Hydrous Defects and Diffusion in Mantle Minerals

在拟议的研究中，水溶解在几个地幔矿物（橄榄石，斜方辉石，镁橄榄石）的性质和扩散速率将进行调查，以及溶解水的化学动力学的影响。特别是，计划：1）扩展以前的工作，将橄榄石和镁橄榄石红外光谱中的O-H带与氢-本征缺陷缔合物相关联，并研究这些缔合物的扩散速率，以深入了解硅和镁缺陷物种的扩散速率; 2）表征斜方辉石中含水缺陷的性质，并研究氢-本征缺陷缔合物的掺入速率; 3）研究了镁橄榄石中的水化缺陷对铁镁互扩散的影响。这项研究扩展了PI在理解矿物中的微尺度缺陷与其整体行为之间的关系方面的贡献。鉴于目前对这一研究领域的大力重视，这一报告特别及时。这项工作的结果将提高我们对矿物缺陷的认识，以及溶解水在确定主要地幔矿物内部缺陷结构中的作用。这些调查还将扩大我们对地球内部的性质和动力学的理解，以及水在促进化学和机械过程中的作用，特别是晶内扩散和流变学。该研究计划将形成研究生博士研究的重点，研究生将在实验和分析工作中发挥主要作用，将在科学会议上展示研究成果，并将率先为科学期刊撰写关于个人研究主题的研究论文。

In the proposed research, the nature and rates of diffusion of water dissolved within several mantle minerals (olivine, orthopyroxene, and magnesiowustite) will be investigated as well as the effects of dissolved water on chemical kinetics. In particular, it is planned to: 1) extend previous work correlating O-H bands in the infrared spectra of olivine and forsterite with hydrogen-intrinsic defect associates and investigate the rates of diffusion of these associates to gain insight into diffusion rates for silicon and magnesium defect species; 2) characterize the nature of hydrous defects in orthopyroxene and investigate rates of incorporation of hydrogen-intrinsic defect associates; 3) investigate the effects of hydrous defects in magnesiowustite on the interdiffusion of iron and magnesium. This research extends on past contributions by the PI in understanding the relations between microscale defects in minerals and their bulk behavior. It is particularly timely given the strong current emphasis in this area of study. The results of this work will improve our knowledge of defects in minerals and the role of dissolved water in defining internal defect structure in the major mantle minerals. These investigations will also extend our understanding of the nature and dynamics of the Earth's interior and the role of water in facilitating chemical and mechanical processes, notably intracrystalline diffusion and rheology. This research program will form the focus of the PhD research of a graduate student, who will take the major role in the experimental and analytical work, will present the research at scientific conferences, and will take in the lead in writing research papers on the individual research topics for scientific journals.