EAR-PF: What is the role of metasomatic alteration in subduction zone episodic tremor and slip?

EAR-PF：交代改变在俯冲带阵发性震颤和滑移中的作用是什么？

• 批准号: 2053033
• 负责人: William Hoover
• 金额: $ 17.4万
• 依托单位: Hoover, William Floyd
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2053033&HistoricalAwards=false
• 关键词: EAR; PF; What; role; metasomatic

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Dr. William Hoover has been awarded an NSF EAR postdoctoral fellowship to carry out research and educational plans at the University of Washington alongside mentor Dr. Cailey Condit. Dr. Hoover will investigate the role of water-rock reaction in producing the enigmatic seismic phenomena known as episodic tremor and slip (ETS) that can precede large, damaging earthquakes, particularly along subduction zone faults. This study will focus on rocks from Catalina Island (Southern California) exhumed from depths characteristic of ETS in modern subduction zones (e.g., Cascadia in Washington and Oregon). Integrated macro- and micro-scale structural and geochemical analysis will reveal how rock alteration by fluid flow yields deformation behavior characteristic of ETS. This work will provide important direct observations of rocks from ETS source regions and inform modern subduction zone monitoring and seismic research. During field work on Catalina Island, Dr. Hoover will teach a field course to students from Hispanic-serving institution Cal State Channel Islands and mentor capstone research projects. He will also develop and present educational activities as part of the University of Washington Rockin’ Out K-12 outreach program. Lastly, this research will be carried out on land of the Gabrielino-Tongva Tribe and he will return tangible benefits of the research through outreach events held for the tribe. Rheological modeling of ETS suggests that it may be hosted within metasomatic talc and chlorite schists, and Dr. Hoover will test this hypothesis using the exhumed rock record. He will identify geologic equivalents of the structures and fluid-rich conditions inferred from geophysical studies of ETS source regions through field mapping of the Catalina Schist (CA). He will connect outcrop-scale deformation partitioning to metasomatic changes with bulk major and trace element and Sr and Li isotope geochemistry. Using spatially-resolved micro-scale chemical and structural analysis with electron microbeam techniques, he will determine deformation mechanisms and connect them to compositional changes across all scales. These observations will be placed in the temporal context of the seismic cycle through bulk Li and intra-crystalline diffusion chronometry. Using this multi-scale approach Dr. Hoover will document how metasomatism controls deformation partitioning and mechanisms at the conditions of ETS in modern subduction zones. These results will inform future geophysical, theoretical and experimental studies of subduction zone seismicity.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.

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。威廉·胡佛博士被授予NSF博士后奖学金，与导师凯莉·康迪特博士一起在华盛顿大学开展研究和教育计划。胡佛博士将研究水岩反应在产生被称为幕式震颤和滑动（ETS）的神秘地震现象中的作用，这种现象可能发生在大的破坏性地震之前，特别是沿着沿着断层。这项研究将集中在卡塔利纳岛（南加州）的岩石，这些岩石是从现代俯冲带（例如，华盛顿和俄勒冈州的卡斯卡迪亚）。综合宏观和微观尺度的构造和地球化学分析将揭示流体流动如何使岩石蚀变产生ETS的变形行为特征。这项工作将提供对ETS源区岩石的重要直接观测，并为现代俯冲带监测和地震研究提供信息。在卡塔利纳岛的实地工作期间，胡佛博士将为来自西班牙裔服务机构加州海峡群岛的学生讲授实地课程，并指导顶点研究项目。他还将开发和目前的教育活动的一部分，华盛顿大学摇滚'出K-12外展计划。最后，这项研究将在Gabrielino-Tongva部落的土地上进行，他将通过为部落举办的外联活动回报研究的实际利益。ETS的流变学模型表明，它可能存在于交代滑石和岩石片岩中，胡佛博士将使用挖掘出的岩石记录来验证这一假设。他将通过对卡塔利纳片岩（CA）的实地测绘，确定从ETS源区的地球物理研究中推断出的结构和富含流体条件的地质等价物。他将把露头规模的变形分区与交代变化与大量的主要和微量元素以及锶和锂同位素地球化学联系起来。使用空间分辨的微尺度化学和结构分析与电子微束技术，他将确定变形机制，并将它们连接到所有尺度的成分变化。这些观测结果将被放置在地震周期的时间背景下，通过散装锂和晶内扩散测时。使用这种多尺度方法，胡佛博士将记录交代作用如何控制现代俯冲带ETS条件下的变形分区和机制。这些结果将为未来俯冲带地震活动性的地球物理、理论和实验研究提供信息。该奖项反映了NSF的法定使命，并被认为值得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来支持。

项目成果

Reaction-Induced Porosity in an Eclogite-Facies Vein Selvage (Monviso Ophiolite, W. Alps): Textural Evidence and In Situ Trace Elements and Sr Isotopes in Apatite.

榴辉岩相矿脉边缘中反应引起的孔隙度（蒙维索蛇绿岩，西阿尔卑斯山）：结构证据以及磷灰石中的原位微量元素和锶同位素。

• DOI: 10.1093/petrology/egac128
• 发表时间: 2023
• 期刊: Journal of Petrology
• 影响因子: 3.9
• 作者: Hoover, William F;Penniston-Dorland, Sarah;Piccoli, Philip;Kylander-Clark, Andrew
• 通讯作者: Kylander-Clark, Andrew

Episodic Slow Slip Hosted by Talc‐Bearing Metasomatic Rocks: High Strain Rates and Stress Amplification in a Chemically Reacting Shear Zone

含滑石交代岩的幕式慢滑移：化学反应剪切带中的高应变率和应力放大

• DOI: 10.1029/2022gl101083
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Hoover, W. F.;Condit, C. B.;Lindquist, P. C.;Moser, A. C.;Guevara, V. E.
• 通讯作者: Guevara, V. E.

Metasomatism and Slow Slip: Talc Production Along the Flat Subduction Plate Interface Beneath Mexico (Guerrero)

交代作用和慢滑移：沿着墨西哥（格雷罗）下方的平坦俯冲板块界面生产滑石

• DOI: 10.1029/2023gc010981
• 发表时间: 2023
• 期刊: Geosystems
• 作者: Lindquist, P. C.;Condit, C. B.;Hoover, W. F.;Hernández‐Uribe, D.;Guevara, V. E.
• 通讯作者: Guevara, V. E.