Postdoctoral Fellowship: EAR-PF: Investigating spatiotemporal variability of forearc mantle wedge serpentinization and rheology during non-steady state subduction

博士后奖学金：EAR-PF：研究非稳态俯冲过程中弧前地幔楔形蛇纹石化和流变学的时空变化

• 批准号: 2305636
• 负责人: Gabe Epstein
• 金额: $ 18万
• 依托单位: Epstein, Gabe S
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305636&HistoricalAwards=false
• 关键词: Postdoctoral; Fellowship; EAR; PF; Investigating

Dr. Gabe Epstein has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research aimed at constraining the causes, variability, and consequences of forearc mantle wedge hydration under the mentorship of Dr. Adam Holt at the University of Miami. At regions where two tectonic plates converge, subduction is the process by which the “subducting” plate thrusts beneath the “overriding” plate and then descends to great depths within the mantle of the Earth; this process occurs along ~50,000 km of coastline around the world including beneath the states of Washington and Alaska, the Island of Japan, and the west coast of South America. Mantle wedge hydration occurs when water is released from the subducting plate into the section of the Earth’s mantle that lies above the subducting plate (the forearc mantle wedge) and can only proceed if this forearc region of the mantle is cool enough for water-bearing minerals to be stable. Release of water from the subducting plate, and the associated wedge hydration, may contribute to the localization and intensity of arc volcanoes (e.g., the “ring of fire” surrounding the Pacific Ocean) and large magnitude earthquakes. Despite this potential importance of mantle wedge hydration, the temporal variability and consequences of this hydration are poorly resolved, often because the dynamic and time-dependent nature of subduction systems is typically neglected in studies that target these processes. This project will merge novel computational methods with laboratory analysis to investigate how fluid release and wedge hydration in forearcs contributes to subduction dynamics (e.g., the speed and shape of subduction zones), and the impacts such dynamics have on volcanism, seismicity, water storage in the mantle, and Earth’s long-term habitability. Utilizing the research findings, Dr. Epstein will develop a series of accessible, open-source, online learning modules aimed at broadening understanding of geoscience problems pertinent to society, welfare, and equity. The design of the modules will allow for participants (the public and high school to undergraduate students) to interact with large datasets and manipulate software code. Broadly, the learning outcomes will be to demonstrate connectivity between geoscience and other branches of research (natural and social sciences, engineering, art), and to highlight the myriad research endeavors of modern geoscientists (laboratory, computational, and field based). The research and broader impact goals will produce new avenues in interdisciplinary science and will contribute to the NSF goal of advancement of national welfare by enhancing both the scientific community’s and the general public’s understanding of natural disasters and the global, long-term water cycle.Dr. Epstein will merge open-sourced software (Python, Perple_X, and ASPECT) with chemical/rheological insights from the exhumed rock record to develop dynamic models of fluid release and concomitant forearc mantle wedge hydration over a range of subduction conditions to better constrain the extents, spatiotemporal variability, and chemical/geodynamic consequences of mantle hydration. The project goals are: (1) determine the relative timing and extents of wedge hydration during a subduction zone’s lifetime, and the associated spatio-temporal variability in mineralogy and viscosity, through geodynamic modeling; (2) perform microstructural observations of natural wedge serpentinites to characterize deformation mechanisms over a range of P-T conditions; and (3) use trace element ratios and stable isotope analysis to determine the relationship between fluid flow and deformation mechanism. These goals are iterative, with insights from (2) and (3) feeding back into the geodynamic model (1). Laboratory chemical (major and trace element, stable N isotope analysis) and crystallographic/rheologic data (in-situ characterization of deformation mechanisms, EBSD, and Raman spectroscopy) will be performed on samples representing mantle wedge serpentinites or close analogs from New Idria (California, USA; blueschist facies), Cemetery Ridge (Arizona, USA; amphibolite facies), and the Western Alps (Italy/France; greenschist through eclogite). It is expected that earliest phase(s) of the thermal evolution of subduction zones is responsible for stabilization of large volumes of hydrous material in the mantle wedge, and that the rheologic behavior of this material varies depending on the extents and distribution of hydration combined with the temperatures and rates of viscous deformation. Dissemination of the research will include development of a series of accessible, experiential, online learning modules hosted as Jupyter Notebooks (via Binder) and geared towards high school and undergraduate students with the aim of demonstrating the interplay among geoscience, chemistry, physics, and coding. The Universal Design for Learning (UDL) educational framework will be utilized to create an accessible and equitable learning environment throughout creation of the modules.This EAR-PF award was co-funded by the EAR Tectonics Program.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.

