Experimental Constraints on Physical Mechanisms of Core Formation

了解导致行星早期分化为岩石(硅酸盐)地幔和金属核的化学和物理过程，是理解地球演化的基础。有人提出，早期地球经历了广泛的熔融，由此产生的金属液体在高压和温度下从剩余的硅酸盐物质中分离出来，形成了核心。部分熔融的硅酸盐在颗粒尺度上的核心形成机制的综合框架尚未完全建立。该项目利用最近开发的实验方法和成像技术，结合数值模拟来确定在与地球分异相关的条件下，允许金属液体从部分熔融的硅酸盐中分离的物理过程。这项工作将研究在颗粒尺度上几种平衡和非平衡核形成情景下的金属分凝速率(S)。具体来说，将量化部分熔融的硅酸盐熔体、不同成分的金属熔体的不同程度的影响以及持续变形对金属熔体的分布和流动性的影响。实验测量和数值模拟相结合的方法增加了一种新的方法来量化成核熔体的三维几何和粒度迁移率，这是传统的渗透率和运移速度估计所不能实现的。

Understanding both the chemical and physical processes that contribute to the early differentiation of planets into rocky (silicate) mantles and metallic cores is fundamental to the understanding of Earth's evolution. It has been proposed that the early Earth experienced wide spread melting, and the resulting metallic liquid segregated from the remaining silicate material at high pressures and temperatures forming the core. A comprehensive framework for core formation mechanisms in a partially molten silicate at the grain scale has not yet been fully established. This project utilizes recently developed experimental methods and imaging techniques coupled with numerical simulations to determine the physical processes that allow for segregation of metallic liquids from partially molten silicates at conditions relevant to the differentiation of the planet Earth.This work will address the rate(s) of metal segregation for several equilibrium and non-equilibrium core formation scenarios at the grain scale. Specifically, the effect varying degrees of partially molten silicate melt, different compositions of metallic melt and the influence of sustained deformation on the distribution and mobility of metallic melts will be quantified. The combined approach of experimental measurement and numerical simulation adds a new way of quantifying the three dimensional geometry and grain scale mobility of core forming melts that has not been available through traditional estimates of permeability and migration velocity.