HR: 1330h
AN: V42A-0324    [PDF]
TI: Elasticity of Unquenchable High-Pressure Clinopyroxene at High Pressures and Temperatures
AU: * Kung, J
EM: jennifer.kung@sunysb.edu
AF: Mineral Physics Institute, ESS building, Stony Brook University, Stony Brook, NY 11790 United States
AU: Li, B
EM: Baosheng.Li@sunysb.edu
AF: Mineral Physics Institute, ESS building, Stony Brook University, Stony Brook, NY 11790 United States
AU: Uchida, T
AF: Consortium for Advances Radiation Source, University of Chicago, Building 434, 9700 South Cass Ave., Argonne, Il 60439 United States
AU: Wang, Y
AF: Consortium for Advances Radiation Source, University of Chicago, Building 434, 9700 South Cass Ave., Argonne, Il 60439 United States
AB: A phase transformation in (Mg,Fe)SiO3, one of the common constituent of the Earth's crust and upper mantle, from orthorhombic (OEN) to monoclinic symmetry is likely to occur in the deeper portions of the upper mantle (Pacalo and Gasparik, 1990; Kanzaki, 1991). Angel et al. (1992) confirmed that the clinoenstatite phase above 8 GPa is an unquenchable high pressure monoclinic phase (HP-CEN), space group C2/c. Due to its unquenchable nature, this high pressure clinoenstatite has to be synthesized within its stability field in order to study its elasticity. The elasticity measurements were carried out using the ultrasonic technique in the large volume apparatus in conjunction with in-situ X-radiation techniques (X-ray diffraction and X-radiography). The experimental setup has made possible to monitor the length change of sample during experiment, as well as the measurements of travel times and density of the sample simultaneously. The starting material for the acoustic experiment was a well-sintered OEN polycrystalline specimen, which was hot-pressed at conditions of 5 GPa, 1000 degree C for an hour prior the experiment. After the OEN fully transformed to the HP-CEN at pressure of 13 GPa, 1000 degree C during the acoustic experiment, elasticity and X-ray data have been collected along a series of heating/cooling cycles at different pressures during the decompression. The data collection was stopped at 6.5 GPa because of the phase transition from HP-CEN to LP-CEN at lower pressure. The resulting bulk and shear moduli at different P-T conditions were treated as linear functions of both pressure and temperature with adjustable parameters: moduli at 6.5 GPa, room temperature, the pressure derivatives at constant temperatures, and the temperature derivatives at constant pressures. Compared with OEN (Flesch et al., 1998), our results show that the pressure derivatives of the bulk and shear moduli of HP-CEN are similar to those of OEN when the conditions of 6.5 GPa, room temperature. We also compared the elasticity of HP-CEN to those of olivine at high pressure and temperature (Li et al., 2003). Reference: Pacalo and Gasparik, J. Geophys. Res., 95, 15853-15858, 1990.Kanzaki, M.,Phys.Chem. Min., 17, 726-730, 1991. Angel et al., Nature, 358, 322-324, 1992. Flesch et al., Am. Miner. 83, 444-450, 1998. Li et al., submitted Phys. Earth, Plant. Inter., 2003.
DE: 1025 Composition of the mantle
DE: 3672 Planetary mineralogy and petrology (5410)
DE: 3900 MINERAL PHYSICS
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 8124 Earth's interior--composition and state (old 8105)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting