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.

大陆代表了地球板构造系统的关键组成部分。板块构造在我们的太阳系中的所有行星体中似乎都是独一无二的，并且在使我们的星球可以住院的地球上起着至关重要的作用。大陆是通过基本板块构造过程形成和修改的，包括火山，山区建造，与其他连续质量的碰撞以及超强的裂痕或破裂。随着时间的流逝，了解连续岩石圈的演变（即下面的地壳和最高地幔）仍然是地球科学中最重要的挑战之一。该项目将使用多学科的方法研究通过地质时间来研究新英格兰阿巴拉契亚人在新英格兰阿巴拉契亚群落下的过程，其中包括对地壳和上层地幔的地震成像，地质结构的分析以及对古代断层进行运动的分析。研究人员将使用在部署在两个线性阵列中的地震仪（纽约和马萨诸塞州的一个地震仪）的地震仪中进行的地震波进行详细的成像，另一个是佛蒙特州，新罕布什尔州和缅因州）。他们将将其地震成像工作与在表面暴露的地质结构的研究相结合，这将为其板块构造历史提供基本背景。从两种方法中获得的信息的整合都将阐明在新英格兰通过地质的过去塑造岩石圈的过程，并为地球板块构造系统的一部分开辟了一个窗口，旨在了解连续岩石圈的发展。该项目的旨在，该项目旨在理解裂缝，俯冲，俯冲和地形构成新的岩石圈的构成岩石圈的形状，并在岩石上塑造了岩石圈的形状，并在岩石圈中塑造了岩石圈，并且在岩石圈中构成了岩石层的构造，而岩石层则是在岩石上塑造的，该元素是在岩石上塑造的。积聚还是岩石圈结构会随着时间的流逝而愈合？随后的积聚事件如何覆盖早期碰撞的结构？中生代的脱落如何影响古生代增生的结构？最近是否正在进行的地幔过程改变了岩石圈结构？研究人员将分析来自Nest（新英格兰地震样带）实验的数据，该实验的部署〜25个宽带地震仪，该仪仪配置为可以在适合与地质结构直接链接的长度尺度上解决地壳目标。他们将采用一套成像技术（接收器函数分析，体波旅行时间分析，波场迁移成像和SKS分裂测量），将对新英格兰甲壳和上层紧缩的各向同性和各向异性结构进行全面视图，包括由所谓的Northern Northern Applalachian Anmoma Anoma Anoma Anomaa（Naimana）。 U-PB地质学工作将重点关注从Shelburne Falls和Bronson Hill Arcs的耗载岩石和火山岩岩石中的异晶（遗传）核心的识别和分析，以了解Taconic（及以后）骨气过程的历史和时机。研究人员还将进行现场工作和结构分析，以调查新英格兰西部和纽约西部地下室块和塔科尼克山脉以及新英格兰中部的康涅狄格州谷边界断层系统的额叶和相对时机。他们将通过从这些区域通过40AR/39AR年代学收集和约会样本来限制变形的时机，以确定整个地区的旧断层的宽度重新激活（以及新故障上的位移）是如何在整个地区进行的。该项目强调本科参与跨学科研究和现场工作，尤其是来自历史上在地球科学领域代表性不足的团体的参与者，这是通过在一家文科学院和研究机构的教职员工之间的合作来实现的。这项奖项反映了NSF的法定任务，并通过评估了基金会的评估，并通过评估了基金会和广阔的范围。

项目成果

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
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Webb, Laura;Karabinos, Paul M.
• 通讯作者: Karabinos, Paul M.

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
• 期刊: AGU Fall Meeting Abstracts
• 作者: Long, M.D.