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

基本信息

批准号：
2039727
负责人：
Alexis Ault
金额：
$ 44.9万
依托单位：
Utah State 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=2039727&HistoricalAwards=false
关键词：
Collaborative Research Identifying shallow slow

项目摘要

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.

慢滑移（没有地震的情况下沿着断层的运动）是地震周期的基本组成部分。在近地表环境中，慢滑移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、控制地震停止以及地面震动的强度。一个关键的未知数是断层岩的材料特性如何控制这种现象。该项目重点关注圣安德烈亚斯断层的一段，该断层早该发生大地震，并且最近经历了慢滑动事件。研究人员将利用赤铁矿（一种断层中常见的矿物）独特的结构和地球化学特性，确定加利福尼亚州麦加山圣安德烈亚斯断层南部缓慢滑移的发生率、时间和影响。将天然赤铁矿覆盖断层的观测结果与实验室变形实验进行比较，将记录赤铁矿如何变形，以了解是什么控制了缓慢滑动发生的地点和原因。数据将被整合到一个新的教育计划中，即普罗维登斯（犹他州）到普罗维登斯（罗德岛州）的合作伙伴关系，该计划将连接全国不同地区的农村和城市学生，影响超过 450 名中小学生。研究和更广泛的影响活动将为中学至教师级别提供指导和角色示范机会，这对于通过教育和培训的每个阶段扩展科学和使其多样化至关重要。赤铁矿是断层表面的常见矿物，其纹理和热测时数据模式可以表征一系列故障行为。该项目通过比较麦加山上地壳基岩断层损伤区赤铁矿覆盖滑移面的数据与赤铁矿断层亚地震滑移率下的变形实验结果，检验了断层面上的赤铁矿促进浅层慢滑移的假设。和自然断层面。赤铁矿的多尺度显微镜和光谱（以及与粘土结构的比较）、赤铁矿 (U-Th)/He 分析和 4He/3He 测温法将用于研究赤铁矿的速率依赖性摩擦行为、相关的断层滑动温度、变形过去浅层断层滑动的机制和时空模式。这项研究将生成基岩材料特性数据，这些数据对于将浅层慢滑移集成到地震周期中的现实物理模型至关重要。普罗维登斯至普罗维登斯合作伙伴关系将通过 Zoom 电话会议将犹他州农村地区山间地震带的创意、创新和发现中心的八年级学生与罗德岛州城市的四年级学生联系起来。研究人员和学生将参加有关断层和地震的年度虚拟和现场教育模块。犹他州的八年级学生将向犹他州 RI 的八年级和四年级学生教授这些概念。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智力价值和更广泛的影响审查标准进行评估，被认为值得支持。