Crustal Structure and Evolution beneath the Colorado Plateau and the Southern Basin and Range Province: Results from Receiver Function and Gravity Studies

Author

Lamuail Bashir
Stephen S. Gao, Missouri University of Science and TechnologyFollow
Kelly H. Liu, Missouri University of Science and TechnologyFollow
Kevin Lee Mickus

Abstract

Over the past several decades, contrasting models have been proposed for the physical and chemical processes responsible for the uplift and long-term stability of the Colorado Plateau (CP) and crustal thinning beneath the Basin and Range Province (BRP) in the southwestern United States. Here we provide new constraints on the models by modeling gravity anomalies and by systematically analyzing over 15,500 P-to-S receiver functions recorded at 72 USArray and other broadband seismic stations on the southwestern CP and the southern BRP. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean V_p/V_s of 1.761 ± 0.014 and a mean amplitude (R) of P-to-S converted wave (relative to that of the direct P wave) of 0.181 ± 0.014 that are similar to a typical continental crust, consistent with the model that the thin crust was the consequence of lithospheric stretching during the Cenozoic. The CP is characterized by the thickest crust (42.3 ± 0.8 km), largest V_p/V_s (1.825 ± 0.009) and smallest R (0.105 ± 0.007) values in the study area. In addition, many stations on the CP exhibit a clear arrival before the P-to-S converted phase from the Moho, corresponding to a lower crustal layer of about 12 km thick with a mafic composition. We hypothesize that the lower crustal layer, which has an anomalously large density as revealed by gravity modeling and high velocities in seismic refraction lines, contributed to the long-term stability and preuplift low elevation of the Colorado Plateau.

Recommended Citation

L. Bashir et al., "Crustal Structure and Evolution beneath the Colorado Plateau and the Southern Basin and Range Province: Results from Receiver Function and Gravity Studies," Geochemistry, Geophysics, Geosystems, vol. 12, no. 6, American Geophysical Union (AGU), Jun 2011.

The definitive version is available at https://doi.org/10.1029/2011GC003563

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Basin and Range Province; Bouguer gravity; Colorado Plateau; continental crust; receiver function; Chemical stability; Models; Seismology; Tectonics; Colorado Plateau; Gravity

International Standard Serial Number (ISSN)

1525-2027

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2011 American Geophysical Union (AGU), All rights reserved.

Publication Date

01 Jun 2011