HR: 0800h
AN: U41B-0420    [Abstracts]
TI: Chemical equilibrium between molten iron and mantle minerals
AU: * Ozawa, H
EM: h-ozawa@geo.titech.ac.jp
AF: Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8551, Japan
AU: Hirose, K
EM: kei@geo.titech.ac.jp
AF: Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8551, Japan
AU: Hirose, K
EM: kei@geo.titech.ac.jp
AF: Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan
AB: The molten outer core may be in chemical equilibrium, at least with the bottom thin layer of the mantle, which may be comprised mainly of (Mg,Fe)SiO₃-rich perovskite or post-perovskite and (Mg,Fe)O ferropericlase. The element partitioning data between molten iron and these mantle minerals at high pressure and temperature are important to constrain the chemical compositions of the liquid core and the lowermost mantle. The element partitioning between perovskite/post-perovskite and molten iron and between ferropericlase and molten iron has been studied at high pressures (e.g., Takafuji et al., 2005 GRL; Sakai et al., 2006 GRL; Asahara et al., 2007 EPSL). Here we examined the chemical equilibrium between three phases, perovskite/post-perovskite, ferropericlase, and molten iron to the core-mantle boundary condition by using the laser-heated diamond-anvil cell techniques. A starting material was prepared as a powder mixture of iron metal and gel with a composition of (Mg_0.9Fe_0.1)₂SiO₄. Mineral assemblage was confirmed by in-situ synchrotron X-ray diffraction measurement at high pressure and temperature at BL10XU of SPring-8. The chemical compositions of coexisting perovskite/post-perovskite, ferropericlase, and quenched liquid iron were determined with analytical transmission electron microscope. A thin section of the recovered sample was obtained parallel to the compression axis by Ar-ion milling method using Ion Slicer (JEOL EM-09100 IS). Results demonstrate that the dissolution both of oxygen and silicon into a liquid metal is enhanced with increasing pressure. We will discuss the chemical compositions of the outer core and the bottom of the mantle based on the present experimental results.
DE: 1015 Composition of the core
DE: 1025 Composition of the mantle
DE: 3612 Reactions and phase equilibria (1012, 8412)
DE: 3630 Experimental mineralogy and petrology
DE: 3924 High-pressure behavior
SC: Union [U]
MN: 2007 Fall Meeting