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

铁合金的输运特性是理解地核动态过程的核心，包括外核的对流运动(驱动地球发电机)和内核的固态变形，这可能是观测到的地震各向异性的原因。为了更好地了解这些过程，PI建议对高压(高达27 Gpa)下铁的扩散输运进行实验研究。将测量几种化学物种(Fe、S、O和Os)在液态铁和高压固相(fcc和hcp)中的扩散速度。这些实验将扩展到比以前检查过的更高的压力，并将为外推扩散速率和与扩散相关的特性到核心条件提供更安全的基础。这些结果将有助于更好地了解内核流变学和产生各向异性结构的机制；外层成分对流的粘度和作用；以及内核内Os同位素和其他化学物种的空间分布。

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.