EAR-PF: Fault-rock trapped-charge and 4He/3He thermochronometry: new paleothermometers to assess scales and rates of fault slip

EAR-PF：断层岩石俘获电荷和 4He/3He 测温仪：用于评估断层滑动规模和速率的新型古温度计

基本信息

批准号：
1952905
负责人：
Margaret Odlum
金额：
$ 17.4万
依托单位：
Odlum, Margaret
依托单位国家：
美国
项目类别：
Fellowship Award
财政年份：
2020
资助国家：
美国
起止时间：
2020-05-01 至 2024-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1952905&HistoricalAwards=false
关键词：
EAR PF Fault rock trapped

项目摘要

Dr. Margaret Odlum has been awarded the NSF EAR Postdoctoral Fellowship to carry out research as well as a professional development plan at Utah State University (USU) under the mentorship of Professors Alexis K Ault and Tammy Rittenour. The goal of the project is to develop new approaches to fingerprint past earthquakes in fault rocks. Pinpointing evidence of ancient seismicity is important for understanding earthquake processes and mechanics and building a more complete record of fault activity, which collectively inform hazard assessment in seismically active fault systems. Most of the energy during an earthquake is given off as heat, which imparts a thermal and/or chemical signature in fault rocks. Proposed research uses coupled luminescence properties of minerals and He isotope thermometry integrated with textural analysis to access the thermal record of earthquake events across the full range of seismic slip rates, as well as temporal and spatial scales to inform fault slip processes. Complementary age information provided by these methods will provide a more continuous record of deformation over historical to geological timescales which is essential to understand earthquake cycles in a particular fault. This research will be conducted on the Wasatch and Hurricane faults in Utah. These are young, seismically active faults that are adjacent to Utah’s two largest population centers along the Wasatch Front and in the Saint George region, respectively. New approaches developed here will create pathways for researchers to quantify the spectrum of fault slip behavior in other fault systems. Dr. Odlum’s professional development plan is aimed at growing STEM workforce and engaging women, an underrepresented group in Utah in STEM, in earthquake science research and geotechnical skill-building. A seismic hazards module developed in partnership with the Utah Geological Survey will impact students enrolled in the new USU GeoPaths program, and reach a wider undergraduate community by sharing the module with other universities located in the Intermountain Seismic Zone and Wasatch Front region, as well as online through the USU Geosciences webpage and GeoMinutes YouTube channel, thus extending the reach and impact of this work.The goal of this research is to develop new approaches to identify, quantify, and date frictional heating caused by seismic slip in the rock record across the full range of seismic slip rates (micrometers/sec to tens of meters/sec). Much (~90%) of the energy budget during an earthquake goes into work done overcoming frictional resistance and dissipates as heat. The magnitude of temperature rise across a fault is a function of slip velocity, material properties, and strain localization. Frictional heat, in turn, impacts these factors and the interplay between variables controls fault strength during the seismic cycle. Transient, elevated temperatures impart textural and/or geochemical signatures in fault rocks. This project will combine trapped-charge analysis on quartz and feldspar with hematite and apatite 4He/3He thermochronometry of fault surfaces and underlying host-rock to recover paleotemperatures associated with seismic slip. The seismically active Wasatch and Hurricane faults in Utah will be the first field sites for applying this novel approach. Both seismogenic normal faults have textural evidence of past coseismic frictional-heat, bulk hematite (U-Th)/He dates that reflect thermal resetting or mineralization during earthquake slip within the viable age range for trapped-charge thermochronometry (0.5 Ma), and pose seismic risk to large population centers in Utah. Coupled paleotemperature and textural information from fault surfaces will inform dynamic weakening mechanisms operative during coseismic slip and improve understanding of rheological changes to fault materials that accompany fault thermal evolution and in-situ earthquake mechanics and fault strength in the upper seismogenic zone. Complementary temporal information on fault slip from trapped-charge and 4He/3He thermochronometry will fill a critical temporal data gap between historical, geodetic, and paleo-seismic (1 - 10,000 years) and low-temperature thermochronometric (100,000 - 1,000,000 years) records of deformation, with direct applications to seismic hazards assessment. The new thermochronometric approach to extract coseismic fault temperatures and temporal constraints on deformation applied here is transferable to other fault systems, giving researchers new tools to access the record of fault slip across seismic slip rates.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.

