Structure/property Relations in Silicate-C-O-H-N Melts Melts and Fluids Characterized Experimentally, In-situ, at Mantle Redox Conditions, Pressure, and Temperature

智力上的优点。S提出了一项实验研究，以促进我们对地球内部C-O-H-N系统中挥发性组分的预算和回收过程的理解。当样品主要在温度、压力和氧化还原条件下使用热液金刚石顶压室(HDAC)时，将研究硅酸盐熔体和C-O-H-N流体、流体/熔体元素和稳定同位素分馏的结构和输运、体积和热力学性质之间的关系。主要目标是：[1]使用振动光谱表征硅酸盐-C-O-H-N熔体、矿物和流体系统的结构和性质，以此来模拟天然岩浆系统中流体和熔体的行为。[2]使用振动光谱和淬火材料的微束分析，确定硅酸盐-科恩系统中矿物、熔体和流体之间的结构物种和同位素的分馏。[3]发展结构-性质模型来解释与地球上地幔相对应的P-T条件下天然岩浆系统的行为。目前对C-O-H-N挥发性组分在硅酸盐熔体中的溶解结构和溶解机理的认识主要基于对淬火熔体(玻璃)的分析和结构检验。然而，这些信息并不能准确地反映实际熔体的性质。相反，拟议中的实验将使样品能够在代表地球上地幔S的温度、压力和氧化还原条件下进行测量。熔体结构如何影响矿物/熔体元素分配的表征将通过将熔体结构数据与微量元素分配实验(依赖于运行产品的电子探针和离子探针分析)相结合来解决。结构物种在熔体和流体之间的分配将通过振动光谱技术完成，并将与元素分析进行比较，作为校准振动光谱确定的结构物种分配的一种手段。还将开发用于在所需的压力、温度和氧化还原条件下使用振动光谱来确定流体和熔体之间的D/H分馏的方案。拟议的工作还将提供有关深部地壳和上地幔条件下岩浆系统(熔体和流体)组分混合的流变学、压缩性和热力学方面的新信息。更广泛的影响。PI通常有一个高中生和一个本科生(由地球物理实验室资助)在他的实验室工作。这将继续作为拟议研究的一部分。这些计划非常成功，例如，在同行评议文献中发表了七篇文章，这些文章来自过去几年在PIS实验室所做的工作，本科生和高中生是共同作者。在这方面，PI贡献了时间来评判和监督初中生的项目。本次博览会的获胜者将参加国家科学竞赛，如国际科学博览会和西门子基金会的数学-科学-技术竞赛。

Intellectual merits. An experimental study is proposed to advance our understanding the processes that govern the budget and recycling of volatile components in the system C-O-H-N in the Earth?s interior. Relationships between structure and transport, volume, and thermodynamic properties of silicate melts and C-O-H-N fluid and fluid/melt element and stable isotope fractionation will be examined while samples are at temperature, pressure, and redox conditions primarily using a hydrothermal diamond anvil cell (HDAC). Major objectives are to: [1] Use vibrational spectroscopy to characterize structure and properties in silicate-C-O-H-N melt, mineral, and fluid systems as proxies to model the behavior of fluids and melts in natural magmatic systems. [2] Determine fractionation of structural species, and of isotopes between minerals, melts, and fluids in silicate-COHN systems using vibrational spectroscopy and microbeam analyses of quenched materials. [3] Develop structure-property models to explain the behavior of natural magmatic systems at P-T conditions corresponding to the upper mantle of the Earth. Current knowledge of structure of solubility and solution mechanisms of C-O-H-N volatile components in silicate melts is based largely on analytical and structural examination of quenched melts (glasses). However, this information does not precisely reflect properties of actual melts. Conversely, the proposed experiments will enable measurements of samples while they are being held at temperature, pressure and redox conditions representative of the Earth?s upper mantle. Characterization how melt structure affects mineral/melt element partitioning will be addressed by combining melt structural data with trace element partitioning experiments (relying on electron microprobe and ion probe analysis of run products). Partitioning of structural species between melts and fluids will be accomplished with vibrational spectroscopic techniques and will be compared with elemental analyses as a means to calibrate the partitioning of the structural species determined by vibrational spectroscopy. Protocols will also be developed for use of vibrational spectroscopy to determine D/H fractionation between fluid and melt while at desired pressure, temperature, and redox conditions. The proposed work will also provide new information on rheology, compressibility, and thermodynamics of component mixing for magmatic systems (melts and fluids) at deep crust and upper mantle conditions. Broader Impacts. The PI typically has one high school student and one undergraduate student (funded by the Geophysical Laboratory) working in his laboratory. This will continue as a part of the proposed research. These programs have been very successful resulting, for example, in seven articles in the peer reviewed literature from the work done in the PIs laboratories during the last several years with undergraduate and high school students as co-authors. In this regard, the PI contributes time to judge and supervise projects by middle and high school students. Winners of this fair proceed to national science competitions such as the International Science Fair and the Siemens Foundation's competition in Math-Science-Technology.