Experimental Constraints on Physical Mechanisms of Core Formation

岩心形成物理机制的实验约束

• 批准号: 1322022
• 负责人: Heather Watson
• 金额: $ 17.86万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1322022&HistoricalAwards=false
• 关键词: Experimental; Constraints; Physical; Mechanisms; Core

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.

了解导致行星早期分化为岩石（硅酸盐）地幔和金属内核的化学和物理过程，是理解地球演化的基础。有人提出，早期地球经历了大范围的熔融，在高压和高温下，金属液体从剩余的硅酸盐物质中分离出来，形成了地核。在颗粒尺度上部分熔融硅酸盐中岩心形成机制的全面框架尚未完全建立。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化相关的条件下，允许金属液体从部分熔融硅酸盐中分离出来的物理过程。这项工作将在晶粒尺度上解决几种平衡和非平衡岩心形成情况下金属偏析的速率。具体而言，将量化不同程度的部分熔融硅酸盐熔体、不同成分的金属熔体以及持续变形对金属熔体分布和迁移率的影响。实验测量与数值模拟相结合的方法为量化岩心成形熔体的三维几何形状和晶粒迁移率提供了一种新的方法，这是传统的渗透率和迁移速度估计所无法实现的。