Equilibrium and Reaction of Mineral-water interaction in upper crust

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A sample chamber for environment controlled in-situ observation was designed and made for x-ray diffraction experiments under 200℃, and under-saturated condition (up to 1.55 MPa at 200℃) to investigate mineral-vapor equilibrium and reactions. An apparatus for higher temperature and pressure was designed to investigate under-and over-saturated conditions.Experiments : Cation exchanged smectite, Kunipia F by alkali metal ion, Li+-Cs+, alkali earth metal ion, Mg2+-Ba2+ and La3+were used to investigate swelling property in terms of cations up to 150℃. The swelling behavior of smectite with various cations for temperature rage up to 150℃Molecular simulations : We made a program to produce initial structures having surfaces with fluid phase. Molecular dynamics simulation programs, MXORTO/MXDTRICL, were updated for the very large systems. Using these programs on MPI parallel PC systems, MD simulations with more than 50,000 atoms systems became possible. We performed calculations to derive excess mixing enthalpy and diffusion constant of H20 and exchangeable cations in interlayer region of clay minerals. Using these programs, we performed some multi-phase complex systems, such as smectite with edge-water/aqueous solution (NaCl,CaCl2 etc.). serpentine group minerals-water/solution systems. MD calculations of zeolite surface-ammonium gas system revealed the dynamic process of ammonium molecules at and near channel windows in zeolite structures.Analysis : Combining the data by experiments and molecular simulation results, we analyzed the relation between structural change and adsorption behavior with equilibrium and non-equilibrium processes under various physico-chemical conditions.