| Project/Area Number |
11440161
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | The University of Tokyo (2000-2001)
Okayama University (1999) |
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Principal Investigator |
OZAWA Kazuhito Graduate School of Science, The University of Tokyo, Prof., 大学院・理学系研究科, 教授 (90160853)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Hiroko (NAGAHARA Hiroko) Graduate School of Science, The University of Tokyo, Prof., 大学院・理学系研究科, 教授 (80172550)
YAMASHITA Shigeru Okayama Univ., Institute for the Study of the Earth's interior, Associate Prof., 固体地球研究センター, 助教授 (30260665)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥13,700,000 (Direct Cost: ¥13,700,000)
Fiscal Year 2001: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1999: ¥8,700,000 (Direct Cost: ¥8,700,000)
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| Keywords | diffusion / chromite / olivene / spinel / evoporation |
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| Research Abstract |
In this research project, cation diffusion in olivine and Cr-Al spinel was examined by vacuum evaporation technique. The Fe-Mg interfiffusion and Ni tracer diffusion coefficients in olivine were determined at 1300〜1500℃ with gem-quality San Carlos olivine. The composition dependence and anisotropy were determined by applying a diffusion model with moving boundary. The diffusivity was found to be largest along the c-axis, intermediate along the b-axis, and smallest along the a-axis. At 1400℃, the interfifusion coefficient is estimated to be 8.7x10^<-15>±2.8(m^2/sec) along the c-axis. The anisotropy was also significant at 1500 and 1300℃, but there is a tendency that the diffusivities along a-and b-axis become similar at lower temperatures. Elemental diffusion in Cr-Al spinel was studied on octahedral chromian spinel from the Horokanai ophiolite at 1300〜1500℃. The spinel samples were evaporated incongruently developing outer reaction zone with low iron content and inner diffusion zone. By analyzing the compositional profile, the magnetite component was selectively evaporated through rapid diffusion promoted by point defects derived from reduction of ferric iron to ferrous iron. At 1300 and 1400℃, Al shows marked uphill diffusion, which clearly indicate that the Cr diffusivity is much slower than that of Al.
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