Anisotropic diffusion creep in postperovskite provides a new model for deformation at the core-mantle boundary.

ABSTRACT: The lowermost portion of Earth's mantle (D″) above the core-mantle boundary shows anomalous seismic features, such as strong seismic anisotropy, related to the properties of the main mineral MgSiO3 postperovskite. But, after over a decade of investigations, the seismic observations still cannot be explained simply by flow models which assume dislocation creep in postperovskite. We have investigated the chemical diffusivity of perovskite and postperovskite phases by experiment and ab initio simulation, and derive equations for the observed anisotropic diffusion creep. There is excellent agreement between experiments and simulations for both phases in all of the chemical systems studied. Single-crystal diffusivity in postperovskite displays at least 3 orders of magnitude of anisotropy by exp

SUBMITTER: Dobson DP 

PROVIDER: S-EPMC6936715 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature