R8: Metamorphic rocks and tectonics

[R8P-03] Impure metacherts, archives of multi-stage mineral growth, portray the shallower part of the subduction zone

*Wataru J YABUTA¹, Takao HIRAJIMA¹ (1. Grad. Sci., Kyoto Univ.)

Keywords:subduction zone, geo-fluids, lawsonite-blueschist facies

This study deals with multi-stage mineral growth recorded by lawsonite-blueshist facies metacherts from the Kurosegawa Belt in the Yatsuhiro area, Kyushu. First near-peak stage is represented by Mn-bg. lawsonite and other high pressure hydrous minerals and zig-zag shaped veins. Later post-peak stages are featured by ultra-oxidized and alkali-rich fluid activities which formed todorokite and Ba-bg. K-feldspar veins. These findings are to portlay the fluid activities in shallower part of a subduction zone.