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 2.75 program in the model system Na
2O-CaO-FeO-MgO-Al
2O
3-SiO
2-H
2O (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=550-600ºC and
P>1.8 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.
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