HR: 0800h
AN: U11A-0002    [Abstracts]
TI: Effects of Oxygen Fugacity and Temperature on Partitioning of Ni and Co Between Liquid Metal, Magnesium Silicate Perovskite and Magnesiowustite
AU: * Kawazoe, T
EM: takaaki.kawazoe@yale.edu
AF: Yale University, 210 Whitney Avenue, New Haven, CT 06511, United States
AU: * Kawazoe, T
EM: takaaki.kawazoe@yale.edu
AF: Tohoku University, Aramaki, Sendai, 980-8578, Japan
AU: Ohtani, E
EM: ohtani@mail.tains.tohoku.ac.jp
AF: Tohoku University, Aramaki, Sendai, 980-8578, Japan
AB: In the core formation stage, a magma ocean might have extended to the lower mantle depth, and Ni and Co might have been distributed throughout the magma ocean, solid lower mantle, and the Earthfs core. Although it is important to determine effects of oxygen fugacity (fO₂) and temperature on partition behavior of these elements between liquid iron and lower mantle minerals, it has not been well constrained because of its experimental difficulty. Partitioning of Ni and Co between liquid iron-rich metal and lower mantle minerals, such as magnesium silicate perovskite and magnesiowustite, was investigated at 26-27 GPa, 2680-3020 K and 1.15- 1.86 log units below the iron-wustite fO₂ buffer. The experiments have been achieved at such conditions using a Kawai-type apparatus and a cell assembly optimized for high-temperature generation. Our experiments revealed that partition coefficients of Ni and Co between liquid iron-rich metal and the lower mantle minerals decrease with increasing fO₂, whereas they have very week temperature dependence in the present temperature range. The present result makes it possible to evaluate Ni and Co abundance throughout the mantle for a plausible fO₂ and temperature. The mantle abundance of Ni and Co may be explained by the core formation in the deep magma ocean with a bottom pressure of around 65 GPa (corresponding to 1500 km depth).
DE: 3630 Experimental mineralogy and petrology
DE: 3924 High-pressure behavior
DE: 8115 Core processes (1213, 1507)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
DE: 8125 Evolution of the Earth (0325)
SC: Union [U]
MN: 2007 Fall Meeting