CSEDI Collaborative Research: Experimental Constraints on the Chemistry and Evolution of Earth's Core

富铁六方密堆积（hcp）合金的化学，以及它在元素和同位素组成，对流和地核演化中的作用将被研究。共存的富铁hcp合金和熔体的组合物将在25 GPa的压力下测定。铁与少量的锇或钌形成合金，可以稳定金属的六方晶系结构;这种相被广泛认为与地核直接相关，但在以前的化学分配实验研究中无法获得。富铁六方晶系合金和熔体之间的微量元素分区在高压下的数据将提供深入了解亲铁元素的分布，作为重要的放射性同位素地质年代计，并将把所需的实验约束地球演化模型，涉及同位素签名进行从外核到表面。富铁hcp合金和熔体之间的主要元素，如Ni，S和O的分配将被用来约束固体内和液体外芯的组成，并将提高我们对芯中组成对流的驱动机制的理解。 拟议的研究将是第一个应用，其中铁合金专门稳定的hcp相在更适合的压力和温度，它可能会刺激进一步的实验研究hcp-Fe的物理和化学性质。此外，这项工作将展示高压实验和微量元素分析技术的结合，并应促进其在地球科学中的更广泛应用。拟议研究的结果将主要通过在科学文献中发表、参加科学会议以及在必要时通过影响更广的新闻媒体进行传播。

The chemistry of iron-rich hexagonal close packed (hcp) alloy, and its role in the elemental and isotopic composition, convection, and evolution of the Earth's core, will be studied. The composition of coexisting iron-rich hcp-alloys and melt will be determined at pressures to 25 GPa. The hcp structure of the metal will be stabilized by alloying Fe with a small amount of Os or Ru; this phase is widely thought to be directly relevant to the Earth's core but has been inaccessible in previous experimental studies of chemical partitioning. Data on trace element partitioning between Fe-rich hcp alloy and melt at high pressures will provide insight into the distribution of siderophile elements that act as important radioisotope geochronometers, and will place needed experimental constraints on models of Earth evolution that involve isotopic signatures to be carried from the outer core to the surface. The partitioning of major elements such as Ni, S, and O between Fe-rich hcp alloy and melt will be used to constrain the compositions of the solid inner and liquid outer core, and will improve our understanding of the driving mechanism for compositional convection in the core. The proposed research will be the first application in which Fe is alloyed specifically to stabilize the hcp phase at more amenable pressures and temperatures, and it may stimulate further experimental investigations into the physical and chemical character of hcp-Fe. Additionally, this work will demonstrate a combination of high-pressure experimental and trace element analytical techniques, and should stimulate its broader application in the geosciences. Results from the proposed study will be disseminated primarily through publication in the scientific literature, by participation at scientific conferences, and when warranted, through wider-reaching news outlets.