Thermodynamic Calculations Of Fe-Mg Interdiffusion In (Mg,Fe)(2)Sio4 Polymorphs And Perovskite

In this study, we show that the temperature and pressure dependence of Fe-Mg interdiffusion in (Fe,Mg)(2)SiO4 polymorphs (olivine, wadsleyite, and ringwoodite) and perovskite can be successfully reproduced in terms of bulk elastic and expansivity data through a thermodynamic model (so-called cB Omega model) that interconnects point defect parameters with bulk properties. Under dry and wet conditions, our calculated Fe-Mg interdiffusion coefficients D-calc(Fe-Mg) (particularly for anisotropic diffusivity in olivine), activation enthalpy h(act), and activation volume nu(act) over a wide range of geologically relevant temperatures (1000-2400K) and pressures (0-100 GPa) are consistent with the experimental ones when the uncertainties are considered. (C) 2015 AIP Publishing LLC.