3:00 PM - 3:15 PM
[SCG60-12] Inputs of Argon on oceanic plate at subduction zones
Keywords:Argon, Oceanic plate, Mantle, Equation of state
In this study, we used density functional theory to investigate the melting temperature and thermal pressure of Ar. We also performed the high-pressure experiments to determine the room-temperature equation of state for Ar. The combination of the first-principles molecular dynamics calculations and the high-pressure experiments led us to determine reliable physical properties, such as the equation of state and the melting temperature, over a wide range of pressures and temperatures.
The equation of state of Ar has been investigated to 382 GPa and 3000 K using the diamond anvil cell experiments and the first-principles molecular dynamics method. A large volume dependence of the thermal pressure of Ar was revealed at pressures higher than 200 GPa. A significant temperature dependence of the calculated effective Grüneisen parameters was confirmed at high pressures. This indicates that the conventional approach to analyze thermal properties using the Mie-Grüneisen approximation is likely to have a significant uncertainty in determining the equation of state for Ar, and that an intrinsic anharmonicity should be considered to analyze the equation of state. A melting temperature of Ar was estimated from calculation data, and a significant pressure dependence was confirmed. If the pressure-temperature path of the subducted slab is lower than critical condition, ~750 K and ~7.5 GPa, solid Ar can be carried down into the deep mantle. Melting of solid Ar in the upwelling mantle plume occurs at the bottom of the transition zone.