R8: Metamorphic rocks and tectonics

[R8-08] Blueschist facies impure metachert as remarkable oxygen- and overlooked water-carriers in the subduction zone

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

Keywords:subduction zone, metacherts, deep-fluids, mass transfer

Chemical compositions and mode of occurrence of HP minerals are measured to appreciate mass transfer by lawsonite-blueshist facies Mn-bg. metacherts from the Kurosegawa Belt in Yatsuhiro, Kyushu. Mn-bg. lawsonite is the strongest water budget with 10 wt% H2O content, and enables 3 wt% in a certain sample. Oxygen is remarkably carried by haematite, with the carriage 500 times larger than eclogite (Malaspina et al., 2012). These findings are to draw a minute, lively image of the subduction zone.