Shear Wave Splitting Discloses Two Episodes of Collision‐Related Convergence in Western North America

Seismic anisotropy imposes first‐order constraints on the strain history of crust and upper mantle rocks. In this study, we analyze the mantle seismic anisotropy of the Western Canada Sedimentary Basin using a new shear wave spitting data set consisting of 1,333 teleseismic arrivals from 82 seismic...

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Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2019-03, Vol.124 (3), p.2990-3010
Main Authors: Wu, Lei, Gu, Yu J., Chen, Yunfeng, Liang, Huaying
Format: Article
Language:English
Subjects:
Anisotropy
Anomalies
Asthenosphere
Canadian Cordillera
Convergence
Crustal stress
Earth mantle
Foothills
Geophysics
layered anisotropic fabrics
Lithosphere
Moho
Mountains
Orientation
Periodicity
S waves
Sedimentary basins
Seismic analysis
Shear
shear wave splitting
Splitting
Tectonics
Upper mantle
western Laurentia
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Summary:Seismic anisotropy imposes first‐order constraints on the strain history of crust and upper mantle rocks. In this study, we analyze the mantle seismic anisotropy of the Western Canada Sedimentary Basin using a new shear wave spitting data set consisting of 1,333 teleseismic arrivals from 82 seismic stations. The resulting 332 high‐quality measurements yield a regional mean apparent splitting time (i.e., the magnitude of anisotropy) of 1.1 ± 0.3 s and an average fast orientation (i.e., the direction of anisotropy) of 54.6° ± 17.2°, which favor a two‐layer anisotropic model based on the 90° back azimuthal periodicity in both parameters. The northeast trending fast orientations dominate the lower layer at lithospheric depths and are approximately parallel to the present‐day absolute plate motions (APMs; i.e.,
ISSN:2169-9313
2169-9356
DOI:10.1029/2018JB016352