Imaging Upper-Mantle Structure under USArray using Long - Period Reflection Seismology

利用长周期反射地震学在 USArray 下对上地幔结构进行成像

基本信息

批准号：
1829601
负责人：
Peter Shearer
金额：
$ 24.45万
依托单位：
University of California-San Diego Scripps Inst of Oceanography
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：
2018-07-15 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1829601&HistoricalAwards=false
关键词：
Imaging Upper Mantle Structure under

项目摘要

This project will study the structure of the mantle below the United States at depths up to 800 kilometers (500 miles). Researchers will use data provided by the USArray project, which deployed ~2000 seismic stations across the United States over a 7-year period. Scientists will analyze records from distant earthquakes, called teleseisms, which contain seismic shear waves that reflect off layers and other features in the upper-mantle. By applying methods similar to those used by the oil industry to resolve crustal layering and oil reservoirs, this project will provide 3D images of the deep subsurface below the contiguous United States (i.e., excluding Alaska and Hawaii). The analyses should have superior resolution compared to most existing studies and will help resolve outstanding questions regarding the composition and tectonic evolution of the North American continent. The project will support a postdoctoral researcher and an undergraduate summer student from a program designed to increase the diversity of students in Earth and ocean sciences career paths.This research will image upper-mantle structure under the contiguous United States using reflection-seismology methods applied to topside S-wave reverberations recorded by USArray. Products will include new maps of the 410- and 660-km mantle discontinuities, as well as shallower regional upper-mantle reflectors seen in many areas, and reflections off the ancient subducting Farallon slab. The results should help relate Farallon subduction to current and past tectonics in the western United States and clarify the role of the lithosphere-asthenosphere boundary with respect to the deep cratonic root of North America. Improved resolution of sharp changes in upper-mantle structure will help address these and other issues regarding mantle composition and dynamics. Because these results are sensitive to the impedance contrast (seismic velocity and density), they provide a useful complement to seismic receiver-function studies, which are primarily sensitive to the S velocity jump alone. Preliminary results suggest the proposed method provides an exciting new way to probe upper-mantle structure, particularly when integrated with other models and data constraints.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.

该项目将研究美国地下 800 公里（500 英里）深处的地幔结构。研究人员将使用 USArray 项目提供的数据，该项目在 7 年的时间里在美国各地部署了约 2000 个地震台。科学家将分析来自遥远地震的记录，称为远震，其中包含反射上地幔层和其他特征的地震剪切波。通过应用类似于石油工业解决地壳分层和油藏问题的方法，该项目将提供美国本土（即不包括阿拉斯加和夏威夷）下方深层地下的 3D 图像。与大多数现有研究相比，这些分析应该具有更高的分辨率，并将有助于解决有关北美大陆的组成和构造演化的悬而未决的问题。该项目将支持一名博士后研究员和一名本科生暑期学生，该项目旨在增加地球和海洋科学职业道路学生的多样性。这项研究将使用反射地震学方法对美国本土的上地幔结构进行成像。 USArray 记录的上部 S 波混响。产品将包括 410 公里和 660 公里地幔不连续面的新地图，以及在许多地区看到的较浅的区域上地幔反射体，以及古老俯冲法拉伦板片的反射。研究结果应有助于将法拉隆俯冲与美国西部当前和过去的构造联系起来，并阐明岩石圈-软流圈边界相对于北美克拉通深部根部的作用。提高上地幔结构急剧变化的分辨率将有助于解决有关地幔组成和动力学的这些问题和其他问题。由于这些结果对阻抗对比（地震速度和密度）敏感，因此它们为地震接收器函数研究提供了有用的补充，地震接收器函数研究主要仅对 S 速度跳跃敏感。初步结果表明，所提出的方法提供了一种令人兴奋的新方法来探测上地幔结构，特别是与其他模型和数据限制相结合时。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评估进行评估，被认为值得支持。影响审查标准。