HR: 1340h
AN: MR23B-0064    [Abstracts]
TI: Chemical Reaction Between Molten Iron and MgSiO3 at the Core-Mantle Boundary Condition
AU: * Sakai, T
EM: sakai@ganko.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Sendai 980-8578, Japan, Sendai, 980-8578 Japan
AU: Kondo, T
EM: tdskondo@mail.tains.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Sendai 980-8578, Japan, Sendai, 980-8578 Japan
AU: Terasaki, H
EM: terasaki@mail.tains.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Sendai 980-8578, Japan, Sendai, 980-8578 Japan
AU: Ohtani, E
EM: ohtani@mail.tains.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Sendai 980-8578, Japan, Sendai, 980-8578 Japan
AU: Endo, N
EM: nendo@jeol.co.jp
AF: Application and Research Center JEOL Ltd., Application and Research Center JEOL Ltd., Akishima 196-8558, Japan, Tokyo, 196-8558 Japan
AU: Kuba, T
EM: tkuba@jeol.co.jp
AF: Application and Research Center JEOL Ltd., Application and Research Center JEOL Ltd., Akishima 196-8558, Japan, Tokyo, 196-8558 Japan
AU: Suzuki, T
EM: tosuzuki@jeol.co.jp
AF: Application and Research Center JEOL Ltd., Application and Research Center JEOL Ltd., Akishima 196-8558, Japan, Tokyo, 196-8558 Japan
AU: Kikegawa, T
EM: takumi.kikegawa@kek.jp
AF: Japan Photon Factory, High Energy Accelerator Organization, Japan Photon Factory, High Energy Accelerator Organization, Tsukuba 305-0801, Japan, Tsukuba, 305-0801 Japan
AB: Chemical reaction between the mantle and core is an important process for dissolution of the light elements in the core and the anomalous seismic structure at the core-mantle boundary (CMB). A reaction between (Mg, Fe)SiO3 perovskite and metallic iron has been experimentally investigated using laser-heated diamond-anvil cell (LHDAC)[1]. It is essential to clarify that the chemical reaction and textural relationship between iron and post-perovskite[2] at the CMB condition. Powdered natural MgSiO3 enstatite from Sri Lanka and iron powder (99.5 %) were used for the starting material. We have conducted high-pressure experiments under the conditions of the CMB, up to 139(10) GPa and 3,000(200) K using LHDAC technique. In this condition, metallic iron was coexisted with post-perovskite, which was confirmed in situ X-ray diffraction studies at Photon Factory(KEK) in Tsukuba.We made detailed TEM observations of the textures and compositions of the metallic iron and post-perovskite coexisting in the run products. Compositional analysis indicates that a significant amount of oxygen up to 6.3 wt.% and silicon up to 4.0 wt.% are dissolved in metallic iron. The solubility of silicon and oxygen in metallic iron observed in this study is consistent with [3], it can readily account for the estimated density deficit of the core [4]. The present results strongly imply that both oxygen and silicon are the most plausible candidates of the light elements in the core. The dihedral angles between molten iron and post-perovskite from TEM images of the recovered sample from 139(10) GPa and 3,000(200) K was 67 degrees, it is inconsistent with previous study [3]. The required melt fraction to form an interconnected network of liquid iron (critical melt fraction) is around 2 vol.% [5], suggesting a small amount of metallic iron can be trapped at the core-mantle boundary. [1] e.g., Knittle and Jeanloz, Science, 1991 [2]Murakami et al., Science, 2004 [3]Takafuji et al., EPSL, 2004 [4]Anderson and Isaak, PEPI, 2002 [5]Bargen and Waff, JGR, 1986
DE: 3612 Reactions and phase equilibria (1012, 8412)
DE: 3924 High-pressure behavior
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005