Session outline

Solid Earth Sciences(S) Session Sub Category Complex & General(CG) Session ID S-CG14 Title Mixed volatiles in subduction zones; Physical and chemical properties and processes Short title Mixed volatiles in subduction zones Convener Name Bjorn Mysen Affiliation Geophysical Laboratory, Carnegie Inst. Washington Email bmysen@ciw.edu Co-convener 1. Name Eiji Ohtani Affiliation Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University Email ohtani@m.tohoku.ac.jp Co-convener 2. Name Dapeng Zhao Affiliation Department of Geophysics, Tohoku University Email zhao@aob.gp.tohoku.ac.jp International Symposium 'International Symposium' in addition to Scientific session. Language English Scope The principal volatiles in subduction zones and CO2 and H2O derived from devolatilization of carbonate and hydrous minerals in subducted oceanic crust and upper mantle. In the forearc region, highly reduced CH4 may be formed via deserpentinization of forarc mantle. Halogens (F and Cl) are can also be transported at least to upper mantle depth. Fluorine may, in fact, enhance the P-T stability of hydrous minerals. Release of volatiles causes changes in elastic properties of the residual devolatilized rocks, which, in turn, governs seismic velocities, density, shear strength, and compressibility. The intergranular pore fluid also affects these properties. Whether or not fluid forms an interconnected network is critical for these properties. Fluid interconnectivity also controls the extent to which the fluid fluxes melting in and above subducting slabs and the trace and isotopic signatures of the source materials of melting. Physical properties of magma affect style of eruption. These properties, in turn, are affected by H2O/CO2 and F/Cl abundance ratios. This session will focus on observations, experiments and theory to aid our understanding of 1.Relationship between fluid composition, pressure and temperature and connectivity of intergranular fluid. 2.Shear strength and elastic properties of volatile-bearing mineral assemblages 3.Pressure(depth)-temperature and redox-controlled stability of volatile-bearing minerals in subduction zones and beyond. 4.Melting phase relations and volatile compositions in subduction zones 5.Seismic activity and its relation to volatiles in minerals and in fluids and in melts. 6.Solubility and solution mechanisms of major, mineral, and trace elements in silicate-saturated mixed fluids. 7.Silicate-saturated fluids and volatile-saturated melts and alteration processes in subduction zones. 8.Volatiles and style of volcanic eruption Type of presentation Oral and Poster presentation Invited papers Stefano Poli (University of Milano, Italy), Bruno Reynard (Ecole Normal Superieur Lyons, France), Michihiko Nakamura (Tohoku University, Japan)