加贝·爱泼斯坦（Gabe Epstein）博士被授予NSF地球科学博士后奖学金，旨在进行旨在恢复迈阿密亚当·霍尔特（Adam Holt）心态下前臂楔形楔水合的原因，可变性和后果的研究。在两个构造板汇聚的区域，俯冲是“俯冲”板在“覆盖”板下方推下“俯冲”板的过程，然后降到地球地幔内的深度。这个过程发生在世界各地约50,000公里的海岸线上，包括华盛顿州和阿拉斯加州，日本岛以及南美西海岸的下方。当水从俯冲板释放到位于俯冲板上上方的地幔部分时，地幔楔形水分发生在地球壁块（前臂地幔楔）上，并且只有在地幔的前臂区域足够冷却以使水矿物矿物质才能保持稳定时，才能进行。从俯冲板中释放水以及相关的楔形水合作用，可能有助于弧火山的定位和强度（例如，太平洋周围的“火环”）和巨大的地震。尽管地幔楔形水分的潜在重要性，但这种水合的暂时变异性和后果仍无法解决，通常是因为俯冲系统的动态和时间依赖性性质通常在针对这些过程的研究中被忽略。该项目将将新颖的计算方法与实验室分析合并，以研究前臂中的流体释放和楔形水合如何促进俯冲动态（例如，俯冲带的速度和形状），以及这种动态对火山主义，地震性，地震中的储存，地幔和地球的长期可行性的影响。利用研究结果，爱泼斯坦博士将开发一系列可访问的开源，在线学习模块，旨在扩大对与社会，福利和公平性有关的地球科学问题的理解。模块的设计将允许参与者（公立和高中以本科生）与大型数据集进行互动并操纵软件代码。从广义上讲，学习成果将是展示地球科学与其他研究分支之间的连通性（自然和社会科学，工程，艺术），并突出现代地球科学家（基于实验室，计算和现场）的无数研究努力。研究和更广泛的影响目标将在跨学科科学方面产生新的途径，并通过增强科学界和公众对自然灾害和全球长期水周期的理解来提高国家福利的目标。 Epstein将合并开源软件（Python，Perple_x和Fack）与化学/流变学的见解，从耗散的岩石记录中，开发流体释放和伴随的前齿楔形水分的动态模型，以在一系列俯冲条件下更好地限制很大的，时空变异性的水平和化学/地球的水平和化学性化的效果。项目目标是：（1）确定俯冲带寿命期间楔形水合的相对时间和范围，以及通过地球动力建模的矿物质学和粘度的相关空间变异性； （2）对天然楔形蛇丁式进行微结构观测，以表征在一系列P-T条件下的变形机制； （3）使用痕量元素比和稳定的同位素分析来确定流体流与变形机理之间的关系。这些目标是迭代的，带有（2）和（3）回到地球动力学模型（1）的见解。实验室化学（主要和痕量元件，稳定的N同位素分析）和晶体学/流变数据（对变形机制的原位表征，EBSD和Raman光谱法）将对代表地幔楔蛇源性的样品或来自新IDRIA（加利福尼亚州的加利福尼亚州，USACERIONITION）的样品进行，calluesChistories intarize rueschib rueschib ridge ride，ariz rize;和西方阿尔卑斯山（意大利/法国；绿og子通过eclogite）。预计俯冲带热演化的最早阶段是负责稳定地幔楔中大量含水物质的稳定，并且该材料的流变性行为在水合的暴力和分布与温度和粘性变形的速率上的量表变化。该研究的传播将包括开发一系列可访问，经验丰富的在线学习模块，该模块托管为jupyter笔记本电脑（通过粘合剂），并致力于高中和本科生，目的是展示地球科学，化学，物理学和编码之间的相互作用。通用学习（UDL）教育框架将用于在整个模块的整个创建过程中创建一个可访问且公平的学习环境。此EAR-PF奖由EAR Tectonics计划共同资助。该奖项反映了NSF的法定任务，并通过使用基金会的知识优点和广泛影响来评估NSF的法定任务，并通过评估来获得珍贵的支持。