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

威尔逊周期范式是许多大陆岩石圈（构造板块的地壳和地幔部分）生长和变化模型的核心。这个循环包括海洋盆地的闭合、大陆的碰撞、大陆的裂谷和新海洋盆地的形成。北美东部提供了一个完整的大陆东成长记录，从罗迪尼亚超大陆的分裂到盘古大陆的合并，再到现代大西洋的形成。该地区提供了一个极好的机会，通过地质时间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型。虽然以前大陆碎片之间的表面边界已日益为人所知，但一个持久的问题涉及大陆岩石圈较深部分的生长和稳定所涉及的时间和过程。该项目的总体目标是整合高分辨率的地球物理和地质数据，为这一经典地区的大陆地壳和地幔岩石圈的生长建立一个真正的四维（空间和时间）模型。地震台站的密度和分布都很好，包括地球范围可移动阵列，北美东部边缘社区地震实验，以及许多长期运行的永久性地震台站。本研究旨在研究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，并解决该地区构造史上长期存在的开放性问题。在这个项目中发展的新模型和假设将对北美大陆的特征、地壳和地幔的深层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。该项目将支持一位早期职业女性地球科学家的职业发展，并帮助在马萨诸塞大学阿默斯特分校建立一个新的地震学小组。扩大地震学的研究和教学对五学院地质联合会吸引本科生和研究生具有突出的潜力。它将支持麻省理工学院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一个为期两周的夏季地震学教育研讨会中，目标是五个学院的本科生。这个项目的研究结果将通过女孩公司介绍给8 -12年级的女孩。尤里卡!项目（一个全国性组织），是马萨诸塞州霍利奥克女孩公司和马萨诸塞大学之间基于stem的强大合作。地表地质汇编将被上传，并提供给整个东海岸的学校、学院和大学，供批评、合作和教育使用。该项目旨在将北美东部岩石圈的内部结构与其构造历史联系起来，并对大陆组合和改造的性质进行广泛的推断。具体来说，本提案将解决以下科学问题：(1)什么是大陆岩石圈？我们能否识别出岩石圈块体和岩石圈内边界？边界结构的起源是什么？(2)主要的地壳边界在哪里？这些边界是否可以用碰撞（增厚）和造山带的伸展/掘出来解释？地质边界在多大程度上可以向深处延伸？北美大陆的主要地形是什么时候形成的？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。一个先进的波传播模拟和反演将提供一个强有力的方法来约束大陆岩石圈的三维地震特征。远震接收函数分析将用于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函数解决，并用于突出岩石圈变形模式。现有地质数据集的汇编和综合以及新的地面岩石样本的收集将补充地震成分。地质、年代学和地球化学数据集的系统整合将为构造格局的重新评估提供信息。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。

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.