CAREER: Evolutionary Processes in Crustal Seismic Anisotropy

职业：地壳地震各向异性的演化过程

• 批准号: 1252295
• 负责人: Kevin Mahan
• 金额: $ 49.78万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1252295&HistoricalAwards=false
• 关键词: CAREER; Evolutionary; Processes; Crustal; Seismic

Variation in seismic wave speed as a function of propagation direction, or seismic anisotropy, is an intrinsic property of rocks deformed at high temperature due to preferred mineral alignment and is readily detectable by methods that utilize natural seismic sources (e.g., earthquakes). With a remarkably growing array of techniques, seismic studies are using this phenomenon to detect new structural features in the Earth?s crust and mantle in all types of active and past tectonic settings, including subduction zones, arcs, collisional orogens, active transform faults, and large-scale extensional systems. However, confident interpretations of these features are hampered by the incomplete knowledge of the tectonic processes that govern the development and preservation of seismic anisotropy. This project is utilizing field- and laboratory-based analyses to explore three topical areas that impact the evolution of seismic anisotropy in crustal rocks: 1) prograde and retrograde chemical reactions (metamorphism), 2) the competing roles of different minerals, and 3) the influence of strain type, magnitude, and multiple deformation structures. The goal is to generate predictable relationships between deformation, metamorphism, and seismic anisotropy in crustal rocks that can be further tested by seismic observations and simulations. Such information will lead to increased understanding of seismic images which will allow a better understanding of crustal architecture and interpretation of tectonic processes. Seismic anisotropy is fundamentally a microstructural phenomenon best understood by crossing traditional boundaries between geology and physics. While graduate students will be involved during the academic year, the undergraduate component of the project during summers will focus on the University of Colorado?s Research Experiences in Solid Earth Sciences for Students (RESESS) program, the goal of which is to increase the number of students from underrepresented minority populations entering graduate school in the Earth sciences. The role of this project in the program is designed to positively impact both individual RESESS students and the group as a whole through 1) science mentoring, 2) an annual two-day Front Range multi-disciplinary field trip on Colorado geology, geomorphology, and geophysics for all RESESS interns, and 3) providing a summer fellowship for a graduate student to work with all the interns to provide feedback and to help develop their science presentation skills. The broader goal in this project is to expose graduate and undergraduate students to cross-disciplinary science models and multi-cultural research communities, in as many ways as possible, in order to better prepare these Earth scientists of the future for research challenges in the 21st century.

地震波速度的变化是传播方向或地震各向异性的函数，是由于首选矿物比对而在高温下变形的岩石的固有特性，并且可以通过利用自然地震源的方法（例如地震）来易于检测。随着一系列技术的不断增长，地震研究正在使用这种现象来检测地球上的新结构特征，并在所有类型的活性和过去的构造环境中，包括俯冲带，弧形，碰撞orogens，活性变换断层，，活跃的变换断层，，，，活性变换断层，弧形区域和过去的地壳中的新结构特征。和大规模的扩展系统。但是，对这些特征的自信解释受到了对控制地震各向异性发展和保存的构造过程的不完整知识的阻碍。该项目正在利用基于野外和实验室的分析来探索三个主题区域，这些区域影响地壳岩石中地震各向异性的演变：1）竞争作用和逆行化学反应（变质），2）不同矿物的竞争角色和3）应变类型，大小和多重变形结构的影响。目的是在地壳岩石中产生变形，变质和地震各向异性之间的可预测关系，这些关系可以通过地震观测和模拟进一步测试。此类信息将导致对地震图像的理解，这将使对地壳结构和对构造过程的解释有更好的了解。 地震各向异性从根本上是一种微观结构现象，最好通过跨越地质和物理学之间的传统界限来理解。虽然研究生将在学年参与其中，但夏季，该项目的本科生将重点介绍科罗拉多大学的学生固体地球科学研究经验（Resess）计划，其目的是增加数量来自代表性不足的少数民族的学生进入地球科学研究生院。该项目在该计划中的作用旨在积极影响单个经验学生和整个小组的整体至1）科学指导，2）每年为期两天的前范围，在科罗拉多地质学，地貌学和地质学和所有经验实习生的地球物理学，以及3）为研究生提供与所有实习生一起提供反馈并帮助发展其科学演示技巧的夏季奖学金。该项目的更广泛的目标是使毕业生和本科生以尽可能多的方式揭露跨学科科学模型和多元文化研究社区世纪。

项目成果

Confronting Solid‐State Shear Bias: Magmatic Fabric Contribution to Crustal Seismic Anisotropy

面对固态剪切偏差：岩浆组构对地壳地震各向异性的贡献

• DOI: 10.1029/2022gl102399
• 发表时间: 2023
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Frothingham, Michael G.;Mahan, Kevin H.;Schulte‐Pelkum, Vera;Goncalves, Philippe;Zucali, Michele
• 通讯作者: Zucali, Michele