No abstract

Glaucophane-epidote eclogite occurs in the eclogitic unit of the Omi serpentinite mélange, SW Japan. The eclogite has a peak mineral assemblage of garnet omphacite glaucophane epidote quartz rutile phengite. A P-T pseudosection for a bulk composition appropriate to the eclogite has been calculated using the THERMOCALC. program in the model system Na O-CaO-FeO-MgO-Al O-SiO-H O NCFMASH with quartz and water in excess. In the calculated phase diagram, a trivariant field of garnet omphacite glaucophane zoisite occurs within the high-pressure divariant field of garnet omphacite glaucophane hornblende sensu lato zoisite-it is consistent with the previous P-T estimation of peak metamorphism at T and P. GPa. The P-T pseudosection and average-P calculations using THERMOCALC reveal a significant pressure gap between two contrasting high-grade rocks in the eclogitic unit and the non-eclogitic unit. The glaucophane-epidote eclogite may have experienced higher pressure relative to the non-eclogitic paragonite-garnet amphibolite characterized by a trivariant field of garnet paragonite hornblende sensu lato zoisite. Considering inferred thermal structure of present-day subduction zones, glaucophane-epidote eclogite may record subduction metamorphism of young and warm slab.

No abstract

No abstract