CAREER: Evolutionary Processes in Crustal Seismic Anisotropy

作为传播方向或地震各向异性的函数的地震波速度的变化是由于优选的矿物排列而在高温下变形的岩石的固有性质，并且通过利用天然地震源（例如，地震）。随着一系列技术的显著增长，地震研究正在利用这种现象来探测地球中新的结构特征。研究了各种活动和过去构造环境中的地壳和地幔，包括俯冲带、岛弧、碰撞造山带、活动转换断层和大规模伸展系统。然而，由于对控制地震各向异性的发展和保存的构造过程的不完全了解，对这些特征的可靠解释受到阻碍。该项目利用基于现场和实验室的分析来探索影响地壳岩石中地震各向异性演化的三个主题领域：1）逆冲和逆冲化学反应（变质作用），2）不同矿物的竞争作用，以及3）应变类型，幅度和多重变形结构的影响。目标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行进一步测试。这些信息将导致对地震图像的更多了解，从而能够更好地了解地壳结构和解释构造过程。 地震各向异性从根本上说是一种微观结构现象，最好通过跨越地质学和物理学之间的传统界限来理解。虽然研究生将在学年期间参与，但该项目的本科部分在夏季将集中在科罗拉多大学？该计划的目标是增加来自代表性不足的少数民族人口的学生进入地球科学研究生院的人数。该项目在该计划中的作用旨在通过1）科学指导，2）每年为期两天的科罗拉多地质学，地貌学和地球物理学的前沿范围多学科实地考察，为所有RESESS实习生，以及3）为研究生提供暑期奖学金，与所有实习生一起提供反馈，并帮助培养他们的科学演讲技能。这个项目的更广泛的目标是让研究生和本科生以尽可能多的方式接触跨学科的科学模型和多文化的研究社区，以便更好地为这些未来的地球科学家在21世纪世纪的研究挑战做准备。

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.