Sun. May 20, 2018 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Bjorn Mysen(Geophysical Laboratory, Carnegie Inst. Washington), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Jun Tsuchiya(愛媛大学地球深部ダイナミクス研究センター)

This session addresses how volatile species in the COHN system affect the geochemistry, mineralogy, and geophysics of the Earth and planetary interior from natural observations, laboratory experiments, and numerical modeling in the temperature, pressure, and oxygen activity range from the early stage of the planet formation to the present.
The COHN volatiles can be critical in zones of mantle upwelling and melting, in the fluid-enriched subduction zones, in the mantle transition zone, in the lower mantle to the core-mantle boundary, and in Earth and planetary cores. However, COHN volatiles affect properties and processes differently depending on their oxidation state, and terrestrial and planetary redox conditions vary in time and space. For example, properties of the upper mantle, which is often oxidizing and comprise CO2, H2O, and N2, will differ from those of the deeper mantle where more reducing conditions may stabilize H2O, H2, simple hydrocarbon, ammonia, hydrides, carbides, and nitrides. This difference is because reduced C- and N-bearing species may substitute for oxygen in silicate melts and minerals, whereas C- and N-bearing oxidizing species, such as CO2, H2O, and N2 do not.
This session will address how volatiles control the dynamic processes of Earth and planets, governed by their geophysical and geochemical properties, from geological and laboratory observations coupled with numerical modeling. The topics include (1) Stability relations, chemical and physical properties of crystalline, molten and fluid phases, and partitioning of COHN volatiles among these phases, (2) Stable isotopes, and their fractionation due to pressure and redox conditions, (3) Rheological properties of geomaterials, intergranular fluid, and fluid composition, (4) Seismicity and the influence of volatiles in various tectonic regions including subduction zones. (5) Effects of fluids and melts in numerical simulation of geo-tectonics.