CSEDI: Experimental Constraints on Dynamic Processes in Earth's Core

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The transport properties of iron alloys are central to the understanding ofdynamic processes in the Earth's core, including convective motions in theouter core (which drive the geodynamo) and solid-state deformation in theinner core, which may be responsible for the observed seismic anisotropy.To better understand these processes the PIs propose to conductexperimental studies of diffusional transport in iron at high pressure (upto 27 GPa). Rates of diffusion of several chemical species (Fe, S, O, andOs) will be measured in both liquid iron and in high-pressure solid phases(fcc and hcp). The experiments will extend to significantly higherpressures than have been examined previously and will provide a more securebasis for extrapolating diffusion rates and diffusion-related properties tothe conditions of the core. The results will lead to a betterunderstanding of inner core rheology and mechanisms for producinganisotropic textures; the viscosity and role of compositional convection inthe outer core; and the spatial distribution of osmium isotopes and otherchemical species within the core.