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1997 Fiscal Year Final Research Report Summary

High Pressure Phase Transformations Down to the Lower Mantle Conditions and Implications for the Nature of the Seismic Discontinuities.

Research Project

Project/Area Number 07454105
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionEhime University

Principal Investigator

IRIFUNE Tetsuo  Ehime Univ., Fac.of Science Professor, 理学部, 教授 (80193704)

Co-Investigator(Kenkyū-buntansha) YOSHIOKA Shoichi  Kyushu Univ., Fac.of Science Associate Professor, 理学部, 助教授 (20222391)
INOUE Toru  Ehime Univ., Fac.of Science Research Associate, 理学部, 助手 (00291500)
Project Period (FY) 1995 – 1997
Keywordspostspinel phase transition / seismic discontinuity / synchrotron radiation / lower mantle / high pressure experiments / high pressure phase transition
Research Abstract

High pressure and high temperature experiments have been made on mantle materials using both quench method and in situ X-ray diffraction measurement. The phase transformations in a pyrolite composition were studied by the former method at pressures to 28 GPa and temperatures along a representative mantle geotherm.It was demonstrated that iron partitioning of the coexisting phases in this composition affects significantly the width of the pressure interval between the modified spinel and spinel phases of olivine, which is consistent with the nature of the 410km discontinuity revealed by the recent seismological studies. On the other hand, we presented some data on the partitioning of iron between perovskite and magnesiowustite under the lower mantle conditions, and showed that the iron partition coefficient approaches unity with increasing pressure as a result of the increase of aluminum in the perovskite phase. The sharpness of the 660km seismic is discussed on the basis of these experimental data.
The phase boundary between spinel and the postspinel phase has been determined by in situ X-ray measurements using a combination of the synchrotron source (SPring-8) and a multianvil device. The boundary was determined at temperatures up to about 2000゚C,demonstrating that the postspinel phase boundary has a negative Clapeyron slope as estimated by quench experiments and thermodynamic analyzes. The boundary was located at about 21 GPa, at 1600゚C,which is about 2GPa lower than the earlier estimations based on other high pressure studies.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 入船 徹男: "地球超深部からの手紙" 科学. 67. 530-533 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] J.Ando et al.: "Evaluation of the non-hydrostatic stress produced in a multanvil high pressure apparatus" Physics and Chemistry of Minerals. 24. 139-148 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Yutani et al.: "Compressibility of calcium ferrite-type MgAl_2O_4." Physics and chemistry of Minerals. 24. 340-344 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Irifune et al.: "Phase transformations in serpentine and transportation of water into the lower mantle." Geophysical Research Letters. 25. 203-206 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Irifune et al.: "The postspinel phase boundary in Mg_2SiO_4 determined by in situ x-ray diffraction." Science. 279. 1698-1700 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Irifune et al.: "Iron partitioning in a pyrolite mantle and nature of the 410km seismic discontinuity" Nature. (印刷中). (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Irifune, T.: "A letter from deep in the Earth's interior." KAGAKU. 67. 530-533 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ando, J.: "Evaluation of the non-hydrostatic stress produced in a multianvil high pressure apparatus." Physics and Chemistry of Minerals. 24. 139-148 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yutani, M: "Compressibility of calcium ferrite-type MgA1204." Physics and Chemisty of Minerals. 24. 340-344 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Irifune, T.: "Phase transformations in serpentine and transportation of water into the mantle" Geophysical Resereh Letter. 25. 203-206 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Irifune, T.: "The postspinel phase boundary in Mg2SiO4 determined by in situ x-ray diffraction" Science. 279. 1698-1700 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Irifune, T.: "Iron partitioning in a pyrolite mantle and nature of the 410km seismic discontinuity." Nature. (in press). (1988)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-16  

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