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.
|Number of pages||8|
|Publication status||Published - Dec 1 1997|
- Oeyama ophiolite
- Sangun-Renge metamorphic belt
- Serpentinite melange
ASJC Scopus subject areas
- Geochemistry and Petrology