Eclogitization of continental lithosphere from subduction zone devolatilization

俯冲带脱挥发分对大陆岩石圈的榴辉岩化作用

• 批准号: 2323318
• 负责人: Shi Sim
• 金额: $ 38.23万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-11-01 至 2025-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323318&HistoricalAwards=false
• 关键词: Eclogitization; continental; lithosphere; subduction; zone

Subduction zones are regions where one tectonic plate slides and sinks beneath another, and they have been a major focus of research in the field of Earth Science due to their association with mountain-building and with natural hazards like earthquakes and volcanic eruptions. Improving the understanding of processes involving the sinking of these rocks into the Earth's interior, known as foundering, holds valuable insights for subduction zones and continental crust research. The foundering process requires the rocks are of greater density than their surroundings. This project will explore the processes controlling the transformation of rocks in the lower continental crust to greater density resulting from mineral transformations and the degree to which the process requires fluid-mediated reactions common in subduction zones. The results of this modeling study will be compared to rocks found in Norway that are thought to have returned to the surface after undergoing this densification process. The research project is led by an early career investigator, who will gain valuable experience by spearheading this study and mentoring a postdoctoral scholar. To ensure transparency and encourage collaboration beyond this project, all the project's data and results will be made publicly accessible, and their findings will be presented at conferences both nationally and internationally to a variety of audiences. This project will contribute to the training of undergraduate researchers, K-12 science teachers, and high school students from diverse backgrounds. This will be accomplished through providing hands-on research experience in Georgia Tech’s Summer Research Experiences for Undergraduates (REU) program, and collaboration with the Center for Education integrating Science, Mathematics, and Computing (CEISMC) to introduce coding and Earth Science concepts to K-12 students in the Atlanta Metro area. The Georgia Intern Fellowships for Teachers (GIFT) program will provide funding to support a K-12 teacher and high school students, enabling them to develop grade-appropriate teaching materials and science projects. These educational resources will be showcased at local science fairs, with the goal to inspire young minds and foster an early interest in Earth Science and coding. This project seeks to address a notable knowledge gap concerning the mechanisms behind mountain-building processes beneath the Earth's surface, known as orogenesis. The primary focus of this project is on understanding the role of reactive fluids and the thermodynamics of eclogitization in the deep crust. To accomplish this, the project aims to develop advanced models that integrate the thermodynamics of eclogitization with simulations of fluid flow. These models will enable researchers to investigate the interactions between fluids and the eclogitization process and determine the timescales associated with metamorphism and the sinking of the lithosphere. The project will consist of two interconnected numerical modeling studies. First, models of disequilibrium thermodynamics will be developed to capture the behavior of key mineral phases and reactions. These models will then be coupled with simulations of fluid flow and rock deformation. To validate and gain insights from the models, the researchers will compare the model outputs with the grain-scale to regional-scale structures observed in well-documented eclogites from Norway. This analysis will allow them to test the hypothesis that lithospheric foundering is a global phenomenon and a consequence of orogenesis. Moreover, the models will provide valuable information about the specific conditions under which eclogitization becomes thermodynamically favorable and the timescales required for significant accumulations of eclogite in the lower crust. The researchers will explore these processes across a diverse range of initial rock compositions, representing the wide variety found in the Earth's continental crust. Ultimately, the project aims to enhance our overall understanding of the complex metamorphic and metasomatic processes that occurs during mountain formation. This project was supported by both the Geophysics and the Petrology and Geochemistry programs.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.

俯冲带是一个构造板块滑动并下沉到另一个板块下面的区域，由于它们与造山活动以及地震和火山爆发等自然灾害有关，因此一直是地球科学领域研究的主要焦点。提高对这些岩石沉入地球内部的过程的理解，即所谓的沉没，为俯冲带和大陆地壳研究提供了有价值的见解。下沉过程要求岩石的密度大于周围环境。该项目将探索控制下大陆地壳中岩石转化为更大密度的过程，这些过程是由矿物转化引起的，以及该过程在多大程度上需要俯冲带中常见的流体介导反应。这项模拟研究的结果将与在挪威发现的岩石进行比较，这些岩石被认为是在经历了这种致密化过程后返回地表的。该研究项目由一名早期职业研究者领导，他将通过带头研究和指导一名博士后学者获得宝贵的经验。为了确保透明度并鼓励项目以外的合作，所有项目的数据和结果都将向公众开放，他们的研究结果将在国内和国际会议上向各种受众展示。该项目将有助于培养来自不同背景的本科研究人员、K-12科学教师和高中生。这将通过佐治亚理工学院本科生暑期研究体验（REU）项目提供实践研究经验，并与科学、数学和计算教育中心（CEISMC）合作，向亚特兰大地铁地区的K-12学生介绍编码和地球科学概念来实现。乔治亚州教师实习生奖学金（GIFT）项目将为一名K-12教师和高中生提供资金支持，使他们能够开发适合年级的教材和科学项目。这些教育资源将在本地的科学展览会上展出，目的是激发年轻人的思想，培养他们对地球科学和编程的兴趣。该项目旨在解决关于地球表面下的造山过程背后机制的显着知识差距，即造山作用。该项目的主要重点是了解反应流体的作用和地壳深部榴辉石化的热力学。为了实现这一目标，该项目旨在开发先进的模型，将榴辉化热力学与流体流动模拟相结合。这些模型将使研究人员能够研究流体与榴辉石化过程之间的相互作用，并确定与变质作用和岩石圈下沉相关的时间尺度。该项目将包括两个相互关联的数值模拟研究。首先，将建立不平衡热力学模型，以捕捉关键矿物相和反应的行为。然后，这些模型将与流体流动和岩石变形的模拟相结合。为了验证并从模型中获得更多的见解，研究人员将把模型的结果与挪威的榴辉岩中观察到的颗粒尺度和区域尺度的结构进行比较。这一分析将使他们能够验证这样一个假设，即岩石圈下沉是一种全球性现象，是造山运动的结果。此外，这些模型将提供关于榴辉岩在热力学上有利的具体条件和下地壳中榴辉岩大量聚集所需的时间尺度的有价值的信息。研究人员将在不同的初始岩石组成中探索这些过程，这些岩石组成代表了地球大陆地壳中发现的各种各样的岩石。最终，该项目旨在提高我们对山脉形成过程中发生的复杂变质和交代过程的整体理解。这个项目得到了地球物理和岩石地球化学两个项目的支持。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。