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Effects of a temperature-dependent rheology on large-scale continental extensionThe effects of a temperature-dependent rheology on large-scale continental extension are investigated using a thin viscous sheet model. A vertically-averaged rheology is used that is consistent with laboratory experiments on power-law creep of olivine and that depends exponentially on temperature. Results of the calculations depend principally on two parameters: the Peclet number, which describes the relative rates of advection and diffusion of heat, and a dimensionless activation energy, which controls the temperature dependence of the rheology. At short times following the beginning of extension, deformation occurs with negligible change in temperature, so that only small changes in lithospheric strength occur due to attenuation of the lithosphere. However, after a certain critical time interval, thermal diffusion lowers temperatures in the lithosphere, strongly increasing lithospheric strength and slowing the rate of extension. This critical time depends principally on the Peclet number and is short compared with the thermal time constant of the lithosphere. The strength changes cause the locus of high extensional strain rates to shift with time from regions of high strain to regions of low strain. Results of the calculations are compared with observations from the Aegean, where maximum extensional strains are found in the south, near Crete, but maximum present-day strain rates are largest about 300 km further north.
Document ID
19890065877
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sonder, Leslie J.
(California Institute of Technology Pasadena, United States)
England, Philip C.
(Oxford, University United Kingdom)
Date Acquired
August 14, 2013
Publication Date
June 10, 1989
Publication Information
Publication: Journal of Geophysical Research
Volume: 94
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
89A53248
Funding Number(s)
CONTRACT_GRANT: NAG5-842
CONTRACT_GRANT: NAS5-27229
CONTRACT_GRANT: NSF EAR-84-08352
Distribution Limits
Public
Copyright
Other

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