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Flexural rigidity of the Basin and Range-Colorado Plateau-Rocky Mountain transition from coherence analysis of gravity and topographyStochastic inversion for flexural loads and flexural rigidity of the continental elastic layer can be accomplished most effectively by using the coherence of gravity and topography. However, the spatial resolution of coherence analysis has been limited by use of two-dimensional periodogram spectra from very large (greater than 10(exp 5)sq km) windows that generally include multiple tectonic features. Using a two-dimensional spectral estimator based on the maximum entropy method, the spatial resolution of flexural proerties can be enhanced by a factor of 4 or more, enabling more detailed analysis at the scale of individual tectonic features. This new approach is used to map the spatial variation of flexural rigidity along the Basin and Range transition to the Colorado Plateau and Middle Rocky Mountains physiographic provinces. Large variations in flexural isostatic responses are found, with rigidities ranging from as low as 8.7 x 10(exp 20) N m (elastic thickness (T(sub e) = 4.6 km) in the Basin and Range to as high as 4.1 x 10(exp 24) N m T(sub e) = 77 km) in the Middle Rocky Mountains. These results compare favorably woith independent determinations of flexural rigidity in the region. Areas of low flexural rigidity correlate strongly with areas of high surface heat flow, as is expected from the contingence of flexural rigidity on a temperature-dependent flow law. Also, late Cenozoic normal faults with large displacements are found primarily in area of low flexural rigidity region. The highest flexural rigidity is found within the Archean Wyoming craton, where evidence suggests that deeply rooted cratonic lithosphere may play a role in determining the distribution of tectonism at the surface.
Document ID
19950054983
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lowery, Anthony R.
(Univ. of Utah, Salt Lake City, UT United States)
Smith, Robert B.
(Univ. of Utah, Salt Lake City, UT United States)
Date Acquired
August 16, 2013
Publication Date
October 10, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: B10
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A86582
Funding Number(s)
CONTRACT_GRANT: NSF EAR-89-04473
Distribution Limits
Public
Copyright
Other

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