Collaborative Research: How have orogenesis, rifting, and recent mantle dynamics shaped the lithosphere beneath the New England Appalachians?

合作研究：造山运动、裂谷和最近的地幔动力学如何塑造新英格兰阿巴拉契亚山脉下方的岩石圈？

• 批准号: 2147463
• 负责人: Laura Webb
• 金额: $ 22.83万
• 依托单位: University of Vermont & State Agricultural College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147463&HistoricalAwards=false
• 关键词: Collaborative; Research; How; orogenesis; rifting

Continents represent a key component of the Earth’s plate tectonic system. Plate tectonics appears to be unique among all planetary bodies in our solar system and plays a crucial role in making our planet hospitable to life. Continents are formed and modified by fundamental plate tectonic processes, including volcanism, mountain-building, collisions with other continental masses, and rifting or breakup of supercontinents. Understanding the evolution of continental lithosphere (that is, the crust and uppermost mantle beneath continents) through time remains one of the most important challenges in Earth science. This project will study the processes that have shaped the continental lithosphere beneath the New England Appalachians through geologic time using a multi-disciplinary approach that includes seismic imaging of the crust and upper mantle, the analysis of geological structures, and dating the motion on ancient faults. The investigators will carry out detailed imaging using seismic waves from distant earthquakes measured at seismometers deployed in two linear arrays (one across New York and Massachusetts, the other across Vermont, New Hampshire, and Maine). They will pair their seismic imaging work with studies of geologic structures exposed at the surface that will provide essential context on its plate tectonic history. The integration of information obtained from both approaches will illuminate the processes that have shaped the lithosphere beneath New England through the geologic past, opening a window into how continental lithosphere evolves as a part of the Earth’s plate tectonic system.This project aims to understand how rifting, subduction, and terrane accretion have shaped lithospheric structure beneath New England: Does the lithosphere preserve a record of subduction and accretion or does lithospheric structure heal over time? How do subsequent accretion events overprint the structure of earlier collisions? How did Mesozoic rifting affect the structure of Paleozoic accretions? Are recent to ongoing mantle processes modifying the lithospheric structure? The investigators will analyze data from the NEST (New England Seismic Transects) experiment, a deployment of ~25 broadband seismometers that is configured to resolve crustal targets on length scales that are appropriate for direct linkage with geological structures. They will apply a suite of imaging techniques (receiver function analysis, body wave travel time analysis, wavefield migration imaging, and SKS splitting measurements) that will provide a comprehensive view of both the isotropic and anisotropic structure of the New England crust and upper mantle, including the region underlain by the so-called Northern Appalachian Anomaly (NAA). The U-Pb geochronology work will focus on the identification and analysis of xenocrystic (inherited) cores in zircon grains from arc plutonic and volcanic rocks from the Shelburne Falls and Bronson Hill arcs, in order to understand the history and timing of Taconic (and later) orogenic processes. The investigators will also conduct field work and structural analyses to investigate the extent and relative timing on frontal thrusts of basement massifs and the Taconic Mountains in western New England and New York, and the Connecticut Valley border fault system in central New England. They will constrain the timing of deformation by collecting and dating samples via 40Ar/39Ar geochronology from these regions, in order to determine how widespread reactivation of old faults (and displacement on new faults) has been throughout the region. The project emphasizes undergraduate involvement in cross-disciplinary research and field work, particularly by participants from groups that have been historically underrepresented in Earth science, enabled by collaboration among faculty at a liberal arts college and research institutions.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.

大陆是地球板块构造系统的关键组成部分，板块构造在我们太阳系的所有行星体中似乎是独一无二的，并且在使我们的星球适合生命的过程中发挥着至关重要的作用大陆是由基本的板块构造过程形成和改变的。包括火山活动、造山、与其他大陆块的碰撞以及超级大陆的裂谷或分裂。了解大陆岩石圈（即地壳和地壳）的演化。随着时间的推移，大陆下的最上地幔仍然是地球科学中最重要的挑战之一，该项目将使用包括地震成像在内的多学科方法，研究在地质时期内塑造新英格兰阿巴拉契亚山脉下方大陆岩石圈的过程。研究人员将利用部署在两个线性阵列（一个横跨纽约和一个）的地震仪测量的遥远地震的地震波来进行详细成像。马萨诸塞州、佛蒙特州、新罕布什尔州和缅因州的另一个）将他们的地震成像工作与地表暴露的地质结构研究结合起来，这将为其板块构造历史提供重要背景。阐明了在过去的地质过程中塑造新英格兰下方岩石圈的过程，为了解大陆岩石圈作为地球板块构造系统的一部分如何演化打开了一个窗口。该项目旨在了解裂谷、俯冲和俯冲是如何演化的。地体吸积形成了新英格兰下方的岩石圈结构：岩石圈是否保留了俯冲和吸积的记录，或者岩石圈结构是否随着时间的推移而愈合？随后的吸积事件如何覆盖早期碰撞的结构？中生代裂谷如何影响古生代吸积的结构？ ?最近正在进行的地幔过程是否改变了岩石圈结构？研究人员将分析 NEST（新英格兰地震横断面）实验的数据，该实验是一项部署约 25 个宽带地震仪被配置为在适合与地质结构直接连接的长度尺度上解析地壳目标，它们将应用一套成像技术（接收器函数分析、体波传播时间分析、波场偏移成像和 SKS 分裂）。测量），这将提供新英格兰地壳和上地幔各向同性和各向异性结构的全面视图，包括所谓的北阿巴拉契亚异常（NAA）下方的区域。 U-Pb地质年代学工作将侧重于识别和分析来自谢尔本瀑布和布朗森山弧的弧深成岩和火山岩的锆石颗粒中的异晶（继承）核心，以了解塔科尼克（及后来）的历史和时间研究人员还将进行实地工作和结构分析，以调查西部基底地块和塔科尼克山脉的锋面冲断的范围和相对时间。新英格兰和纽约，以及新英格兰中部的康涅狄格河谷边界断层系统，他们将通过 40Ar/39Ar 地质年代学从这些地区收集样本并测年，从而限制变形的时间，以确定旧断层重新活动的范围。该项目强调本科生参与跨学科研究和实地工作，特别是来自历史上在地球科学领域代表性不足的群体的参与者，这是通过文理学院教师之间的合作实现的。和该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

New insights into crustal and mantle structure beneath the New England Appalachians from temporary broadband seismic deployments and integration with geological constraints

通过临时宽带地震部署和与地质约束的结合，对新英格兰阿巴拉契亚山脉下的地壳和地幔结构有了新的认识

• 发表时间: 2022-10
• 期刊: AGU Fall Meeting Abstracts
• 作者: Long; M.D.
• 通讯作者: M.D.

POLYPHASE DEFORMATION RECORDED BY THRUSTS ALONG THE WESTERN EDGE OF THE BERKSHIRE MASSIF, MASSACHUSETTS

马萨诸塞州伯克希尔地块西缘的逆冲记录的多相变形

• DOI: 10.1130/abs/2023se-385867
• 发表时间: 2023-01
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Webb, Laura;Karabinos, Paul M.
• 通讯作者: Karabinos, Paul M.