[S-IT26] [EE] Fluid-mediated processes and properties near convergent plate boundaries

Sat. May 20, 2017 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL7)

Subduction of plates near convergent plate boundaries, causing earthquakes, metamorphism and volcanism, is a unique process that distinguishes the Earth from other terrestrial planets. Subduction also plays a major role in the long-term evolution of Earth, such as continental growth and global material cycling.

Volatiles such as water and carbon dioxide in subduction zone environments are key to understanding these processes. Release of volatiles from subducting slabs reactions causes changes in bulk composition, volume, and elastic properties of the residual devolatilized rocks as well as changes the rocks through which released fluids migrate. Those properties, together with the intergranular pore fluid, govern the physical-chemical structure (seismic velocities, density, shear strength, and compressibility) and the dynamics (subduction motion, mantle flow, fluid migration, and melting). For example, fluid interconnectivity controls the extent to which the fluid fluxes melting in and above subducting slabs, as well as viscosity structure in the mantle wedge. Fluid transport also causes changes in major element composition, phase relations, and trace and isotopic signatures, of slab materials and of the melting regions, affecting, therefore, physical properties and chemistry of arc magmas, and ultimately the continental crust. The devolatilized rocks also undergo significant modification in physical and chemical properties, and cycle back into the deep mantle, which may contribute to a global mantle structure and dynamics. Thus, these fluid-mediated changes cause a huge impact on a wide range of phenomena.

We welcome approaches including observations, experiments and theory to aid our understanding of fluid-mediated processes in and near subduction zones, bringing together contributions from material science, petrology, geophysics, tectonics, geodynamics, and Earth system science, to examine the causes and consequences of subduction.

[SIT26-P01] Noble gas and major element composition of deep groundwater in the fore-arc region of southwest Japan; widespread distribution of fluids dehydrated from the Philippine Sea Plate

*Noritoshi Morikawa¹, Kohei Kazahaya¹, Masaaki Takahashi¹, Akihiko Inamura¹, Hiroshi A Takahashi¹, Michiko Ohwada¹, Masaya Yasuhara^1,2, Tsutomu Sato¹ (1.Geological Survey of Japan, AIST, 2.RISSHO University)

[SIT26-P02] Characteristics of slab-derived fluids beneath Kii Peninsula, southwestern Japan inferred from seismic tomography

*Takuo Shibutani¹, Kazuro Hirahara¹ (1.Kyoto University)

[SIT26-P03] Major components and salinity of slab-derived fluids: insights from fluid inclusions in jadeitites and jadeite-quartz rocks

*Miki Shigeno¹, Yasushi Mori¹, Tatsuhiko Kawamoto², Tadao Nishiyama³ (1.Kitakyushu Museum of Natural History and Human History, 2.Kyoto University, 3.Kumamoto University)

[SIT26-P04] In situ X-ray diffraction studies of hydrous aluminosilicate at high pressure and temperature

Ryota Abe¹, Yuki Shibazaki², Shin Ozawa¹, Itaru Ohira¹, Hiromu Tobe¹, *Akio Suzuki¹ (1.Department of Earth and Planetary Materials Science, Faculty of Science, Tohoku University, 2.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University)

[SIT26-P05] In situ observation of wet solidus from xenoliths and its control on rheological structures of lithospheric mantle beneath Ichinomegata, NE Japan

*Yuto Sato¹, Kazuhito Ozawa¹ (1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo)

[SIT26-P06] Effects of temperature, melt, and volatile on polycrystal anelasticity: Toward the application to subduction zone

*Hatsuki Yamauchi¹, Yasuko Takei¹ (1.Earthquake Research Institute, The University of Tokyo)