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shapes of venusian 'pancake' domes imply episodic emplacement and silicic compositionThe main evidence available for constraining the composition of the large circular 'pancake' domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of Venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 Venusian domes to represent a sampling of many stages during the growth of domes with comparable histories, and by plotting aspect ratio versus total volume, we find that the shapes of the domes are most consistent with episodic emplacement. On Earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition, strengthening earlier inferences about the presence of evolved magmas on Venus.
Document ID
19930048265
Document Type
Reprint (Version printed in journal)
Authors
Fink, Jonathan H.
(NASA Headquarters Washington, DC United States)
Bridges, Nathan T.
(NASA Headquarters Washington, DC United States)
Grimm, Robert E.
(Arizona State Univ. Tempe, United States)
Date Acquired
August 16, 2013
Publication Date
February 19, 1993
Publication Information
Publication: Geophysical Research Letters
Volume: 20
Issue: 4
ISSN: 0094-8276
Subject Category
LUNAR AND PLANETARY EXPLORATION
Funding Number(s)
CONTRACT_GRANT: NAGW-529
CONTRACT_GRANT: NSF EAR-90-18216
Distribution Limits
Public
Copyright
Other