X-ray and Spectroscopic Studies of Subduction-Related Phases: Probing the Mid-Point of Volatile Recycling in the Earth

俯冲相关相的 X 射线和光谱研究：探测地球挥发性物质循环的中点

• 批准号: 1620423
• 负责人: Quentin Williams
• 金额: $ 37万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1620423&HistoricalAwards=false
• 关键词: ray; Spectroscopic; Studies; Subduction; Related; ray; Spectroscopic; Studies; Subduction; Related

How the major materials of our hydrosphere and atmosphere, such as water and carbon dioxide, are cycled into the deep Earth within solid mineral phases via plate tectonics, and then ultimately released as fluid phases at high pressures and temperatures, is of key importance for how subduction-associated volcanism (like the circum-Pacific "Ring of Fire") is produced, and also possibly for the occurrence of deep earthquakes (at depths greater than ~200 km). In this project, the investigators plan to examine water- and carbon-containing minerals of relevance under the high-pressure and high temperature conditions under which they release water and carbon dioxide to determine: (1) their properties that govern when water or carbon dioxide are released at depth; and (2) whether water or carbon dioxide are released gradually or abruptly. These results will constrain how the water that ultimately generates circum-Pacific volcanism via water-induced melting is released at depth in the planet, and help in the modeling of magma production at depth; and will explore how carbon dioxide is released at depth and the form in which it might be transported to the surface. Thus, these results have fundamental relevance for the production of volcanism at continental margins, and for how deep subduction-related earthquakes (which are likely greased by fluids) are generated. In conducting these experiments, the group will spearhead the development of a new facility, which will be available to the scientific community as a whole, which is designed to conduct high-pressure/high-temperature characterizations of materials at the Advanced Light Source at Lawrence Berkeley National Labs. The group extensively engages undergraduates in its research effort, and the graduate students supported by this grant include a military veteran. The results are also incorporated into undergraduate curricula at the PI's institution.The investigator team plans to: (1) examine the properties of important carriers of volatiles into Earth's mantle at simultaneous high pressures and high temperatures using high precision single-crystal x-ray diffraction; and (2) characterize the properties of carbonates of relevance to carbonatite petrogenesis at high pressures using infrared and Raman spectroscopy. In tandem with the first objective, the establishment of a new, community-accessible, high-pressure/high-temperature synchrotron-based single crystal x-ray diffraction facility will be facilitated by this support. The cycling of water and carbon dioxide into and out of Earth's interior are pivotal processes that impact both the properties of the solid Earth (through their effects on melting and rheology) and Earth's surface (through the volume of the hydrosphere and the composition of Earth's atmosphere). The team proposes to probe the properties of volatile-bearing phases under subduction conditions to gain insights into: (1) the polymorphism of volatile-bearing phases in Earth's mantle (or, what is degassing at depth); (2) the structures of volatile-bearing phases at high-pressures and temperatures (to examine why these phases hold volatiles); and (3) how phases that are known to carry water to depth (and particularly lawsonite and phengitic micas) behave as they approach (and hopefully exceed) their dehydration conditions. They also will provide new constraints on the rich polymorphism of phases associated with the binding of the carbonate ion under mantle conditions: the focus here will be on alkali-rich carbonates, which have recently been demonstrated to be associated with deep carbonatite melting, and which have largely been uninterrogated at high pressure conditions. The team will utilize this project to deploy two graduate students to assist, work through, shake down and debug a new, world-class high-pressure single-crystal x-ray diffraction set-up that will be set-up and commissioned over the next year at the Advanced Light Source (ALS) at Lawrence Berkeley National Labs (LBNL). This facility will be available to the community as a whole through the General User Program proposal process of the ALS (the facility will also be part of the COMPRES-Consortium's Approved Program at the ALS, and thus will have assistance for users who are awarded time). In addition to this deployment of new community infrastructure, the PI will: (1) contribute to the education of a diverse group of graduate students (currently, one military veteran, one returning female) and undergraduates; (2) continue to publish/contribute to the literature on topics of broad interest for those interested in the natural history of the planet (and promote these as appropriate with press releases); and (3) incorporate new results into UCSC undergraduate teaching (typically, to ~90 earth sciences majors per year).

