Distinct crustal isostasy trends east and west of the Rocky Mountain Front

Handle URI:
http://hdl.handle.net/10754/597998
Title:
Distinct crustal isostasy trends east and west of the Rocky Mountain Front
Authors:
Schmandt, Brandon; Lin, Fan-Chi; Karlstrom, Karl E.
Abstract:
© 2015. American Geophysical Union. All Rights Reserved. Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion and ellipticity measurements. Crust thickness and elevation are weakly correlated across the contiguous U.S., but the correlation is ∼3-4 times greater for separate areas east and west of the Rocky Mountain Front (RMF). Greater lower crustal shear velocities east of the RMF, particularly in low-elevation areas with thick crust, are consistent with deep crustal density as the primary cause of the contrasting crust thickness versus elevation trends. Separate eastern and western trends are best fit by Airy isostasy models that assume lower crust to uppermost mantle density increases of 0.18 g/cm3 and 0.40 g/cm3, respectively. The former value is near the minimum that is plausible for felsic lower crust. Location of the transition at the RMF suggests that Laramide to post-Laramide processes reduced western U.S. lower crustal density.
Citation:
Schmandt B, Lin F-C, Karlstrom KE (2015) Distinct crustal isostasy trends east and west of the Rocky Mountain Front. Geophysical Research Letters 42: 10,290–10,298. Available: http://dx.doi.org/10.1002/2015GL066593.
Publisher:
Wiley-Blackwell
Journal:
Geophysical Research Letters
KAUST Grant Number:
OCRF-2014-CRG3-2300 (F.-C.L.)
Issue Date:
14-Dec-2015
DOI:
10.1002/2015GL066593
Type:
Article
ISSN:
0094-8276
Sponsors:
Seismic data used in the study are openly available from the IRIS DMC(http:/ds.iris.edu/ds/nodes/dmc/), and the 3D seismic model will be available through the IRIS Earth Model Collaboration (http://ds.iris.edu/ds/products/emc/). Steve Hansenprovided informal feedback. Two anonymous reviewers provided comments thatimproved the manuscript. This research was supported by NSF grant EAR-1315856(B.S.), NSF grant CyberSEES-1442665 (F.-C.L.) and the King Abdullah University ofScience and Technology (KAUST) under Award No. OCRF-2014-CRG3-2300 (F.-C.L.).
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Full metadata record

DC FieldValue Language
dc.contributor.authorSchmandt, Brandonen
dc.contributor.authorLin, Fan-Chien
dc.contributor.authorKarlstrom, Karl E.en
dc.date.accessioned2016-02-25T13:10:39Zen
dc.date.available2016-02-25T13:10:39Zen
dc.date.issued2015-12-14en
dc.identifier.citationSchmandt B, Lin F-C, Karlstrom KE (2015) Distinct crustal isostasy trends east and west of the Rocky Mountain Front. Geophysical Research Letters 42: 10,290–10,298. Available: http://dx.doi.org/10.1002/2015GL066593.en
dc.identifier.issn0094-8276en
dc.identifier.doi10.1002/2015GL066593en
dc.identifier.urihttp://hdl.handle.net/10754/597998en
dc.description.abstract© 2015. American Geophysical Union. All Rights Reserved. Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion and ellipticity measurements. Crust thickness and elevation are weakly correlated across the contiguous U.S., but the correlation is ∼3-4 times greater for separate areas east and west of the Rocky Mountain Front (RMF). Greater lower crustal shear velocities east of the RMF, particularly in low-elevation areas with thick crust, are consistent with deep crustal density as the primary cause of the contrasting crust thickness versus elevation trends. Separate eastern and western trends are best fit by Airy isostasy models that assume lower crust to uppermost mantle density increases of 0.18 g/cm3 and 0.40 g/cm3, respectively. The former value is near the minimum that is plausible for felsic lower crust. Location of the transition at the RMF suggests that Laramide to post-Laramide processes reduced western U.S. lower crustal density.en
dc.description.sponsorshipSeismic data used in the study are openly available from the IRIS DMC(http:/ds.iris.edu/ds/nodes/dmc/), and the 3D seismic model will be available through the IRIS Earth Model Collaboration (http://ds.iris.edu/ds/products/emc/). Steve Hansenprovided informal feedback. Two anonymous reviewers provided comments thatimproved the manuscript. This research was supported by NSF grant EAR-1315856(B.S.), NSF grant CyberSEES-1442665 (F.-C.L.) and the King Abdullah University ofScience and Technology (KAUST) under Award No. OCRF-2014-CRG3-2300 (F.-C.L.).en
dc.publisherWiley-Blackwellen
dc.subjectcontinental crusten
dc.subjectisostasyen
dc.subjectlower crusten
dc.subjectNorth Americaen
dc.titleDistinct crustal isostasy trends east and west of the Rocky Mountain Fronten
dc.typeArticleen
dc.identifier.journalGeophysical Research Lettersen
dc.contributor.institutionEarth and Planetary Sciences Department; University of New Mexico; Albuquerque New Mexico USAen
dc.contributor.institutionDepartment of Geology and Geophysics; University of Utah; Salt Lake City Utah USAen
kaust.grant.numberOCRF-2014-CRG3-2300 (F.-C.L.)en
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