Collaborative Research: Identifying shallow slow slip using hematite textures and (U-Th)/He thermochronometry of exhumed and experimental faults

合作研究：利用赤铁矿结构和挖掘出的断层和实验断层的 (U-Th)/He 测温法识别浅层慢滑移

• 批准号: 2039700
• 负责人: James Hirth
• 金额: $ 14.21万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2039700&HistoricalAwards=false
• 关键词: Collaborative; Research; Identifying; shallow; slow

Slow slip, the movement along a fault without an earthquake, is a fundamental part of the seismic cycle. In the near-surface environment, slow slip may impact a range of tectonic processes and seismic hazards, including reducing earthquake energy, controlling how earthquakes stop, and the intensity of ground shaking. A critical unknown is how the material properties of fault rocks control this phenomenon. This project focuses on a segment of the San Andreas fault that is overdue for a large earthquake and has experienced recent slow slip events. Investigators will make use of the unique textural and geochemical qualities of hematite, a common mineral in faults, to determine the prevalence, timing, and impact of slow slip along the southern San Andreas fault in Mecca Hills, California. Comparison of observations from natural hematite-coated faults with laboratory deformation experiments will document how hematite deforms to understand what governs where and why slow slip occurs. Data will be integrated into a new educational program, the Providence (Utah) to Providence (Rhode Island) Partnership, that will connect rural and urban students in different parts of the country and impact more than 450 elementary and middle school students. Research and broader impact activities will provide mentoring and role modeling opportunities for middle school through faculty levels, critical for expanding and diversifying the sciences through each stage of education and training.Hematite is a common mineral on fault surfaces and its textures and thermochronometry data patterns can characterize a range of fault behavior. This project tests the hypothesis that hematite on fault surfaces promotes shallow slow slip by comparing data from hematite-coated slip surfaces in upper crustal, bedrock fault damage zones from Mecca Hills, with results from deformation experiments at sub-seismic slip rates on both hematite gouge and natural fault surfaces. Multi-scale microscopy and spectroscopy of hematite (and comparisons to clay textures), hematite (U-Th)/He analyses, and 4He/3He thermochronometry will be used to investigate rate-dependent friction behavior of hematite, related fault slip temperatures, deformation mechanisms, and spatiotemporal patterns of past shallow fault slip. This research will generate bedrock material property data that are critical for realistic physics-based models integrating shallow slow slip into the seismic cycle. The Providence to Providence Partnership will connect eighth graders at the Center for Creativity, Innovation, and Discovery in rural Utah, situated in the Intermountain Seismic Belt, with fourth graders in urban Rhode Island, via Zoom teleconferences. Researchers and students will engage in annual virtual and field education modules on faults and earthquakes. Eighth graders in Utah will teach these concepts to rising Utah eighth graders and fourth graders in RI. This project also provides training and support for graduate and undergraduate researchers, as well as a postdoctoral fellow.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.

缓慢滑动，即沿断层沿着运动而不发生地震，是地震周期的基本组成部分。在近地表环境中，缓慢滑动可能会影响一系列构造过程和地震灾害，包括减少地震能量，控制地震停止的方式以及地面震动的强度。一个关键的未知因素是断层岩的物质性质如何控制这种现象。该项目的重点是圣安德烈亚斯断层的一段，该断层因大地震而逾期，并经历了最近的缓慢滑动事件。调查人员将利用断层中常见矿物赤铁矿的独特结构和地球化学性质，确定加州麦加山南部圣安德烈亚斯断层沿着缓慢滑动的普遍性、时间和影响。从自然的赤铁矿涂层故障与实验室变形实验的观察比较将记录赤铁矿如何变形，以了解是什么控制在哪里和为什么发生缓慢滑动。数据将被整合到一个新的教育项目中，即普罗维登斯（犹他州）到普罗维登斯（罗得岛）的伙伴关系，该项目将连接全国不同地区的农村和城市学生，影响450多名中小学生。研究和更广泛的影响活动将为中学到教师提供指导和角色建模的机会，这对于通过教育和培训的每个阶段扩展和多样化科学至关重要。赤铁矿是断层表面上的常见矿物，其纹理和热年代学数据模式可以表征一系列断层行为。该项目通过比较麦加山上地壳基岩断层破坏区的赤铁矿覆盖滑动面的数据，与赤铁矿泥和天然断层表面亚地震滑动速率下的变形实验结果，检验断层表面上的赤铁矿促进浅慢滑动的假设。多尺度显微镜和光谱学的赤铁矿（和粘土纹理的比较），赤铁矿（U-Th）/He分析，和4 He/3 He热年代学将被用来研究速率相关的摩擦行为的赤铁矿，相关的断层滑动温度，变形机制，和时空模式过去浅断层滑动。这项研究将产生基岩材料特性数据，这些数据对于将浅层缓慢滑动整合到地震周期中的基于物理的现实模型至关重要。普罗维登斯到普罗维登斯的合作伙伴关系将通过变焦电话会议将位于山间地震带的犹他州农村的创造力、创新和发现中心的八年级学生与罗得岛城市的四年级学生联系起来。研究人员和学生将参加关于断层和地震的年度虚拟和实地教育模块。犹他州的八年级学生将把这些概念教授给正在崛起的犹他州八年级学生和国际扶轮四年级学生。该项目还为研究生和本科生研究人员以及博士后研究员提供培训和支持。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。