EAR-PF: Tracking rocks from depth to the surface: Coupled (U-Th)/(Pb-He) dating of monazite

艾米丽·m·彼得曼博士获得了美国国家科学基金会地球科学博士后奖学金，在斯坦福大学开展一项研究和教育计划。这项研究将开发和校准一种新技术，从存在于许多岩石中的单一关键矿物中确定地壳内的颗粒路径。独居石是一种含铀和钍的磷酸盐，可以通过多种方法进行分析，以提供同位素年龄信息，这些信息与地壳停留期间高温结晶和随后的低温冷却的时间有关。此外，独居石的微量元素和同位素组成可以与地壳内的生长条件联系起来。通过结合所有这些信息，新开发的方法将提高我们定量重建地壳形成过程的时空性质的能力。这种利用独居石作为计时器来阐明大陆地壳形成和演化的综合分析，将影响广泛的地球科学学科，包括构造学、地貌学、变质岩石学、景观演化和大陆动力学。通过提高独居石同位素年龄分析的准确性和精密度，本研究将提高我们约束地壳演化地球动力学模型的能力。新方法的细节- -包括成分依赖效应的校准- -可能适用于其他技术，并应使整个地质年代学界受益。在这个项目中开发的研究方法将被整合到彼得曼在死亡谷教授的实地课程中。通过这门课程，本科生和研究生将学习如何收集样本，分析数据，并发表一篇论文，该论文限制了一条主要断层的变形时间，该断层暴露了北美西南部地壳的一些已知最深的暴露。这项研究的结果也将被纳入一个扩展演示，该演示使用偶联独居石计时技术提供一个动画模块，说明负责创造动态造山带（如喜马拉雅）的机制、时间和过程的速度。

Dr. Emily M. Peterman has been granted the NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at Stanford University. This research will develop and calibrate a new technique to determine particle paths within the crust from a single key mineral that is present in many rocks. Monazite is a uranium- and thorium-bearing phosphate that can be analyzed by multiple methods to provide isotopic age information that bear upon both the timing of high-temperature crystallization and subsequent lower-temperature cooling during crustal residence. Furthermore, the trace element and isotopic composition of monazite can be linked to growth conditions within the crust. By combining all of this information, the newly developed approach will improve our ability to quantitatively reconstruct the spatial and temporal nature of crust-forming processes.This comprehensive analysis of the use of monazite as a chronometer for elucidating the formation and evolution of continental crust will impact a broad range of geoscience disciplines, including tectonics, geomorphology, metamorphic petrology, landscape evolution and continental dynamics. By improving the accuracy and precision of monazite isotopic age analysis, this research will improve our ability to constrain geodynamic models of crustal evolution. The details of the new methodology - including the calibration of compositionally dependent effects - may have application to other techniques, and should benefit the geoochronologic community at large. Research methods developed in this project will be integrated into a field-based course to be taught by Peterman in Death Valley. Through this course, undergraduate and graduate students will be taught how to collect samples, analyze data, and publish a paper that constrains the timing of deformation along a major fault that exposes some of the deepest-known exposures of southwestern North American crust. The results from this study will also be incorporated into an outreach demonstration that uses coupled monazite chronometry to provide an animated module that illustrates the mechanics, timing and rates of processes responsible for creating dynamic orogens such as the Himalaya.