JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Oral

S (Solid Earth Sciences) » S-MP Mineralogy & Petrology

[S-MP43] [JJ] Brittle-Ductile Transition and Supercritical Geofluids for Crustal Energy in Island Arc

Tue. May 23, 2017 3:30 PM - 5:00 PM 202 (International Conference Hall 2F)

convener:Noriyoshi Tsuchiya(Graduate School of Environmental Studies, Tohoku University), Hiroshi Asanuma(AIST), Yasuo Ogawa(Volcanic Fluid Research Center, School of Science, Tokyo Institute of Technology), Chairperson:Hiroshi Asanuma(AIST), Chairperson:Noriyoshi Tsuchiya(Graduate School of Environmental Studies, Tohoku University)

3:30 PM - 3:45 PM

[SMP43-07] Molecular dynamics simulations of NaCl-H2O fluid at elevated temperatures and pressures

★Invited papers

*Hiroshi Sakuma1, Masahiro Ichiki2 (1.National Institute for Materials Science, 2.Tohoku University)

Keywords:Supercritical fluid, Electrical conductivity, Density, Dielectric constant, Salt water

Fluids in the crust have large effects on the mass transfer, heat transport, and physicochemical properties of rocks. We have investigated the physical properties of aqueous fluids for developing the database used to model the distribution of fluids based on the geophysical observations. This study contributes to understanding the fundamental physical chemistry for characterizing the properties of aqueous fluids. Major components of fluid in the crust are estimated to be H2O, NaCl and CO2. Here we discuss the properties of NaCl-H2O fluid.
Density and electrical conductivity of NaCl-H2O fluids were calculated by classical molecular dynamics (MD) simulations from 673 to 2000 K, 0.2 to 2 GPa, and 0 to 10 wt% NaCl (to 22 wt% for the density) [1, 2]. These wide ranges of temperature, pressure, salt concentrations can be sufficient to discuss the fluids in the crust. Some highly conductive zones in the crust observed by the magnetotelluic technique can be interpreted by the presence of NaCl-H2O fluid with the salinity lower than 7.0 wt%.
Our MD simulations can provide a plausible model to explain the density, electrical conductivity, dielectric constant of the fluid by the behavior of ions and H2O molecules in the fluid. The behavior is discussed for developing the physical chemistry of aqueous fluids at elevated temperatures and pressures.

Sakuma and Ichiki (2016) Geofluids, 16, 89-102.
Sakuma and Ichiki (2016) J. Geophys. Res. Solid Earth, 121, 577-594.