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Venus' center of figure-center of mass offsetMagellan altimetry data reveal that the center of figure (CF) of Venus is displaced approximately 280 m from its center of mass (CM) toward 4.4 deg S, 135.8 deg E, a location in Aphrodite Terra. This offset is smaller than those of other terrestrial planets but larger than the estimated error, which is no more than a few tens of meters. We examine the possibility that the CF-CM offset is related to specific geologic provinces on Venus by deriving three simple models for the offset: a thick-crust model, a hotspot model, and a thick-lithosphere model. The offset caused by a region of thick crust depends upon the region's extent, the crust-mantle density contrast, and the thickness of excess crust. A hotspot-related offset depends on the extent of the thermally anomalous region and the magnitude of the thermal anomaly. Offset due to a region of thick lithosphere depends upon the extent of the region, the average temperature contrast across the lithosphere, and the amount of excess lithosphere. We apply the three models to Venus plateau-shaped highlands, volcanic rises, and lowlands, respectively, in an attempt to match the observed CF-CM offset location and magnitude. The influence of most volcanic rises and of Ishtar Terra on the CF-CM offset must be quite small if we are to explain the direction of the observed offset. The lack of influence of volcanic rises can be explained if the related thermal anomalies are limited to a few hundred degrees or less and are plume-shaped (i.e., characterized by a flattened sublithospheric `head' with a narrow cylindrical feeder `tail'). The unimportance of Ishtar Terra is most easily explained if it lies atop a significant mantle downwelling.
Document ID
19950058551
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bindschadler, Duane L.
(California Univ. Los Angeles, CA, United States)
Schubert, Gerald
(California Univ. Los Angeles, CA, United States)
Ford, Peter G.
(Massachusetts Inst. of Tech., Cambridge, MA United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1994
Publication Information
Publication: Icarus
Volume: 111
Issue: 2
ISSN: 0019-1035
Subject Category
Astrophysics
Accession Number
95A90150
Funding Number(s)
CONTRACT_GRANT: NAGW-3484
CONTRACT_GRANT: NAGW-2086
Distribution Limits
Public
Copyright
Other

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