Collaborative Research: Physical properties and structure of silicate melts and supercooled liquids at high pressures

合作研究：高压硅酸盐熔体和过冷液体的物理性质和结构

• 批准号: 1214376
• 负责人: Yanbin Wang
• 金额: $ 12.36万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1214376&HistoricalAwards=false
• 关键词: Collaborative; Research; Physical; properties; structure

The thermal evolution and chemical differentiation of the Earth involves the segregation of silicate and metallic melts, and coexisting minerals due to differences in their density. This single factor impacts the initial condition as the Earth formed its hydrosphere and biosphere (to become a habitable planet), the efficiency of magmatic differentiation, evolution of volcanic systems and character of eruptions, formation of some economic ore deposits, transportation of volatiles through the deep mantle, and heat transfer across the core mantle boundary which, in turn, impacts generation of the magnetic field. The buoyancy relations between minerals and melts are strong functions of pressure caused by the greater compressibility of melts compared to minerals. Quantifying the response of increasing pressure on melt properties is challenging given the refractory nature, absence of long range structural order, and complex structural change that accommodates densification of melts. Critical measurements must be made under well-controlled laboratory conditions. The results of this research will greatly improve our understanding of dynamic processes within our planet and links to motions of the tectonic plates and global geochemical cycle.This research employs novel high-pressure experimental methods utilizing in situ X-ray techniques (microtomography, absorption and diffraction) and acoustic velocity measurements to determine the volumetric properties and structural changes in melts at deep Earth conditions. The results will help place tighter constraints on properties of the magma ocean, core formation, segregation and convection dynamics, and, ultimately, the thermal and chemical evolution of the Earth. These data will also contribute to our understanding of present-day dynamics involving the storage and transport of magma through the crust and mantle, spreading of tectonic plates from mid-ocean ridges, mantle plume upwelling, and possible reactions at the core-mantle boundary. Additionally, our efforts in connection with this project will help to further expand the opportunities for microtomography research at high pressures for the study of partial melting and deformation, among other phenomena at high pressures requiring detailed microstructure characterization in 3D. It is anticipated that the results of this work will have long-term benefits in the search and characterization of new exotic materials synthesized at high temperature and pressure for industrial applications.

地球的热演化和化学分异涉及硅酸盐和金属熔体的分离，以及由于密度差异而共存的矿物。 这一单一因素影响地球形成水圈和生物圈（成为宜居行星）时的初始条件、岩浆分异的效率、火山系统的演化和喷发的特征、一些经济矿床的形成、挥发物通过深部地幔的输送以及穿过地幔核心边界的传热，进而影响磁场的产生。 矿物和熔体之间的浮力关系是压力的强函数，这是由于熔体比矿物具有更大的可压缩性而引起的。 考虑到熔体的耐火特性、缺乏长程结构有序性以及适应熔体致密化的复杂结构变化，量化压力增加对熔体性能的响应具有挑战性。 关键测量必须在控制良好的实验室条件下进行。这项研究的结果将极大地提高我们对地球动态过程的理解，以及与构造板块运动和全球地球化学循环之间的联系。这项研究采用新颖的高压实验方法，利用原位 X 射线技术（显微断层扫描、吸收和衍射）和声速测量来确定地球深处熔体的体积特性和结构变化。 这些结果将有助于对岩浆海洋的特性、核心形成、分离和对流动力学，以及最终地球的热和化学演化施加更严格的限制。 这些数据还将有助于我们了解当今的动力学，包括岩浆通过地壳和地幔的储存和运输、构造板块从大洋中脊的扩张、地幔柱上涌以及地核-地幔边界可能发生的反应。 此外，我们与该项目相关的努力将有助于进一步扩大高压显微断层扫描研究的机会，以研究部分熔化和变形，以及其他需要 3D 详细微观结构表征的高压现象。 预计这项工作的结果将对在工业应用中高温高压下合成的新奇特材料的搜索和表征产生长期的好处。