Melting relations of the hydrous primitive mantle in the CMAS-H2O system at high pressures and temperatures, and implications for generation of komatiites

Y. Asahara, Eiji Otani

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

The hydrous phase relations of primitive mantle compositions in the CaO-MgO-Al2O3-SiO2-H2O system with 1, 2, and 5 wt.% H2O have been investigated at 4, 6.5, and 8 GPa. The stability field of orthopyroxene in the residue expands with increasing H2O content at 4-8 GPa. Dissolution temperature of garnet decreases more rapidly than that of the other phases at 4 and 6.5 GPa. The dissolution curves of garnet and pyroxenes cross at 6 GPa and 1700°C in the 2 wt.% H2O-bearing system. Garnet is stable until high degree of melting at 8 GPa. Compositions of aluminum depleted komatiites are consistent with the liquid formed by more than 30% melting of the primitive mantle with H2O up to 5 wt.% at 8 GPa. Aluminum undepleted komatiite can be formed by more than 50 wt.% melting of dry and wet primitive peridotite (with water up to 2 wt.% H2O) at around 4-6 GPa. Variation in chemistry of komatiites might be explained by partial melting of primitive mantle with various water contents.

Original languageEnglish
Pages (from-to)31-44
Number of pages14
JournalPhysics of the Earth and Planetary Interiors
Volume125
Issue number1-4
DOIs
Publication statusPublished - 2001 Jan 1

Keywords

  • CMAS system
  • High pressure and temperature
  • Hydrous condition
  • Komatiite
  • Melting
  • Primitive mantle

ASJC Scopus subject areas

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

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