CAREER: Deformation and Anisotropy Development in the Lower-most Mantle

事业：最下地幔的变形和各向异性发展

• 批准号: 1654687
• 负责人: Lowell Miyagi
• 金额: $ 57万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1654687&HistoricalAwards=false
• 关键词: CAREER; Deformation; Anisotropy; Development; Lower

Mantle convection is the internal engine which drives dynamic processes such as earthquakes and volcanism. Since there is no direct way to image mantle flow, our knowledge about this process is limited. This project will improve our ability to link seismic observations to deformation structure and flow geometry in the deep Earth. In particular it will provide experimental data on the strength on rocks and minerals at the base of the mantle and will determine the microscopic mechanisms that lead to flow alignment of minerals in the deep earth. Understanding the dynamic processes at the base of the mantle will provide new insight into the mechanics and geometry of mantle convection. High pressure and temperature deformation experiments performed during this project will also advance our understanding of the mechanical behavior of composite materials subjected to extreme pressure and temperature conditions. In addition to basic science advances the outreach component of this project will improve undergraduate recruitment into geosciences through early exposure in secondary schools. It will directly benefit the quality of secondary school education in Utah by providing mentoring and authentic research experience to secondary school teachers through the Masters of Science for Secondary School Teachers (MSSST) Program at the University of Utah. In addition, through collaboration with MSSST teachers, the PI will develop geophysics teaching modules to be incorporated into secondary school earth science, physics, and chemistry courses. This project will also provide support and training for a graduate student and a postdoctoral researcher. The D" region, which lies just above the core mantle boundary (~2700-2900 km), plays a critical role in mantle convection. Understanding the dynamic processes occurring in the D" will advance our understanding of mantle convection. Seismic anisotropy is observed in much of the D" and is widely attributed to crystal preferred orientation (texture) of minerals that results from ductile deformation during mantle convection. If the relationship between deformation, texture, and anisotropy are understood, anisotropy can be used to map mantle flow. Most interpretations of D" anisotropy in terms of mantle flow are based on texture studies related only to deformation and in the context of single phase experiments. However, high pressure diamond anvil cell experiments on lower mantle phases have documented a range textures that develop due to phase transformations. Additionally the few texture measurements that exist for deformation of multi-phase lower mantle assemblages (rocks) suggest complex interactions between the phases. This project will use the diamond anvil cell and synchrotron radial diffraction to study orientation relationships and texture inheritance during bridgmanite and post-perovskite phase transitions and will investigate the effects of poly-phase deformation on texture development in lower mantle mineral phases. By understanding these processes, this proposal will enhance our ability to interpret seismic anisotropy in terms of phase transformations and mantle flow.

地幔对流是驱动地震和火山活动等动力过程的内部引擎。由于没有直接的方法来成像地幔流，我们对这个过程的知识是有限的。 该项目将提高我们将地震观测与地球深部变形结构和流动几何学联系起来的能力。 特别是，它将提供关于地幔底部岩石和矿物强度的实验数据，并将确定导致地球深部矿物流动排列的微观机制。了解地幔底部的动力学过程将为地幔对流的力学和几何学提供新的见解。 在该项目中进行的高压和高温变形实验也将促进我们对复合材料在极端压力和温度条件下的力学行为的理解。 除了基础科学的进步外，该项目的推广部分将通过在中学的早期接触改善本科生对地球科学的招聘。 它将通过犹他州大学的中学教师科学硕士（MSSST）项目为中学教师提供指导和真实的研究经验，直接有利于犹他州中学教育的质量。 此外，通过与MSSST教师合作，PI将开发地球物理学教学模块，将其纳入中学地球科学，物理和化学课程。该项目还将为一名研究生和一名博士后研究员提供支持和培训。 位于核幔边界上方的D”区（~2700-2900 km）在地幔对流中起着关键作用。 了解D”中发生的动力学过程将促进我们对地幔对流的理解。 地震各向异性在D”的大部分被观察到，并被广泛归因于矿物的晶体择优取向（纹理），这是地幔对流过程中的韧性变形造成的。如果了解了变形、结构和各向异性之间的关系，就可以用各向异性来绘制地幔流图。 大多数关于地幔流的D”各向异性的解释都是基于仅与形变有关的结构研究和单相实验。 然而，高压金刚石对顶砧实验下地幔阶段已经记录了一系列的纹理，发展由于相变。 此外，存在于多相下地幔组合（岩石）的变形的几个纹理测量表明相之间的复杂的相互作用。该项目将使用金刚石对顶砧和同步辐射径向衍射来研究硼镁石和后钙钛矿相变过程中的取向关系和织构遗传，并将研究多相变形对下地幔矿物相织构发展的影响。通过理解这些过程，这一建议将提高我们解释地震各向异性的相变和地幔流方面的能力。

项目成果

Deformation of ZrSiO4 -MgO aggregates: Deviatoric stress as a control on deformation mechanisms

ZrSiO4 -MgO 聚集体的变形：偏应力作为变形机制的控制

• DOI: 10.1103/physrevb.105.l220101
• 发表时间: 2022
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Zhou, Xiaoling;Chen, Lianyang;Yuan, Mingzhi;Lin, Feng;Ye, Tian;Zhao, Feng;Kunz, Martin;Miyagi, Lowell
• 通讯作者: Miyagi, Lowell

Yield strength of CeO2 measured from static compression in a radial diamond anvil cell

• DOI: 10.1063/5.0097975
• 发表时间: 2022-09-21
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Huston，Larissa Q.;Couper，Samantha C.;Sturtevant，Blake T.
• 通讯作者: Sturtevant，Blake T.

High-pressure strengthening in ultrafine-grained metals

• DOI: 10.1038/s41586-020-2036-z
• 发表时间: 2020-02
• 期刊: Nature
• 影响因子: 64.8
• 作者: Xiaoling Zhou;Z. Feng;Linli Zhu;Jianing Xu;L. Miyagi;Hongliang Dong;H. Sheng;Yanju Wang

Elasto-viscoplastic self consistent modeling of the ambient temperature plastic behavior of periclase deformed up to 5.4 GPa

对变形高达 5.4 GPa 的方镁石的环境温度塑性行为进行弹粘塑性自洽建模

• DOI: 10.1063/1.4999951
• 发表时间: 2017
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: Lin, F.;Hilairet, N.;Raterron, P.;Addad, A.;Immoor, J.;Marquardt, H.;Tomé, C. N.;Miyagi, L.;Merkel, S.
• 通讯作者: Merkel, S.

Machine Learning Directed Search for Ultraincompressible, Superhard Materials

• DOI: 10.1021/jacs.8b02717
• 发表时间: 2018-08-08
• 期刊: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
• 影响因子: 15
• 作者: Tehrani, Aria Mansouri;Oliynyk, Anton O.;Brgoch, Jakoah
• 通讯作者: Brgoch, Jakoah