Ab initio study of the elastic behavior of MgSiO3 ilmenite at high pressure

Abstract. We investigate the athermal high pressure be-havior of the elastic properties of MgSiO3 ilmenite up to 30 GPa using the ab initio pseudopotential method. Our results at zero pressure are in good agreement with single-crystal elasticity measurements. The elastic anisotropy is shown to decrease slightly under compression and hence to remain substantial (25 to 20 % shear wave anisotropy and 16 to 10 % longitudinal wave anisotropy) over the pressure regime studied. The directions of fastest and slowest wave propagation are found to change slightly with pressure as determined by the pressure dependence of c14 and c25. Com-parisons with the elastic behavior of other deep transition zone phases such as ringwoodite and garnet show that il-menite is likely to be the fastest and most anisotropic min-eral in this region. Large contrasts ( 10%) in velocities and densities between ilmenite and garnet are suggested to be signicant for the interpretation of lateral structure in the transition zone. 1