HR: 17:15h
AN: MR34A-06 INVITED    [Abstracts]
TI: Deformation of dry Olivine up to 11 GPa and 2100 K Using a Rotational Drickamer Apparatus
AU: * Kawazoe, T
EM: takaaki.kawazoe@yale.edu
AF: Yale Univesity, 210 Whitney Avenue, New Haven, CT 06511, United States
AU: Otsuka, K
EM: kazuhiko.otsuka@yale.edu
AF: Yale Univesity, 210 Whitney Avenue, New Haven, CT 06511, United States
AU: Tinker, D
EM: david.tinker@yale.edu
AU: Karato, S
EM: shun-ichiro.karato@yale.edu
AF: Yale Univesity, 210 Whitney Avenue, New Haven, CT 06511, United States
AU: Nishihara, Y
EM: yuu@geo.titech.ac.jp
AF: Tokyo Institute of Technology, 2-12-1 Ohokayama, Tokyo, 152-8551, Japan
AU: Jing, Z
EM: zhicheng.jing@yale.edu
AF: Yale Univesity, 210 Whitney Avenue, New Haven, CT 06511, United States
AU: Mookherjee, M
EM: mainak.mookherjee@yale.edu
AF: Yale Univesity, 210 Whitney Avenue, New Haven, CT 06511, United States
AB: Characterizing the pressure effects on plastic deformation of olivine is important for understanding mantle dynamics and evolution of the Earth. Although many experimental studies have been performed on olivine deformation, the magnitude of the pressure effects (activation volume, V*) remain controversial. We use the rotational Drickamer apparatus (RDA) to determine the pressure dependence of creep strength of olivine in the dislocation creep regime. Deformation experiments on dry hot-pressed polycrystalline San Carlos olivine have been conducted at 6-11 GPa, 1500-2100 K and strain rates of 0.9-7.4 × 10^-5 s^-1 using the RDA at X17B2, Brookhaven National Laboratory. Shear deformation experiments up to the strain of 0.45 were performed. Near steady-state deformation was observed after the shear strain of 0.04-0.24. The stress was measured from the dependence of lattice spacing on the orientation for (130), (131), (112), (122), (140), (211) and (241) planes, as well as dislocation densities. We found that (i) the strength of olivine at steady-state deformation at these pressures is much larger than those at lower pressures, (ii) the variation of stress values inferred from different lattice planes decreases with temperature. We conclude that the creep strength of olivine for dislocation creep increases significantly with pressure and that the plastic anisotropy in olivine decreases with temperature.
DE: 3630 Experimental mineralogy and petrology
DE: 3902 Creep and deformation
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 8162 Rheology: mantle (8033)
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting