CSEDI: Collaborative Experimental and Fluid-Dynamical Study on Core Formation of the Earth

这个项目是一个合作的努力，以研究地核的起源及其与行星吸积的时间和机制的关系。这项工作结合了实验和理论工作，并依赖于金刚石细胞高压-高温化学研究的新概念、多相流动和行星演化的流体动力学建模，以及结合实验参数和流体动力学建模的地球化学建模，以建立撞击引起的岩浆海洋的岩心形成和演化模型的置信限。实验程序将确定在亲石-亲铁边界附近的一组关键元素的分配，以及在重要的放射性衰变系统中涉及的某些高度亲铁元素。地幔中这两种元素的地球化学特征提供了地核形成的记录，因为这一过程有效地从地幔中提取了亲铁元素。萃取过程的温度、压力和时间尺度是实验、理论和地球化学发现的未知参数。在高压实验中，我们将利用富含W、Re和Os的铁合金作为内部金属加热器嵌入到液态硅酸盐系统中，研究液态硅酸盐和金属之间Hf和W以及Re和Os的分配。起始材料中不同的体积铁含量为硅酸盐-金属体系提供了一组铁归一化分配系数（kd值），然后可以从实际的实验氧化还原条件（接近各自的金属氧化物缓冲层）推断出地核形成的更还原条件，并从高度富集的实验金属-硅酸盐体系推断出所检测元素的自然丰度。随着这项实验的努力，这些研究人员将首次开始将理解流体混合物乳化的基本进展纳入冲击吸积和行星分化过程的流体动力学建模方法中。

This project is a collaborative effort to study the origin of Earth's core and its relationship to the timing and mechanism of planetary accretion. This effort combines experimental and theoretical work and relies on a novel concept of high pressure-temperature chemical studies in diamond cells, on fluid dynamic modeling of multiphase flows and planetary evolution, and on geochemical modeling combining parameters from the experiments and the fluid-dynamic modeling to establish confidence limits on models of core-formation and evolution of an impact-induced magma-ocean. The experimental program will determine the partitioning of a set of key elements near the lithophile-siderophile boundary and certain highly siderophile elements that are involved in important radioactive decay systems. Geochemical signatures of both types of elements in the Earth's mantle provide the record of core-formation, because this process efficiently extracted siderophile elements out of the mantle. Temperature, pressure, and time-scale of this extraction processes are the unknown parameters the proposed combination of experimental, theoretical, and geochemical findings shall constrain. The proposed experiments will focus on partitioning of Hf and W and of Re and Os between liquid silicate and metal using W-, Re-, and Os-rich iron-alloys as internal metal heaters embedded in liquid silicate systems in high-pressure experiments. Varying bulk Fe content in the starting materials provides sets of Fe-normalized partition coefficients (kD-values) for the silicate-metal system which then can be extrapolated from the actual experimental redox conditions (close to the respective metal-oxide buffers) to the more reducing conditions of Earth's core formation and from the highly enriched experimental metal-silicate systems to natural abundances of the examined elements. Along with this experimental effort these researchers will start to incorporate for the first time fundamental advances in understanding emulsification of fluid mixtures into methods of fluid dynamic modeling of impact accretion and planetary differentiation processes.