Modification of lithospheric structure via subduction, terrane accretion, and rifting: A case study beneath Connecticut

通过俯冲、地体增生和裂谷改变岩石圈结构：康涅狄格州下方的案例研究

基本信息

批准号：
1800923
负责人：
Maureen Long
金额：
$ 38.52万
依托单位：
Yale University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-06-15 至 2023-11-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1800923&HistoricalAwards=false
关键词：
Modification lithospheric structure via subduction

项目摘要

The bedrock geology of the eastern United States is extraordinary in its complexity. This complexity reflects a range of plate tectonic processes that have affected eastern North America over geologic time. These processes include the formation and breakup of supercontinents, the accretion of new landmasses onto the continental edge, and widespread volcanic activity due to subduction and continental rifting. The state of Connecticut, though relatively compact in area, represents a prime opportunity to study this range of fundamental Earth processes. This is because Connecticut's geology reflects several phases of mountain building and terrane accretion during the formation of the Appalachian Mountains and the Pangea supercontinent, as well as the later breakup of Pangea and the formation of the Atlantic Ocean basin. This project will use data from an array of 15 seismic stations deployed across northern Connecticut to study the deep structure of the crust and mantle beneath the state, using recordings of seismic waves from distant earthquakes. The team will use images of this deep structure to answer fundamental questions about how supercontinents are formed and break up, as well as how plate tectonic processes such as subduction, rifting, and terrane accretion affect the evolution of the crust and upper mantle. The project includes a component of outreach to high school science teachers, enabling teachers to spend one week in the field collecting data and learning about Connecticut geology, as well as developing a classroom exercise that uses seismic data from the project.The investigators will analyze data from the Seismic Experiment for Imaging Structure beneath Connecticut (SEISConn), a deployment of 15 broadband seismometers in a dense linear array across northern Connecticut. The array occupies a region of the Appalachian Orogen that encompasses a striking variety of accreted terrane structures, as well as the Hartford Basin, a Mesozoic rift structure resulting from the breakup of Pangea. They will apply a suite of imaging techniques to SEISConn data, focusing on the imaging of discontinuity structure, seismic velocity structure, and seismic anisotropy within the crust and lithospheric mantle. The project is motivated by three major science questions: 1) How did episodes of subduction and terrane accretion during Appalachian oogenesis affect crustal and mantle lithospheric structure, and how does present-day deep structure correspond to surface geology? 2) How was the structure of the crust and mantle lithosphere affected by (failed) rifting during the Mesozoic, and how does the structure beneath the Hartford Rift Basin compare to structure across the (ultimately successful) rifted margin of eastern North America? 3) How was the crust and mantle deformed during subduction, terrane accretion, and rifting? This project will apply a range of analysis techniques to SEISConn data, including P-to-S and S-to-P receiver function analysis, ambient noise tomography, wavefield migration imaging, and shear wave splitting. The final phase of the project will involve the testing of specific hypotheses about past tectonic processes that were formulated based on geologic observations. This project will support the continuation of the successful Field Experiences for Science Teachers (FEST) program at Yale, which provides one week of field seismology experience to Connecticut-based high school science teachers.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.

美国东部的基岩地质极其复杂。这种复杂性反映了在地质时期影响北美东部的一系列板块构造过程。这些过程包括超级大陆的形成和分裂、新大陆在大陆边缘的增生以及由于俯冲和大陆裂谷而引起的广泛火山活动。康涅狄格州虽然面积相对紧凑，但却是研究这一系列基本地球过程的绝佳机会。这是因为康涅狄格州的地质反映了阿巴拉契亚山脉和盘古大陆形成期间的造山和地体增生的几个阶段，以及后来盘古大陆的分裂和大西洋盆地的形成。该项目将利用部署在康涅狄格州北部的 15 个地震台阵列的数据，利用遥远地震的地震波记录来研究该州下方地壳和地幔的深层结构。研究小组将利用这种深层结构的图像来回答有关超级大陆如何形成和分裂的基本问题，以及俯冲、裂谷和地体增生等板块构造过程如何影响地壳和上地幔演化的基本问题。该项目包括对高中科学教师进行外展活动的一部分，使教师能够花一周的时间在现场收集数据并了解康涅狄格州地质学，以及使用该项目的地震数据开发课堂练习。研究人员将分析数据来自康涅狄格州地下成像结构地震实验 (SEISConn)，在康涅狄格州北部以密集的线性阵列部署了 15 个宽带地震仪。该阵列占据阿巴拉契亚造山带的一个区域，该区域包含各种引人注目的增生地体结构，以及哈特福德盆地（盘古大陆分裂形成的中生代裂谷结构）。他们将把一套成像技术应用于 SEISConn 数据，重点是地壳和岩石圈地幔内的不连续结构、地震速度结构和地震各向异性的成像。该项目的动机是三个主要科学问题：1）阿巴拉契亚卵子发生过程中的俯冲和地体增生事件如何影响地壳和地幔岩石圈结构，以及当今的深层结构如何与地表地质相对应？ 2）中生代期间（失败的）裂谷对地壳和地幔岩石圈的结构有何影响？哈特福德裂谷盆地下方的结构与北美东部（最终成功的）裂谷边缘的结构相比如何？ 3）在俯冲、地体增生和裂谷过程中，地壳和地幔是如何变形的？该项目将对 SEISConn 数据应用一系列分析技术，包括 P-to-S 和 S-to-P 接收器函数分析、环境噪声断层扫描、波场偏移成像和剪切波分裂。该项目的最后阶段将涉及测试根据地质观测提出的有关过去构造过程的具体假设。该项目将支持耶鲁大学继续成功实施科学教师现场经验 (FEST) 计划，该计划为康涅狄格州的高中科学教师提供为期一周的现场地震学经验。该奖项反映了 NSF 的法定使命，并被认为值得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来提供支持。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

First‐Order Transition in Appalachian Orogenic Processes Revealed by Along‐Strike Variation of the Moho Geometry

莫霍面几何的沿走向变化揭示阿巴拉契亚造山过程中的一阶转变

DOI：
10.1029/2023jb027024
发表时间：
2023-12
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
0
作者：
Luo, Yantao;Long, Maureen D.;Karabinos, Paul;Rondenay, Stéphane;Masis Arce, Roberto
通讯作者：
Masis Arce, Roberto

Evidence for a lithospheric step and pervasive lithospheric thinning beneath southern New England, northeastern USA

美国东北部新英格兰南部地区岩石圈阶梯和普遍岩石圈减薄的证据