Contributions to Mineralogy and Petrology

, Volume 69, Issue 3, pp 245–247 | Cite as

High pressure phase transformations in the joins Mg2SiO4-Ca2SiO4 and MgO-CaSiO3

  • Lin -gun Liu
Article

Abstract

High pressure phase transformations for all the mineral phases along the joins Mg2SiO4-Ca2-SiO4 and MgO-CaSiO3 in the system MgO-CaO-SiO2 were investigated in the pressure range between 100 and 300 kbar at about 1,000 °C, by means of the technique involving a diamond-anvil press coupled with laser heating. In addition to the four end-members, there are three stable intermediate mineral components in these two joins. Phase behaviour of all the end-member components at high pressure have been reported earlier and are reviewed here. Results of this study reveal that the three intermediate components are all unstable relative to the end-members at pressures greater than 200 kbar. Ultimately, monticellite (CaMgSiO4) decomposes into CaSiO3 (perovskite-type)+MgO; merwinite (Ca3MgSi2O8) decomposes into Ca2SiO4(K2NiF4-type)+CaSiO3 (perovskite-type)+MgO; and akermanite (Ca2MgSi2O7) decomposes into CaSiO3 (perovskite-type)+MgO. Note that the decomposition reactions of all phases studied here result in the formation of MgO. Intermediate Ca-Mg silicates transform to pure Ca-silicates plus MgO, while pure Mg2SiO4 transforms to MgSiO3+MgO.

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Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • Lin -gun Liu
    • 1
  1. 1.Research School of Earth SciencesAustralian National UniversityCanberraAustralia

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