Abstract
Omphacite (Jd46.1-52.0Aeo-8.4Aug48.o-51.2) and diopside (Jd4.3-6.3Ae0-0.4AUg93.6-95.6) coexist in a vein cutting an omphacitite block in a serpentinite melange of the Oeyama ophiolite, central Chugoku Mountains. The compositional gap between omphacite and diopside is significantly wider than for other omphacite-diopside pairs reported in the literature. The intergrowth texture of the omphacite-diopside vein suggests that the clinopyroxene pair was contemporaneously crystallized in the fracture from a Ca-bearing, alkali-rich fluid in a sub-solvus condition. Such a fluid may have been introduced from the surrounding serpentinized clinopyroxene-bearing harzburgite. The stability of omphacite and Al-rich pumpellyite in the matrix and the omphacite-diopside vein indicate that the earlier matrix recrystallization and later fracture filling may have both taken place under high-P-T condition during the melange-forming stage.
Original language | English |
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Pages (from-to) | 845-852 |
Number of pages | 8 |
Journal | Mineralogical Magazine |
Volume | 61 |
Issue number | 6 |
Publication status | Published - Dec 1 1997 |
Keywords
- Diopside
- Immiscibility
- Oeyama ophiolite
- Omphacite
- Sangun-Renge metamorphic belt
- Serpentinite melange
ASJC Scopus subject areas
- Geochemistry and Petrology