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.

该奖项是根据2021年《美国救援计划法》（公法117-2）全部或部分资助的。威廉·胡佛（William Hoover）博士已获得NSF耳朵博士后奖学金，以在华盛顿大学与导师凯利·康迪特（Cailey Condit）博士一起在华盛顿大学进行研究和教育计划。胡佛博士将研究水摇滚反应在产生神秘的地震现象中的作用，称为情景震颤和滑移（ETS），该现象可能是在大型，破坏性地震之前，尤其是沿俯冲带的断层。这项研究将重点关注来自Catalina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）中ETS的深度特征中发出的。综合的宏观和微尺度结构和地球化学分析将揭示流体流动的岩石改变如何产生ETS的变形行为特征。这项工作将为来自ETS源区域的岩石提供重要的直接观察，并为现代俯冲区监测和地震研究提供信息。在卡塔琳娜岛（Catalina Island）的现场工作中，胡佛博士将向西班牙裔美国河道岛群岛和心理顶石研究项目的学生教授野外课程。作为华盛顿大学Out K-12外展计划的一部分，他还将开发和介绍教育活动。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展活动返回研究的明显好处。 ETS的流变学模型建议它可以托管在代理滑石和绿色岩石片岩中，而胡佛博士将使用发掘的岩石记录检验这一假设。他将通过Catalina Schist（CA）的现场映射从ETS源区域（CA）的现场映射中推断出结构的地质等效物和富含流体的条件。他将将露头尺度变形分区连接到大量主要和痕量元素以及SR和LI同位素地球化学的变形变化。使用电子微束技术，使用空间分辨的微尺度化学和结构分析，他将确定变形机制，并将它们连接到所有尺度上的复合变化。这些观察结果该奖项反映了NSF的法定使命，并且我们是否使用基金会的知识分子优点和更广泛的影响审查标准来评估我们是否被认为是诚实的支持。

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

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.

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.