High pressure elasticity of FeCO3-MgCO3 carbonates

We have determined the elastic stiffness moduli of FeCO3 across the spin transition up to 60 GPa by inelastic X-ray scattering and density functional theory calculations. We have derived functions describing the dependence of the components of the elastic tensor of Mg1-xFexCO3 solid solutions on pressure and concluded that there is a linear dependence of the C11, C33, C44 and C14 moduli on the composition parameter x. The elastic tensors were employed to calculate the sound velocities and velocity anisotropies of Mg1-xFexCO3. These results allow an assessment of the potential seismic signature of deep mantle carbonates.