2000 Fiscal Year Final Research Report Summary
Phase equilibria and thermodynamic, properties of granulite facies minerals.
| Project/Area Number |
11640481
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Ehime University |
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Principal Investigator |
KAWASAKI Toshisuke Ehime University, Faculty of Science, Professor, 理学部, 教授 (50136363)
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| Project Period (FY) |
1999 – 2000
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| Keywords | ultra high-temperature granulite / orthopyroxene-garnet geothermometry / Ol+Cpx / Ca-Mg olivine / Opx+Spr+Sil / Opx+Spr+Qtz / lower crust / thermodynamic properties |
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| Research Abstract |
1. The theoretical and experimental investigations were carried out on the Ca-Fe-Mg partitioning between olivine and clinopyroxene and on the miscibility of Ca-Mg olivine. Both olivine and clinopyroxene can be approximated as the two-site asymmetric regular solution cooperating intracrystalline exchange equilibria. The Fe-Mg distribution coefficient increases with the Ca content, Fe/(Fe+Mg) of the system and h pressure, but the increase with pressure is very small. The solvus of the Ca-Mg olivine becomes narrow with pressure due to the negative excess volume of this solid solution.
2. The high pressure experiments were carried out to constrain the phase relations in the Mg_3Al_2Si_3O_<12>(pyrope composition) and (Mg_<0.75>, Fe_<0.25>)_3Al_2Si_3O_<12>(Prp_<75> composition) systems. The system equivalent to the Mg-rich garnet composition never directly break down to the low-pressure phase assemblages without any garnet phases, and has an intermediate P-T field including garnet + orthopyroxene + sillimanite + quartz, as well as garnet + orthopyroxene + sapphirine + quartz as decreasing pressure.
3. High pressure experiments reveals that an orthopyroxene granulite from McIntyre Island, Enderby Land, East Antarctica experienced retrograde metamorphism at 11.2 kbar and 895℃ and subsequently passed at a certain pressure between 10.9 kbar and 11.4 kbar at 873℃.
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Research Products
(4 results)
