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.

该项目将研究美国下方地幔的结构，深度高达800公里（500英里）。研究人员将使用USArray项目提供的数据，该项目在7年的时间内部署了2000年在美国的2000个地震站。科学家将分析遥远地震的记录，称为远程主义，其中包含地震剪切波，这些抗震波反射上层壳中的层和其他特征。通过应用与石油工业相似的方法来解决地壳分层和石油储层，该项目将提供连续美国下方深处的3D图像（即不包括阿拉斯加和夏威夷）。与大多数现有研究相比，分析应该具有较高的分辨率，并将有助于解决有关北美大陆的组成和构造演化的杰出问题。该项目将支持一名旨在增加地球和海洋科学职业学生多样性的计划的博士后研究人员和一名本科夏季学生。这项研究将使用适用于USArray录制的Topside S-Wave Reverberations的反思 - 理论方法在美国连续的美国在美国的上层巨大结构进行图像。产品将包括410公里和660公里的地幔不连续性的新地图，以及在许多地区看到的较浅的区域上层反射器，以及在古老的俯冲Farallon板上的反射。结果应有助于将法拉隆的俯冲与美国西部的当前和过去构造联系起来，并阐明岩石圈 - 亚赛圈边界相对于北美深层cratonic根的作用。改进的上层膜结构的急剧变化将有助于解决有关地幔组成和动态的这些问题。由于这些结果对阻抗对比度（地震速度和密度）很敏感，因此它们为地震接收器功能研究提供了有用的补充，这些研究主要对单独的速度跳跃敏感。初步结果表明，提出的方法为探测上膜结构提供了一种令人兴奋的新方法，尤其是在与其他模型和数据约束集成时。本奖反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响来评估的评估值得支持的。