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High-Temperature Deformation of Dry Diabase with Application to Tectonics on VenusWe have performed an experimental study to quantify the high-temperature creep behavior of natural diabase rocks under dry deformation conditions. Samples of both Maryland diabase and Columbia diabase were investigated to measure the effects of temperature, oxygen fugacity, and plagioclase-to-pyroxene ratio on creep strength. Flow laws determined for creep of these diabases were characterized by an activation energy of Q = 485 +/- 30 kJ/mol and a stress exponent of n = 4.7 +/- 0.6, indicative of deformation dominated by dislocation creep processes. Although n and Q are the same for the two rocks within experimental error, the Maryland diabase, which has the lower plagioclase content, is significantly stronger than the Columbia diabase. Thus the modal abundance of the various minerals plays an important role in defining rock strength. Within the s ample-to-sample variation, no clear influence of oxygen fugacity on creep strength could be discerned for either rock. The dry creep strengths of both rocks are significantly greater than values previously measured on diabase under "as-received" or wet conditions. Application of these results to the present conditions in the lithosphere on Venus predicts a high viscosity crust with strong dynamic coupling between mantle convection and crustal deformation, consistent with measurements of topography and gravity for that planet.
Document ID
20020001354
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mackwell, S. J.
(Pennsylvania State Univ. University Park, PA United States)
Zimmerman, M. E.
(Minnesota Univ. Minneapolis, MN United States)
Kohlstedt, D. L.
(Minnesota Univ. Minneapolis, MN United States)
Date Acquired
August 20, 2013
Publication Date
January 10, 1998
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 103
Issue: B1
ISSN: 0148-0227
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
Paper-97JB02671
Distribution Limits
Public
Copyright
Other

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