Collaborative Research: Lithosphere-scale anisotropic imaging across the Eastern North American Margin's ocean-continent transition

合作研究：横跨北美东部边缘海洋-大陆过渡的岩石圈尺度各向异性成像

• 批准号: 1753722
• 负责人: Zachary Eilon
• 金额: $ 18.35万
• 依托单位: University of California-Santa Barbara
• 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: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753722&HistoricalAwards=false
• 关键词: Collaborative; Research; Lithosphere; scale; anisotropic

The cycle of continent formation and subsequent breakup to build oceans is an essential aspect of plate tectonics and is one of the fundamental processes that shape the planet. Yet, there are several details of continental rifting that continue to elude us. Rifted margins, such as that which comprises the entire east coast of the United States, represent the contact between continental crust and oceanic crust that is formed during, and after, the breakup (in this case, the Atlantic Ocean formed as Africa moved away). These margins retain a record of the processes that led up to, coincided with, and followed continental breakup. This project will utilize existing onshore and offshore seismic data to study in detail the deformation that produced the modern day eastern U.S. The results will aid in assessing contemporary hazard and risks along the margin. This project supports the training of a graduate student at the University of California at Santa Barbara and at least one undergraduate student at the University of Arizona. It also supports outreach activities to several high schools in North Carolina that hosted seismic instruments that recorded earthquake data used in the analyses. This project aims to shed light on two fundamental scientific questions related to the structure, evolution, and on-going dynamics associated with the eastern North American passive rift margin (ENAM): 1) What is the structure of the lithosphere from top to bottom across the ocean-continent transition and how was it shaped by rifting processes? 2) What is the history of deformation both within and seaward of the passive margin, and how is present-day mantle flow controlled by the margin's structure? Depth-constrained 3-D anisotropic velocity models will be produced of the ENAM from crust to below the lithosphere-asthenosphere boundary (LAB). By employing different imaging techniques in sequence, we will create a suite of complementary models: a) 3-D isotropic shear velocity model from inversion of ambient noise and earthquake-generated surface waves; b) 1-D high-resolution velocity profiles using dispersion curves inverted jointly with S-p and P-s receiver functions sensitive to crust and mantle discontinuities; c) 3-D finite-frequency body-wave azimuthal anisotropy tomography using the surface wave tomography as a starting model. These models will be jointly interpreted to refine estimates of crustal thickness and LAB character across the margin in the context of geodynamical rifting models, as well as to understand deformational flow during rifting and margin maturation to the present day.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.

大陆形成和随后建造海洋的破裂的周期是板块构造的重要方面，也是塑造行星的基本过程之一。然而，有几个关于大陆裂谷的细节继续掩盖我们。裂痕的边缘（例如整个美国东海岸的边缘）代表了在分手期间和之后形成的大陆地壳与海洋地壳之间的接触（在这种情况下，随着非洲搬离，大西洋形成的大西洋）。这些利润保留了导致，恰逢大陆分手的过程的记录。该项目将利用现有的陆上和近海地震数据来详细研究产生现代美国东部的变形，结果将有助于评估利润率沿线的当代危害和风险。该项目支持加利福尼亚大学圣塔芭芭拉分校的研究生培训，并至少一名亚利桑那大学的本科生。它还支持向北卡罗来纳州的几所高中进行外展活动，这些活动托管了地震仪器，记录了分析中使用的地震数据。 该项目旨在阐明与与北美东部的被动裂痕边缘相关的结构，进化和正在进行的动态相关的两个基本科学问题（ENAM）：1）岩石圈从岩石圈从岩石圈从岩石层到底部的过渡的结构是什么，以及如何通过训练过程来塑造它？ 2）在被动边缘的内部和海中，变形的历史是什么？当今的地幔流如何由边缘结构控制？深度约束的3D各向异性速度模型将由eNAM产生从岩层到岩石圈 - 近心圈边界以下（LAB）。通过采用不同的成像技术，我们将创建一套互补模型的套件：a）来自环境噪声和地震生成的表面波的反转的3-D各向同性剪切速度模型； b）使用S-P和P-S接收器倒置对地壳和地幔不连续性敏感的分散曲线的1-D高分辨率速度曲线； c）使用表面波断层扫描作为起始模型，3-D有限频体方位角各向异性层析成像。这些模型将被共同解释为在地球动力裂变模型的背景下对地壳厚度和实验室特征的估计值进行完善，并了解在裂动和边缘成熟到今天的变形流动。这奖反映了NSF的法定任务，并通过使用基础的智力效果和宽阔的范围来评估支持NSF的法定任务，并具有值得评估的评估。

项目成果

Breaking Up Is Hard to Do, Especially for Continents

分手很难，尤其是对于大陆来说

• DOI: 10.1029/2021eo155889
• 发表时间: 2021
• 期刊: Eos
• 作者: Worthington, Lindsay;Shuck, Brandon;B�cel, Anne;Eilon, Zachary;Lynner, Colton
• 通讯作者: Lynner, Colton