HR: 0800h
AN: MR31A-0146    [Abstracts]
TI: Density and Fe-Mg partitioning changes in pyrolite to 50 GPa
AU: * Shinmei, T
EM: shinmei@sci.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan
AU: Irifune, T
EM: irifune@dpc.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan
AU: Sanehira, T
EM: sanehira@cars.uchicago.edu
AF: GeoSoilEnviroCARS, The University of Chicago, 9700 South Cass Avenue Building 434A, Argonne, Ill 60439, United States
AU: Nishiyama, N
EM: nishiyama@sci.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan
AU: Ken-ichi, F
EM: funakosi@spring8.or.jp
AF: Japan Synchrotron Radiation Research Institute, 1-1-1 Koto, Mikazuki-cho, Sayo-gun, Hyogo, 679-5198, Japan
AB: Pyrolite is a representative model of the Earth�fs mantle composition. Therefore, detailed studies of the phase relations and mineral physics properties in pyrolite over a wide pressure and temperature condition are required in order to understand the mineralogy and dynamics of the entire mantle. In this study, we have conducted in situ X-ray diffraction experiments to clarify the phase relations, Fe-Mg partitioning and density changes in pyrolite under the lower mantle conditions by using a combination of a multianvil apparatus and synchrotron radiation. In order to generate higher pressures equivalent to the lower mantle conditions, sintered-diamond cubes with truncated edge length of 1.5 mm were used as second stage anvils. MgSiO3-rich perovskite (MgPv), CaSiO3-rich perovskite (CaPv) and (Mg, Fe)O magnesiowustite (Mw) were observed from 28 to 47 GPa and at 1873 to 2073 K, which are based on the Tsuchiya�fs pressure scale of gold. This mineral assemblage is consistent with the previous studies, and the calculated bulk densities of pyrolite are close to those in PREM. We also observed the Fe-Mg partition coefficient between MgPv and Mw, KD=(Fe/Mg)Pv/(Fe/Mg)Mw, significantly decrease from 0.8 to 0.5 with increasing pressure in this above range.
DE: 3620 Mineral and crystal chemistry (1042)
DE: 3630 Experimental mineralogy and petrology
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting