Investigating formation and modification of the continental lithosphere in eastern North America - integrating seismic and geologic data sets

威尔逊旋回模式是地球上大陆岩石圈(构造板块的地壳和地幔部分)增长和改造的许多模式的核心。这个循环包括海洋盆地的关闭、大陆的碰撞、大陆的裂谷和新海洋盆地的形成。北美东部完整记录了该大陆从罗迪尼亚超大陆解体到盘古大陆拼合，再到现代大西洋的形成过程。该地区提供了一个极好的机会，通过地质时代推进我们对大陆生长和演化的理解，几十年来一直被用作板块构造的类型剖面和模式。尽管以前的大陆碎片之间的表面边界越来越为人所知，但一个长期存在的问题涉及到与大陆岩石圈更深部分的增长和稳定有关的时间和过程。该项目的总体目标是整合高分辨率地球物理和地质数据，以建立这一经典地区陆壳和地幔岩石圈生长的真正四维(空间和时间)模型。地震台站的密度和分布都很好，包括地球望远镜可移动阵列、北美东部边缘社区地震试验和许多长期运行的永久地震台站。这一建议旨在调查北美东部大陆岩石圈的特征，确定不同构造单元(微板块)的边界，并解决关于该地区构造历史的长期悬而未决的问题。该项目开发的新模型和假说将对北美大陆的特征、深部地壳和地幔的性质以及我们对大陆生长和演化的总体理解产生广泛的影响。该项目将支持一名职业生涯早期的女地质学家的职业发展，并帮助在阿默斯特大学建立一个新的地震学小组。扩大地震学的研究和教学具有显著的潜力，可以吸引本科生和研究生进入五所大学地质联盟。它将支持马萨诸塞州大学本科生和研究生的培训。更广泛地说，这个项目的成果将被整合到为期两周的夏季地震学教育研讨会中，目标是五所大学的本科生。这个项目的发现将通过Girls Inc.Eureka介绍给8-12年级的女孩！该计划是马萨诸塞州霍利奥克市的Girls Inc.和马萨诸塞州大学之间以STEM为基础的强有力的合作。地表地质汇编将被上传并提供给东海岸的学校、学院和大学，供评论、合作和教育使用。该项目试图将北美东部岩石圈的内部结构与其构造历史联系起来，并对大陆组装和改造的性质做出广泛的推断。具体地说，这项提议将解决以下科学问题：(1)什么是大陆岩石圈？我们能识别出不同的岩石圈区块和岩石圈内边界吗？边界结构的起源是什么？(2)主要的地壳地体边界是什么/在哪里？这些边界可以用造山带的碰撞(加厚)和伸展/折返来解释吗？地质边界可以延伸到什么程度？北美大陆的主要地体是什么时候增加的？为了解决这些问题，该项目将开发北美东部地壳和地幔岩石圈的综合地震模型。先进的波传播模拟和反演将为约束大陆岩石圈的三维地震特征提供强有力的手段。远震接收功能分析将被用来识别和描绘急剧的速度/密度不连续。横向可变和深度相关的各向异性将用接收器函数来解决，并用于突出岩石圈变形的模式。汇编和综合现有地质数据集以及收集新的地表岩石样品将补充地震部分。地质、地质年代学和地球化学数据集的系统集成将为重新评估构造框架提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Wilson cycle paradigm is central to many models for the growth and modification of continental lithosphere (the crust and mantle parts of the tectonic plates) on Earth. The cycle involves the closing of ocean basins, collision of continents, rifting of continents, and formation of new ocean basins. Eastern North America provides a complete record of the eastward growth of the continent from the breakup of supercontinent Rodinia through the assembly of supercontinent Pangea to the formation of the modern Atlantic Ocean. The region provides a superb opportunity to advance our understanding of continental growth and evolution through geologic time, and has been used as a type section and model of plate tectonics for decades. Although the surface boundaries between former continental fragments are increasingly well known, a persistent question involves the timing and processes involved with the growth and stabilization of the deeper parts of the continental lithosphere. The overall goal of this project is to integrate high-resolution geophysical and geological data in order to build a truly four-dimensional (space and time) model for the growth of continental crust and mantle lithosphere in this classic region. The density and distribution of seismic stations are excellent, including the EarthScope Transportable Array, the Eastern North American Margin Community Seismic Experiment, and many long-running permanent seismic stations. This proposal aims to investigate the characteristics of continental lithosphere in eastern North America, to identify boundaries of distinct tectonic units (microplates), and to address long-standing open questions about the tectonic history of this region. New models and hypotheses developed in this project will have wide implications for character of the North American continent, the nature of the deep crust and mantle, and our understanding of continental growth and evolution in general. The project will support the career development of an early-career female geoscientist and help the development of a new seismology group at UMass Amherst. Expansion of seismology research and teaching has outstanding potential to attract undergraduate and graduate students at the Five-College Geology Consortium. It will support training of undergraduate and graduate students at UMass. More broadly, the outcome of this project will be integrated into a two-week Summer Seismology Education Workshop, targeting for the five-college undergraduate students. Findings from this project will be introduced to 8th-12th grade girls through the Girls Inc. Eureka! Program (a national organization), a strong STEM-based collaboration between Girls Inc. of Holyoke, MA and UMass. Surficial geologic compilations will be uploaded and made available to schools, colleges, and universities throughout the east coast for critiques, collaboration, and educational use.This project seeks to associate the interior structure of the eastern North American lithosphere with its tectonic history, and to draw broad inferences for the nature of continental assembly and modification. Specifically, this proposal will address the following scientific questions: (1) What is continental lithosphere? Can we identify distinct lithospheric blocks and intra-lithospheric boundaries? What are the origins of the boundary structures? (2) What/where are the major crustal terrane boundaries and can these be interpreted in terms of collision (thickening) and extension/exhumation of the orogen? To what extent can geological boundaries be extended to depth? When were the major terranes added to the North American continent? To address these questions, the project will develop a comprehensive seismic model of the crust and mantle lithosphere in eastern North America. An advanced wave propagation simulation and inversion will provide a powerful way to constrain the three-dimensional seismic features of the continental lithosphere. Teleseismic receiver function analysis will be used to identify and delineate sharp velocity/density discontinuities. Laterally variable and depth-dependent anisotropy will be resolved with receiver functions, and used to highlight patterns of lithospheric deformation. Compilation and synthesis of existing geological data sets, and collection of new surface rock samples will complement the seismic component. A systematic integration of geological, geochronological and geochemical data sets will inform a re-assessment of the tectonic framework.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.