Title: Roles of fluid in geochemical and geophysical processes in subduction zones and beyond

Abstract:
Fluid plays significant roles in diverse geochemical and geophysical processes in subduction zones and beyond (e.g. continents) but understanding of its roles is still challenging. In this talk, I will introduce how fluid controls demagnetization, heat flow, serpentinization, effective friction, and arc volcanism in subduction zones and intraplate volcanism in East Asia, unraveled via numerical models of fluid transport and associated reactions. First, the current evaluation of the demagnetization of the oceanic plate in the forearc, Northeast Japan, is explained by the pressure-driven demagnetization. The ongoing study suggests high effective frictional coefficients (~0.08) along the seismogenic zone in both Southwest and Northeast Japan. Second, the major volcanic history and current seismological and geochemical observations in Southwest Japan are explained by the spontaneous formation of the serpentinite layer at the slab interface beneath the forearc mantle. The ongoing study shows that the differences in the Quaternary volcanism and seismicity in Kyushu and Shikoku/Chugoku regions are attributed to the subtle differences in the subduction parameters. Last, the intraplate volcanoes in the Korean Peninsular and Eastern China resulted from the wet plumes detached from the stagnant slab. Ongoing study shows that flux melting at the 410 km discontinuity, driven by the dehydration of the wet plumes, forms ascending magma blobs as forms of solitary waves.