phase transition. Following similar procedures as described above, measurements of P and S wave velocity on magnesium silicate perovskite phase have been extended to P greater than 25 GPa at ambient temperature. Combining these new measurements with our previous data to 9 GPa 873K, the pressure and temperature derivatives of the elastic moduli are determined. These new results allow us to investigated the visibility of calcium silicate perovskite in the lower mantle as well as velocity profiles in the lower mantle.
DE: 3900 MINERAL PHYSICS
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
SC: Tectonophysics [T]
MN: 2003 Fall Meeting