Lithospheric Structure Across the Alaskan Cordillera From the Joint Inversion of Surface Waves and Receiver Functions

Embargo End Date
2019-04-09

Type
Article

Authors
Ward, Kevin M.
Lin, Fan-Chi

KAUST Grant Number
OCRF-2014-CRG3-2300

Date
2018-10-09

Abstract
The final deployment stage of the USArray Transportable Array is nearly complete with several years of high-quality broadband seismic data across the Northern American Cordillera already publicly available. This section of the Cordillera represents a rich history of tectonic deformation and accretion events as well numerous active tectonic processes. Many of these active tectonic processes such as uplift mechanisms or magmatic systems have been interpreted from structures imaged in regional or limited 2-D studies. To investigate the fully 3-D nature of the crust and uppermost mantle (<70 km), we present the results of a joint receiver function, surface wave inversion for the shear wave velocity structure across the Alaskan Cordillera. Integration of our new isotropic velocity model with existing data sets, including seismicity, gravity anomalies, and other seismic imagining methods, indicates that our velocity model is consistent with previous studies while providing unprecedented additional detail. A prominent feature in our model is a low-velocity mantle wedge. We suggest this low-velocity mantle wedge results from subducting slab lithosphere. The tectonic significance of this interpretation is that the velocity anomaly extends further to the east than slab seismicity does, suggesting that the downgoing slab extends further to the east, albeit aseismicly. This interpretation provides a simple explanation for the location of the active Wrangell volcanoes. We expect that our velocity model will be integrated with other mantle tomography models to further refine our understanding of this complex tectonic setting.

Citation
Ward, K. M., & Lin, F. (2018). Lithospheric Structure Across the Alaskan Cordillera From the Joint Inversion of Surface Waves and Receiver Functions. Journal of Geophysical Research: Solid Earth, 123(10), 8780–8797. doi:10.1029/2018jb015967

Acknowledgements
This research was supported by the National Science Foundation grants CyberSEES-1442665 and EAR-1753362 as well as the King Abdullah University of Science and Technology (KAUST) under award OCRF-2014-CRG3-2300. The authors acknowledge Carl Tape and Roy D. Hyndman for their thoughtful and constructive reviews of this manuscript. The facilities of the IRIS Data Management System, and specifically the IRIS Data Management Center, were used for access to waveform and metadata required in this study. The IRIS DMS is funded through the National Science Foundation and specifically the GEO Directorate through the Instrumentation and Facilities Program of the National Science Foundation under cooperative agreement EAR-1063471. Data used in this study can be found at the IRIS Data Management System (http://ds.iris.edu/ds/nodes/dmc/data/). The complete shear wave velocity model will be available from IRIS Data Services Products: Earth Model Collaboration (https://ds.iris.edu/ds/products/emc/). All figures were generated using the Generic Mapping Tool (GMT) software (Wessel et al.,).

Publisher
American Geophysical Union (AGU)

Journal
Journal of Geophysical Research: Solid Earth

DOI
10.1029/2018jb015967

Additional Links
https://onlinelibrary.wiley.com/doi/10.1029/2018JB015967

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