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Phase Relations in the System CaO-MgO-Al_2O_3-Cr_2O_3-SiO_2 at high pressures and temperatures.

Research Project

Project/Area Number 62460055
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 鉱物学(含岩石・鉱床学)
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

ONUMA Kosuke  Faculty of Science, Tohoku University, 理学部, 教授 (50000865)

Co-Investigator(Kenkyū-buntansha) FUJIMAKI Hirokazu  Faculty of Science, Tohoku University, 理学部, 助手 (90133933)
YOSHIDA Takeyoshi  Faculty of Science, Tohoku University, 理学部, 助手 (80004505)
AOKI Ken-ichiro  Faculty of Science, Tohoku University, 理学部, 教授 (00004276)
Project Period (FY) 1987 – 1988
Project Status Completed (Fiscal Year 1988)
Budget Amount *help
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥4,200,000 (Direct Cost: ¥4,200,000)
KeywordsPetrologic Model / Chromium / Lherzolite / Mantle / Phase Equilibria / Pyroxene / Plagioclase / 微量元素 / 岩石科学モテル系 / 岩石学的モデル系 / スピネル・レールゾライト / マントル / 部分熔融
Research Abstract

In the present study following resutls have been obtained.
(1) The effect of Cr on phase relations in the system Mg_2SiO_4-CaAl_2Si_2O_8-CaMgSi_2O_6-SiO_2, an important petrologic model, has been studied at 1 atm in air. Addition of minor amount of Cr (Cr_2O_3= 0.24 wt.%) gives a significant effect on the phase relations. The phase assemblage olivine + orthopyroxene + clinopyroxene + spinel, which is not stable in the Cr-free system, is observed. This assemblage corresponds to that of spinel lherzolite. The facts obtained indicate that the presence of very small amount of Cr lowers the transformation temperature from plagioclase lherzolite to spinel lherzolite.
(2) Since the phase relations of the system MgSiO_3-CaAl_2Si_2O_8 has been problematical, detailed reexamination was carried out, before the study of the effect of Cr in this system. The orthopyroxene present in this system does not have a composition on join MgSiO_3-CaAl_2Si_2O<@23 and the assemblage of olivine + orthopyroxene + anorthite + liquid has some temperature range, indicating that the syste is not ternary but belongs to quaternary system.
(3) The experiments on the join CaMgSi_2O_6-Mg_2SiO_2-CaAl_2Si_2O_8-0.2% MgCr_2O_4 has been performed at 10 kbar to understand the effect of Cr on the silicate system under high pressures. The primary field of clinopyroxene is enlarged and that of spinel is decreased compared with that in the Crfree system. This phenomena are probably due to the partitioning of trace element among the crystalline phases and liquid. More detailed studies are needed to understand this problem.

Report

(3 results)
  • 1988 Annual Research Report   Final Research Report Summary
  • 1987 Annual Research Report
  • Research Products

    (7 results)

All Other

All Publications (7 results)

  • [Publications] Kosuke Onuma: Journal of Mineralogy,Petrology and Economic Geology. 83. 405-417 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Kosuke Onuma;Hiromi Ito: Science Report of Tohoku University,Series 3. 16. (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Kosuke Onuma: "Effect of Cr on the liquidus phase relations in the system Mg<@D22@>D2SiO<@D24@>D2-CaMgSi<@D22@>D2O<@D26@>D2-CaAl<@D22@>2Si<@D22@>D2O<@D28@>D2-SiO<@D22@>D2 in air at l atm." Journal of Mineralogy, Petrology and Economic Geology. 83. 405-417 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Kosuke Onuma; Hiromi Ito: "Reexamination of the join MgSiO_3-CaAl_2Si_2O_8." Sience Report of Tohoku University, Series 3. 16. (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Kosuke,Onuma: Jour.of Mineralogy,Petrology and Economic Geology. 83. 405-417 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] Kosuke,Onuma;Hiromi,Ito: Science Report,Tohoku Univ.Series 3. 16. (1989)

    • Related Report
      1988 Annual Research Report
  • [Publications] Kosuke.Onuma: Journal of Mineralogy,Petrology and Economic Geology.

    • Related Report
      1987 Annual Research Report

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Published: 1987-04-01   Modified: 2016-04-21  

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