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The Spreading of Variable-Viscosity Axisymmetric Radial Gravity Currents: Applications to the Emplacement of Venusian 'Pancake' DomesThe Magellan images of Venus have revealed a number of intriguing volcanic features, including the steep-sided or 'pancake' domes. These volcanic domes or flows have morphologies that suggest formation by a single continuous emplacement of lava with a higher viscosity than that of the surrounding basaltic plains. Numerous investigators have suggested that such high viscosity is due to high silica content, leading to the conclusion that the domes are evidence of evolved magmatic products on Venus. However, viscosity depends on crystallinity as well as on silica content: high viscosity could therefore also be due to a cooler (and therefore higher crystal content) lava. Models of dome emplacement which include both cooling and composition factors are thus necessary in order to determine the ranges of crystallinity and silica content which might lead to the observed gross dome morphologies. Accordingly, in this study domes are modelled as radial viscous gravity currents with an assumed cooling-induced viscosity increase to include both effects. Analytical and numerical results indicate that pancake dome formation is feasible with compositions ranging from basaltic to rhyolitic. Therefore, observations of gross dome morphology alone are insufficient for determining composition and the domes do not necessarily represent strong evidence for evolved magmatism on Venus.
Document ID
19990014554
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Sakimoto, S. E. H.
(Johns Hopkins Univ. Baltimore, MD United States)
Zuber, M. T.
(Johns Hopkins Univ. Baltimore, MD United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1995
Publication Information
Publication: Journal of Fluid Mechanics
Publisher: Cambridge Univ. Press
Volume: 301
Subject Category
Lunar And Planetary Exploration
Funding Number(s)
CONTRACT_GRANT: NGT5-50587
CONTRACT_GRANT: NAGw-3697
Distribution Limits
Public
Copyright
Other

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