Margaret Odlum 博士被授予 NSF EAR 博士后奖学金，在 Alexis K Ault 和 Tammy Rittenour 教授的指导下，在犹他州立大学 (USU) 开展研究和专业发展计划。该项目的目标是开发。在断层岩石中识别过去地震的新方法对于了解地震过程和力学以及建立更完整的断层活动记录非常重要，这些记录共同为地震活动断层系统的危险评估提供信息。地震期间的大部分能量以热量的形式释放，这在断层岩中赋予了热和/或化学特征。拟议的研究利用矿物的耦合发光特性和氦同位素测温法与结构分析相结合来获取地震事件的热记录。这些方法提供的补充年龄信息将提供历史到地质时间尺度上更连续的变形记录，这对于理解地震至关重要。这项研究将针对犹他州的瓦萨奇断层和飓风断层进行，这些断层是年轻的地震活跃断层，分别毗邻犹他州沿瓦萨奇前沿和圣乔治地区的两个最大的人口中心。这里开发的方法将为研究人员量化其他断层系统中断层滑移行为的范围创造途径。Odlum 博士的专业发展计划旨在增加 STEM 劳动力，并让女性（犹他州在 STEM 领域代表性不足的群体）参与地震科学研究和研究。与犹他州地质调查局合作开发的地震灾害模块将影响参加新的 USU GeoPaths 项目的学生，并通过与位于山间地震带和瓦萨奇前沿的其他大学共享该模块来影响更广泛的本科生群体。地区，以及通过 USU 地球科学网页和 GeoMinutes YouTube 频道在线，从而扩大了这项工作的范围和影响。这项研究的目标是开发新的方法来识别、量化和日期在整个地震滑移率范围内（微米/秒至数十米/秒），岩石记录中的地震滑移引起的摩擦热在地震期间大部分（~90%）的能量预算都用于克服摩擦阻力。断层上的温升幅度是滑动速度、材料特性和应变局部化的函数，反过来又会影响这些因素，并且变量之间的相互作用控制着地震周期中的断层强度。瞬态高温在断层岩石中提供结构和/或地球化学特征该项目将把石英和长石的俘获电荷分析与断层表面和底层主岩的赤铁矿和磷灰石 4He/3He 测温法结合起来，以恢复与地震滑移相关的古温度。犹他州地震活跃的瓦萨奇断层和飓风断层将是应用这种新方法的第一个现场地点，这两个地震正断层都有过去的文本证据。同震摩擦热、大块赤铁矿 (U-Th)/He 日期反映了地震滑移期间的热重置或矿化作用，在捕获电荷测温法的可行年龄范围内 (0.5 Ma)，并对犹他州的大型人口中心构成地震风险。来自断层表面的耦合古温度和结构信息将为同震滑移期间起作用的动态弱化机制提供信息，并提高对伴随断层热演化和原位地震力学的断层材料流变变化的理解。来自俘获电荷和 4He/3He 热测时法的断层滑动的补充时间信息将填补历史、大地测量和古地震（1 - 10,000 年）和低温热测时法之间的关键时间数据空白。（100,000 - 1,000,000 年）变形记录，直接应用于地震灾害评估。此处应用的用于提取同震断层温度和变形时间约束的热测时方法可转移到其他断层系统，为研究人员提供了新的工具来获取跨地震滑动速率的断层滑动记录。该奖项反映了 NSF 的法定使命，并被认为值得支持通过使用基金会的智力优点和更广泛的影响审查标准进行评估。

项目成果

期刊论文数量（3）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Investigation of quartz luminescence properties in bedrock faults: Fault slip processes reduce trap depths, lifetimes, and sensitivity

基岩断层中石英发光特性的研究：断层滑动过程降低了圈闭深度、寿命和灵敏度

DOI：
10.1016/j.radmeas.2022.106784
发表时间：
2022-07
期刊：
Radiation Measurements
影响因子：
2
作者：
Odlum, Margaret L.;Rittenour, Tammy;Ault, Alexis K.;Nelson, Michelle;Ramos, Evan J.
通讯作者：
Ramos, Evan J.

Shallow Rupture Propagation of Pleistocene Earthquakes Along the Hurricane Fault, UT, Revealed by Hematite (U‐Th)/He Thermochronometry and Textures

赤铁矿 (U-Th)/He 测温法和纹理揭示更新世地震沿 UT 飓风断层的浅层破裂传播