CAREER: Upper mantle anisotropy: the effect of pressure, temperature and hydration

职业：上地幔各向异性：压力、温度和水合作用的影响

• 批准号: 1847707
• 负责人: Jin Zhang
• 金额: $ 63.33万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1847707&HistoricalAwards=false
• 关键词: CAREER; Upper; mantle; anisotropy; effect

Thermal convection in the Earth's mantle drives plate tectonics which generates natural hazards, such as volcanic eruptions and earthquakes. Understanding mantle flows has, thus, strong societal relevance. Seismology is a major tool when investigating mantle flows. Differences in seismic velocities, called seismic anisotropy, reflect the elastic anisotropy of mantle rocks. This anisotropy results from the properties of their constitutive minerals and from their deformation by convective flows. Here, the PI will experimentally measure the elastic anisotropy of various mantle minerals at the extreme pressures and temperatures prevailing in the Earth. From the data, rock seismic anisotropies can be calculated and compared with field observations. The experiments will be carried out at a national synchrotron facility, where powerful X-rays are generated, and in the PI's laser laboratory at University of New Mexico (UNM). The lasers and X-rays will be guided toward small mineral specimens pressurized in-between two diamonds. Mineral elastic properties can be extracted by quantifying the interaction between X-ray/laser beams and specimens which induces elastic waves in the minerals. Results from this project will improve the understanding of three critical zones in the Earth's mantle, located near plate boundaries and within the first few hundred kilometers underneath the surface. The project outcomes will be integrated into educational outreaches towards high-school students in Albuquerque (NM), notably from under-represented groups, as well as in a new introductory course at UNM. The project will also support two early-career scientists and provide training to one graduate student at UNM.This proposal aims at better understanding the seismic anisotropy observed in three critical regions of the Earth's upper mantle: the lithosphere-asthenosphere boundary, the mid-lithosphere discontinuity and the mantle wedge in subduction zones. The goal is to link the anisotropy to the elastic properties of the relevant minerals. The PI will perform experiments in the diamond-anvil cell at the high pressures and temperatures prevailing in the mantle. Single-crystal Brillouin spectroscopy at PI's laser spectroscopy laboratory and a national synchrotron facility, the Advance Photon Source (IL), will allow measuring the elastic constants of hydrogen-bearing olivine and pyroxenes and minerals from the amphibole and serpentine groups. Specimens will be prepared by focused ion beam and a novel scattering geometry will be implemented to ensure the success of the project. The research outcomes will be integrated into educational and outreach activities. The PI, an early-career female scientist, will work with teachers from Albuquerque high schools to encourage students to pursue STEM studies. A new introductory geoscience course will provide fun movie-discussion-exploration style learning experiences at University of New Mexico. The objective is to engage at an early stage more female and students from underrepresented groups into Earth Sciences careers. The project will also support a postdoctoral associate and provide training to one graduate student at UNM.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球地幔中的热对流驱动板块构造产生自然危害，例如火山喷发和地震。因此，了解地幔流具有强大的社会意义。地震学是研究地幔流时的主要工具。地震速度的差异称为地震各向异性，反映了地幔岩石的弹性各向异性。这种各向异性是由于其本构矿物质的特性以及对流流的变形。在这里，PI将通过实验测量地球上极端压力和温度下各种地幔矿物的弹性各向异性。从数据中，可以计算岩石地震各向异性，并将其与现场观测值进行比较。该实验将在国家同步器设施中进行，在该设施中产生强大的X射线，并在新墨西哥大学（UNM）的PI激光实验室中进行。激光和X射线将被引导到两颗钻石之间的小矿物标本。可以通过量化X射线/激光束和样品之间的相互作用来提取矿物弹性性能，从而诱导矿物质中的弹性波。该项目的结果将提高对地球地幔中三个关键区域的理解，位于板边界附近，在表面下方的前几百公里内。该项目的成果将纳入对阿尔伯克基（NM）的高中生的教育宣传，尤其是来自代表性不足的团体以及UNM的新入门课程。该项目还将支持两名早期职业科学家，并向UNM的一名研究生提供培训。该提案旨在更好地理解地球上层地幔的三个关键区域中观察到的地震各向异性：岩石圈 - 心理圈边界，中层中的不连续性和中产阶级的楔形zone zone zone zone zone zone。目的是将各向异性与相关矿物质的弹性特性联系起来。 PI将在高压和地幔中普遍存在的高压和温度下在钻石 - 洋维池中进行实验。 PI激光光谱实验室和国家同步器设备（Advance Photon Source（IL））的单晶布里杆菌光谱法将允许测量来自两栖动物和蛇形基团的含氢橄榄石和去角质和矿物质的弹性常数。标本将由聚焦的离子束制备，并将实现新颖的散射几何形状，以确保项目的成功。研究成果将纳入教育和外展活动。 PI是一位早期的女性科学家，将与阿尔伯克基高中的老师合作，​​鼓励学生从事STEM研究。新的介绍性地球科学课程将在新墨西哥大学提供有趣的电影讨论风格的学习体验。目的是在早期阶段参与更多的女性和来自代表性不足的群体的学生从事地球科学职业。该项目还将支持博士后同事，并为UNM的一名研究生提供培训。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估标准通过评估来支持的。

项目成果

Effect of structural water on the elasticity of orthopyroxene

• DOI: 10.2138/am-2021-7843
• 发表时间: 2022-03
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: M. Hou;Wencai Zhou;M. Hao;Florian Tian-Siang Hua;J. Kung;Dongzhou Zhang;P. Dera;Jin S. Zhang

The Water-Fe-Pressure dependent single-crystal elastic properties of wadsleyite: Implications for the seismic anisotropy in the upper Mantle Transition Zone

瓦兹利石的水-铁-压力依赖性单晶弹性特性：对上地幔过渡带地震各向异性的影响

• DOI: 10.1016/j.epsl.2021.116955
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Zhou, Wen-Yi;Ren, Zhiyuan;Zhang, Jin S.;Chen, Bin;Hao, Ming;Ohuchi, Tomohiro;Miyagi, Lowell;Zhang, Dongzhou;Alp, Esen E.;Lavina, Barbara
• 通讯作者: Lavina, Barbara