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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.

缓慢滑动是地震循环的一个基本部分，也就是没有地震的断层上的运动。在近地表环境中，慢滑可能会影响一系列构造过程和地震灾害，包括降低地震能量、控制地震停止的方式和地面震动的强度。一个关键的未知数是断层岩的物质性质如何控制这一现象。该项目的重点是圣安德烈亚斯断层的一段，这段断层本应发生大地震，但最近经历了缓慢滑动事件。调查人员将利用赤铁矿独特的结构和地球化学性质，确定沿着加利福尼亚州麦加山圣安德烈亚斯断层南部的缓慢滑动的普遍性、时机和影响。赤铁矿是断层中的一种常见矿物。将从天然赤铁矿覆盖的断层上观察到的结果与实验室的变形实验进行比较，将证明赤铁矿是如何变形的，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项目-普罗维登斯(犹他州)到普罗维登斯(罗德岛)伙伴关系中，该项目将连接全国不同地区的农村和城市学生，并影响到450多名中小学生。研究和更广泛的影响活动将为中学和教职员工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一种常见矿物，其结构和热力学数据模式可以表征一系列断层行为。该项目通过将麦加山上地壳基岩断层损毁带赤铁矿覆盖的滑动面的数据与赤铁矿断层泥和天然断裂面在亚震滑动速率下的变形实验结果进行比较，验证了断裂面上的赤铁矿促进浅层慢滑的假设。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热年代学将用于研究赤铁矿的速率相关摩擦行为、相关的断层滑动温度、变形机制和过去浅层断层滑动的时空模式。这项研究将产生基岩材料特性数据，这些数据对于将浅层慢滑结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伙伴关系将通过Zoom电话会议，将位于山间地震带的犹他州农村创意、创新和发现中心的八年级学生与罗德岛州市区的四年级学生联系起来。研究人员和学生将参与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正在崛起的犹他州八年级学生和国际扶轮四年级学生传授这些概念。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优势和更广泛的影响审查标准进行评估，被认为值得支持。