Diffuse Pacific-North American plate boundary: 1000 km of dextral shear inferred from modeling geodetic data

Geology
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Abstract

Geodetic measurements tell us that the eastern part of the Basin and Range Province expands in an east-west direction relative to stable North America, whereas the western part of the province moves to the northwest. We develop three-dimensional finite element representations of the western United States lithosphere in an effort to understand the global positioning system (GPS) signal. The models are constrained by known bounding-block velocities and topography, and Basin and Range Province deformation is represented by simple plastic (thermal creep) rheology. We show that active Basin and Range spreading by gravity collapse is expected to have a strong southward component that does not match the GPS signal. We can reconcile the gravitational component of displacement with observed velocity vectors if the Pacific plate applies northwest-directed shear stress to the Basin and Range via the Sierra Nevada block. This effect reaches at least 1000 km east of the San Andreas fault in our models.

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Publication type Article
Publication Subtype Journal Article
Title Diffuse Pacific-North American plate boundary: 1000 km of dextral shear inferred from modeling geodetic data
Series title Geology
DOI 10.1130/G32176.1
Volume 39
Issue 10
Year Published 2011
Language English
Publisher Geological Society of America
Description 4 p.
First page 943
Last page 946
Country United States
State Nevada
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