Collaborative Research: Multiscale Travel Time Tomography of the Mantle to 1000 km Depth Beneath the Western USA

合作研究：美国西部地下 1000 公里深度的地幔多尺度走时断层扫描

基本信息

批准号：
0951901
负责人：
Robert van der Hilst
金额：
$ 7.82万
依托单位：
Massachusetts Institute of Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2010
资助国家：
美国
起止时间：
2010-05-15 至 2013-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=0951901&HistoricalAwards=false
关键词：
Collaborative Research Multiscale Travel Time

项目摘要

Teleseismic data recorded across the western U.S. provide information on the structural nature of the mantle beneath North America, a volume of Earth's interior that has been shaped by a complex history of subduction of oceanic lithosphere. Tomography images high-velocity structures that are commonly attributed to subducted slabs but which are not as simple as expected from our current understanding of the geologic history of subduction. Hence, such images hold key information on the actual subduction history, the fate of young subducted slabs, and convective flow in the upper mantle and across the transition zone to the lower mantle. The area affected by the Laramide orogeny is now experiencing small-scale convection beneath most of the western U.S., and a presumed Yellowstone plume is (probably) interacting with subducted slab and small-scale downwellings. Understanding this richness of geological processes and resolving the individual structures from one another requires careful and accurate seismic imaging. The goal of this project is to test specific hypotheses about the complex history of the western U.S. by creating a comprehensive 3-D P-wave velocity model extending from the base of the crust to ~1000 km depth. The seismic modeling will combine all available local, regional, and global travel-time datasets with newly available constraints on crust and transition zone structure. In addition, it uses finite frequency techniques (where useful) and 3-D wave propagation techniques. This work supports two graduate students.

美国西部记录的远震数据提供了有关北美地幔结构性质的信息，北美地幔是地球内部的一部分，是由海洋岩石圈俯冲的复杂历史形成的。断层扫描成像的高速结构通常归因于俯冲板块，但根据我们目前对俯冲地质历史的理解，其并不像预期的那么简单。因此，这些图像掌握了有关实际俯冲历史、年轻俯冲板块的命运以及上地幔和穿过过渡带到下地幔的对流的关键信息。受拉拉米德造山运动影响的地区目前正在美国西部大部分地区下方经历小规模对流，并且推测黄石羽流（可能）正在与俯冲板片和小规模下降流相互作用。了解这种丰富的地质过程并相互解析各个结构需要仔细而准确的地震成像。该项目的目标是通过创建从地壳底部延伸至约 1000 公里深度的综合 3D P 波速度模型来测试有关美国西部复杂历史的具体假设。地震建模将把所有可用的本地、区域和全球走时数据集与地壳和过渡带结构的新可用约束结合起来。此外，它还使用有限频率技术（如果有用）和 3-D 波传播技术。这项工作支持两名研究生。