EAR-PF: Strength, deformation, and recovery of phyllosilicates: How do phyllosilicates accommodate large amounts of shear strain?

EAR-PF：页硅酸盐的强度、变形和恢复：页硅酸盐如何适应大量的剪切应变？

• 批准号: 2204417
• 负责人: Caroline Seyler
• 金额: $ 18万
• 依托单位: Seyler, Caroline Elizabeth
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204417&HistoricalAwards=false
• 关键词: EAR; PF; Strength; deformation; recovery

Dr. Caroline Seyler has been awarded an NSF EAR Postdoctoral Fellowship to conduct research at the University of Minnesota investigating the deformation and recovery mechanisms in phyllosilicates that help accommodate slip between tectonic plates. Phyllosilicates are a group of minerals that are incredibly common in the mature faults and shear zones that define plate boundaries from major strike-slip faults to subduction zones. They are also stable across a wide range of depths, persisting as clays near the surface, micas in the crust, and talc and serpentine in the mantle. Their crystal structure consists of sheets of atoms held together by weak interlayer bonding, making slip on these sheets an easy deformation mechanism. This style of deformation strengthens grains with increasing strain, however, phyllosilicates observed in nature are inferred to be weak, even after high strain. This project will determine how phyllosilicates remain weak at high strains through innovative deformation experiments. These results will connect the deformation mechanisms operating at the atomic- and grain-scale to the dynamic behavior of faults and shear zones. Beyond research, Dr. Seyler will mentor students through the Research Opportunities in Rock Deformation (RORD) REU at UMN and the Department of Mechanical Engineering’s capstone course. Dr. Seyler will also engage in ongoing outreach efforts through the university and organize outreach to students at the tribal colleges in Minnesota.Lithospheric strength profiles rely on lab-derived constitutive laws, but without well-constrained rheological models for the deformation mechanisms in common fault and shear zone materials, these models remain incomplete. High-strain and high-pressure deformation experiments will be performed on biotite to determine the deformation and recovery mechanisms operating in phyllosilicates and explain why phyllosilicate deformation may be more effective at accommodating large amounts of strain than predicted by dislocation theory. High-strain experiments will be conducted in torsion in the gas-medium Paterson apparatus at the University of Minnesota (UMN), and high-pressure Deformation-DIA experiments will be conducted at the Advanced Photon Source (APS) at Argonne National Laboratories. Microstructural analysis of deformed samples will utilize optical and electron microscopy as a diagnostic tool to identify active deformation and recovery mechanisms. These results will also be compared with the microstructures documented in phyllosilicate-rich plate boundary shear zones to ensure the reproduction of natural deformation microstructures in the lab. Improving our understanding of phyllosilicate mechanical behavior will result in better strength estimates and rheological parameters. These parameters are essential inputs for geodynamic models as well as for rupture modeling of the earthquake cycle that informs seismic hazard assessment.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.

卡罗琳·塞勒（Caroline Seyler）博士被授予NSF耳朵博士后研究金，以在明尼苏达大学进行研究，调查了叶状部硅酸盐的变形和恢复机制，以帮助适应构造板之间的滑移。 Phyllosilicates是一组矿物质，它们在成熟的断层和剪切区中非常普遍，这些矿物质从主要的滑移断层到俯冲带定义了板块边界。它们在各个深度上也是稳定的，在表面附近粘土，地壳中的云母以及地幔中的滑石粉和蛇纹石。它们的晶体结构由弱层间键合在一起的原子片组成，使这些床单上的滑倒成为简单的变形机制。然而，这种变形强度的晶粒随着应变而增加，即使在高应变之后，自然界中观察到的浮雕也是弱的。该项目将通过创新的变形实验来确定在高应变下如何在高应变下保持弱的纤维硅酸盐。这些结果将把在原子和晶尺度运行的变形机制与故障和剪切区的动态行为联系起来。除了研究之外，Seyler博士还将通过UMN和机械工程系的Capstone课程的ROCK FOROMATION（RORD）REU的研究机会进行心理学生。塞勒（Seyler）博士还将通过大学进行持续的宣传工作，并在明尼苏达州的部落学院与学生组织宣传。Lithospheric强度概况依赖于实验室衍生的本构法律，但没有受到良好影响的流变学模型，以实现常见和剪切区域材料中的变形机制，这些模型仍然不满。高压和高压变形实验将在Biotite上进行，以确定在苯硅酸盐中运行的变形和恢复机制，并解释为什么在可容纳大量应变的菌株时，叶斑硅酸盐的变形可能比通过脱位理论预测的大量应变更有效。明尼苏达大学（UMN）的气体帕特森设备的扭转中，将进行高素质实验，并将在Argonne National Laboratories的高级光子源（APS）上进行高压变形-DIA实验。变形样品的显微结构分析将利用光学和电子显微镜作为诊断工具来识别主动变形和恢复机制。这些结果也将与富含岩石硅酸盐的板块边界剪切区中记录的微观结构进行比较，以确保实验室中自然变形微观结构的再现。提高我们对Phyllosilicate机械行为的理解将导致更好的强度估计和流变参数。这些参数是地球动力学模型的重要输入，也是地震周期的破裂建模，该循环为地震危害评估提供了信息。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得支持的。