Mineralogy of Mantle Peridotite Along a Model Geotherm up to 700 Km Depth

  1. Murli H. Manghnani and
  2. Yasuhiko Syono
  1. Eiichi Takahashi and
  2. Eiji Ito

Published Online: 21 MAR 2013

DOI: 10.1029/GM039p0427

High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto

High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto

How to Cite

Takahashi, E. and Ito, E. (1987) Mineralogy of Mantle Peridotite Along a Model Geotherm up to 700 Km Depth, in High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto (eds M. H. Manghnani and Y. Syono), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM039p0427

Author Information

  1. Institute for Study of the Earth's Interior, Okayama University, Misasa, Tottori-Ken 682-02, Japan

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1987

ISBN Information

Print ISBN: 9780875900667

Online ISBN: 9781118664124

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Keywords:

  • Mineralogy and Crystal Chemistry;
  • Phase transformations;
  • High Pressure-High Temperature Research

Summary

In order to understand mineralogical constituents of the earth's mantle, a series of synthetic experiments was carried out using a natural garnet peridotite (PHN-1611). The experimental pressure temperature conditions were along a model geotherm which had a maximum pressure of 26 GPa (equivalent to 720 km in depth) and a maximum temperature of 1600°C. Quenched run products were analyzed with an X-ray diffractometer for phase identification and with scanning electron microscopes for textural relationships. Chemical compositions of coexisting phases were determined with EPMA. Important phase transformations that have been proposed to occur in the earth's mantle (α to β, β to γ, γ to perovskite (Pv) plus magnesiowüstite (Mw), and pyroxenes to majorite-garnet) are demonstrated to take place in the natural peridotite composition. Two additional phases were found to be present at pressures equivalent to more than 500 km in depth: 1) Ca-P, a Ca-rich phase which is probably an unquenchable, high-pressure polymorph of diopsidic pyroxene, and 2) Al-P, an aluminous phase with unknown crystal structure.