Melting and crystal-liquid partitioning in the system Mg2SiO4-Fe2SiO4 to 25 GPa

Eiji Ohtani, Koji Moriwaki, Takumi Kato, Kosuke Onuma

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Abstract

The melting relation of the Mg2SiO4-Fe2SiO4 system was studied at 8.5 GPa. Olivine and spinel melts incongruently into pyroxene and the liquid in the Fe2SiO4 rich portion of the system. Olivine melts congruently at least in the compositional range from (Mg0.5Fe0.5)2SiO4 to (Mg0.9Fe0.1)2SiO4, although the end member of Mg2SiO4 ently into periclase and the liquid at pressures above 8 GPa. The melting relation of (Mg0.9Fe0.1)2SiO4 was also studied up to 25 GPa. Olivine and modified spinel of this composition melt incongruently into anhydrous phase B and liquid, and into magnesiowustite and liquid at higher temperatures in the pressure range from 18 GPa to 23 GPa. Magnesiowustite is the liquidus phase at higher pressures at least up to 25 GPa in this composition. The partition coefficients between crystal and liquid are; DMg = 1.19(± 0.06), DSi = 0.88(± 0.04), DV = 0.63(± 0.16), DCr = 1.04(,.9p\ 0.21), DMn = 0.42(± 0.08), DFe = 0.76(± 0.07), DCo = 1.24(± 0.44), DNi = 1.46(± 0.81) for modified spinel; DMg = 1.41(± 0.06), DSi = 0.72(± 0.03), DV = 0.44(± 0.11), DCr = 0.94(± 0.12), DMn - 0.30(± 0.07), DFe - 0.56(± 0.06), DCo = 1.19(± 0.30), DNi = 1.65(± 0.87) for anhydrous phase B; DMg = 2.09(± 0.11), DV = 0.64(± 0.06), DCr = 1.01(± 0.05), DMn = 0.7(± 0.04), DFe = 1.45(± 0.08), DCo = 2.73(± 0.15), DNi = 4.72(± 0.25) for magnesiowustite. The present results of melting relations and partitioning are applied for the fractionation in the mantles of the terrestrial planets, such as Mars and Mercury.

Original languageEnglish
Pages (from-to)75-82
Number of pages8
JournalPhysics of the Earth and Planetary Interiors
Volume107
Issue number1-3
DOIs
Publication statusPublished - Apr 15 1998

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All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

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