2017年5月20日(土) 10:45 〜 12:15 A08 (東京ベイ幕張ホール)

コンビーナ:Mysen Bjorn(Geophysical Laboratory, Carnegie Inst. Washington)、大谷 栄治(東北大学大学院理学研究科地学専攻)、岩森 光(海洋研究開発機構・地球内部物質循環研究分野)、McCammon Catherine(Bayerisches Geoinstitut, University of Bayreuth)、座長:McCammon Catherine(Bayreisches Geoinstitut)

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.