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

威尔逊旋回范式是地球上大陆岩石圈（地壳和地幔部分的构造板块）生长和修改的许多模型的核心。这个循环包括海洋盆地的闭合、大陆的碰撞、大陆的断裂和新海洋盆地的形成。北美洲东部提供了一个完整的记录，记录了从罗迪尼亚超大陆的分裂到泛大陆的组装，再到现代大西洋的形成。该地区提供了一个极好的机会，以促进我们对大陆生长和演化的理解，通过地质时间，并已被用作典型的部分和模型的板块构造几十年。虽然前大陆碎片之间的表面边界越来越为人所知，但一个持续存在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，以便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情况都很好，包括EarthScope可移动阵列、北美东部边缘社区地震实验和许多长期运行的常设地震台站。该提案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，并解决有关该地区构造历史的长期未决问题。在这个项目中开发的新模型和假设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理解产生广泛的影响。 该项目将支持一个早期职业女性地球科学家的职业发展，并帮助马萨诸塞大学阿默斯特分校发展一个新的地震学小组。地震学研究和教学的扩大具有吸引五所大学地质学联合会的本科生和研究生的突出潜力。它将支持马萨诸塞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纳入为期两周的夏季地震教育研讨会，针对五所大学的本科生。该项目的调查结果将通过女孩公司介绍给8 - 12年级的女孩。尤里卡！计划（一个国家组织），一个强大的STEM为基础的合作女孩公司。来自霍利奥克、马萨诸塞州和马萨诸塞大学。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，以供评论，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，并对大陆组装和修改的性质进行广泛的推断。 具体而言，本建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块体和岩石圈内边界吗？边界结构的起源是什么？(2)主要的地壳岩石圈边界是什么/在哪里，这些边界是否可以用造山带的碰撞（增厚）和伸展/折返来解释？地质界线能延伸到什么程度？北美大陆的主要殖民地是什么时候增加的？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。先进的地震波传播模拟和反演技术将为研究大陆岩石圈三维地震特征提供有力的手段。遥测接收器功能分析将用于识别和描绘尖锐的速度/密度不连续性。横向变量和深度相关的各向异性将与接收器功能解决，并用于突出岩石圈变形的模式。现有地质数据集的汇编和综合以及新的地表岩石样本的收集将补充地震部分。地质、年代学和地球化学数据集的系统整合将为构造框架的重新评估提供信息。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.