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

基本信息

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

项目摘要

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.

原子沿着矿物颗粒之间的边界传输是一个基本但知之甚少的过程，它在许多重要的地质现象中发挥着重要作用，从地震产生的地震能量的衰减到与地幔对流和板块相关的许多变形和化学传输过程构造学。该项目支持对 MgO（地球深部地幔的主要成分）中的晶界扩散进行综合理论和实验研究。这项研究的结果将提高估计晶界化学迁移率以及地球深处相关地球物理和地球化学性质的能力。该实验和理论研究相结合的项目将专门针对晶界扩散所涉及的原子级机制，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、压力以及钙和硅存在的依赖性将通过扩散偶实验、第一原理和经典分子动力学模拟来确定。理论模拟将提供有关扩散机制、晶界输运与晶界结构的关系以及晶界扩散数据外推至与地球最深地幔相关的高压的关键信息。