我们水层和大气的主要材料如何通过板块构造循环到固体矿物相内的深地球中，然后最终以高压力和温度下的流体相位释放，对于更大的象征性的火山剂（以及探索了圆形的火环）是如何更重要的，并且是对地球的更大程度的重要性，并且是对绕线的影响，并且是对圆形的探针（也可能是对圆形的燃料，也是如此的“发射环”，并且是对地球的影响。超过200公里）。在该项目中，研究人员计划在高压和高温条件下检查含水和碳相关性的矿物质，在这些矿物下释放水和二氧化碳，以确定：（1）其在深度释放水或二氧化碳何时释放的特性； （2）水还是二氧化碳是逐渐或突然释放的。这些结果将限制最终通过水引起的熔化产生范围的火山的水如何在地球上释放，并有助于深度建模岩浆产量。并将探讨如何以深度释放二氧化碳以及将其转运到表面的形式。因此，这些结果与在大陆边缘的火山产生以及与俯冲相关的地震（可能是流体润滑剂）如何产生的基本相关性。在进行这些实验时，该小组将率先开发了一个新设施，该设施将为整个科学界使用，该设施旨在在劳伦斯·伯克利国家实验室的高级光源对材料的高压/高温特征进行高压/高温特征。该小组广泛地参与了本科生的研究工作，该赠款支持的研究生包括一名退伍军人。结果还将结果纳入PI机构的本科课程中。研究人员团队计划：（1）使用高精度单晶体X射线X射线衍射，研究挥发物的重要载体在地球的地幔中的特性； （2）使用红外和拉曼光谱法在高压下在高压下与碳酸石岩石相关的碳酸盐特性。与第一个目标同时，该支持将促进建立一种新的，社区访问，高压/高温同步加速器的单晶X射线衍射设施的新型，高压/高温同步器。 水和二氧化碳进入地球内部的循环是关键过程，它们既影响固体地球的特性（通过它们对融化和流变学的影响）和地球表面（通过水圈的体积和地球大气的组成）。该小组建议在俯冲条件下探测挥发性相的性质，以获取以下深刻的见解：（1）地球地幔中挥发性相的多态性（或深度的脱气）； （2）在高压和温度下，挥发性相的结构（要检查为什么这些阶段保持挥发物）； （3）当他们接近（并希望超过）脱水条件时，已知将水深度（尤其是Lawsonite和Phengitic云母）延伸到深度的相位。 他们还将对与碳酸盐离子在地幔条件下的结合相关的丰富阶段的多态性提供新的限制：这里的重点将放在富含碱的碳酸盐上，这些碳酸盐最近已被证明与深碳酸盐熔化有关，并且在高压力条件下在很大程度上未被忽视。该团队将利用该项目部署两名研究生来协助，努力，摇晃和调试一个新的，世界一流的高压单晶X射线衍射设置，该设置将在明年的劳伦斯·伯克利国家实验室（Lawrence Berkeley National Labs）（LBNL）设置和委托在明年的高级光源（ALS）。该设施将通过ALS的一般用户计划提案流程提供给社区的整体（该设施还将成为ALS批准的批准计划的一部分，因此将为获得时间的用户提供帮助）。除了部署新的社区基础设施外，PI还将：（1）为一群多样化的研究生（目前是一名退伍军人，一名返回的女性）和本科生的教育做出贡献； （2）继续发布/贡献有关对地球自然历史感兴趣的人的广泛兴趣主题的文献（并根据新闻稿适当推广这些话题）； （3）将新结果纳入UCSC本科教学（通常为每年约90个地球科学专业）。