Grain Boundary Diffusion in the Mantle: An Integrated Theoretical and Experimental Study of MgO

地幔中的晶界扩散：MgO 的理论与实验综合研究

• 批准号: 1250331
• 负责人: James Van Orman
• 金额: $ 32万
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1250331&HistoricalAwards=false
• 关键词: Grain; Boundary; Diffusion; Mantle; Integrated

Transport of atoms along the boundaries between mineral grains is a fundamental but poorly understood process that plays an important role in many important geological phenomena, from the attenuation of seismic energy produced by earthquakes to the many deformation and chemical transport processes associated with mantle convection and plate tectonics. This project supports a combined theoretical and experimental study of grain boundary diffusion in MgO, a major component of Earth's deep mantle. The results of this study will improve the ability to estimate grain boundary chemical transport rates and related geophysical and geochemical properties of the deep Earth. The combined experimental and theoretical research program will specifically target the atomic-level mechanisms involved in grain boundary diffusion, and the influence of pressure, chemical impurities and grain boundary structure on element mobility. Grain boundary diffusion coefficients, and their dependence on temperature, pressure and the presence of calcium and silicon, will be determined using diffusion couple experiments, and first-principles and classical molecular dynamics simulations. The theoretical simulations will provide critical information on the diffusion mechanism(s), the relation of grain boundary transport to grain boundary structure, and the extrapolation of grain boundary diffusion data to the high pressures relevant to Earth?s deepest mantle.

原子沿矿物颗粒之间的边界的运输是一个基本但知之甚少的过程，在许多重要的地质现象中起着重要作用，从地震产生的地震能量的衰减到与地幔对流和板块构造相关的许多变形和化学传输过程。该项目支持MGO中晶界扩散的理论和实验研究，MGO是地球深地幔的主要组成部分。 这项研究的结果将提高估计深层地球的晶界化学转运率以及相关地球物理和地球化学特性的能力。 合并的实验和理论研究计划将特别针对涉及晶界扩散的原子级机制，以及压力，化学杂质和晶界结构对元素迁移率的影响。晶界扩散系数及其对温度，压力和钙和硅的依赖性将使用扩散夫妇实验以及第一原理和经典分子动力学模拟确定。 理论模拟将提供有关扩散机理，晶界传输到晶界结构的关系以及晶界扩散数据的推断到与地球最深地幔相关的高压的关键信息。