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Abstract Lithospheric layering contains critical information about continental formation and evolution. However, discrepancies on the depth distributions of lithospheric layers have significantly limited our understanding of possible tectonic connections among the layers. Here, we construct a high‐resolution shear velocity model of eastern North America using full‐wave ambient noise simulation and inversion by integrating onshore and offshore seismic datasets. Our new model reveals large lateral variations of lithosphere thickness approximately across the major tectonic boundaries, strong low‐velocity anomalies underlying the thinner lithosphere, and multiple low‐velocity layers within the continental lithosphere. We suggest that the present mantle lithosphere beneath eastern North America was formed and modified through multiple stages of tectonic processes, among which metasomatism may have significantly contributed to the observed intralithospheric low‐velocity layers. The sharp thickness variation of lithosphere promoted edge‐driven mantle convection, which has been consequently modifying the overlying mantle lithosphere and further sharpening the gradient of lithosphere thickness
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CUSRA2021: A Radially Anisotropic Model of the Contiguous US and Surrounding Regions by Full‐Waveform Inversion
Abstract The lithospheric structure of the contiguous US and surrounding regions offers clues into the tectonic history, including interactions between subducting slabs and cratons. In this paper, we present a new radially anisotropic shear wave speed model of the upper mantle (70–410 km) of the contiguous US and surrounding regions, constrained by seismic full‐waveform inversion. The new model (named CUSRA2021) utilizes frequency‐dependent travel time measurements, from 160 earthquake events recorded by 5,280 stations. The data coverage in eastern US is improved by incorporating more intraplate earthquakes. The final model exhibits clear and detailed shear wave speed anomalies correlating well with tectonic units such as North America Craton (high‐Vs), Cascadia subduction zones (high‐Vs), Columbia Plateau (low‐Vs), Basin and Range (low‐Vs), etc. In particular, the detailed structure of the North America Craton beneath Illinois basin is revealed. The depth of high‐Vs anomaly beneath the North America Craton correlates well with S‐to‐P receiver function and SH reflection results. Besides, the radial anisotropy in the Craton lithosphere shows a layering structure, which may relate to the process of lithospheric accretion and the origin of mid‐lithosphere discontinuities.
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- Award ID(s):
- 1942431
- PAR ID:
- 10420653
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Solid Earth
- Volume:
- 127
- Issue:
- 8
- ISSN:
- 2169-9313
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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