HR: 15:20h
AN: V53C-07    [Abstracts]
TI: Large topographic rises, coronae, large flow fields and large volcanoes on Venus: Evidence for mantle plumes?
AU: * Smrekar, S
EM: ssmrekar@jpl.nasa.gov
AF: JPL, 4800 Oak Grove Dr., Pasadena, CA 91024 United States
AU: Stofan, E
EM: ellen@proxemy.com
AF: Proxemy Research, 20528 Farcroft Lane, Laytonsville, MD 20882 United States
AB: Voluminous volcanic deposits at topographic rises, coronae, large flow fields and large volcanoes have led these features to be linked to mantle plumes. Topographic rises have broad, swell-like topography (typically $\sim$1800 km across, 1.5 km high), large positive gravity anomalies, and associated volcanism. Coronae are circular to irregular features (typically $\sim$300 km across, 1.0 km high), defined by their fracture annulus and associated with uplift and volcanism, followed by subsidence. Large volcanic flow fields ($>$30,000 km2) and large volcanoes ($>$100 km in diameter) are sites of voluminous outpourings of lava. We interpret the variations in styles of volcanism, surface deformation, topography and gravity signatures to indicate differences in the nature of the underlying thermal upwellings that formed these features. Most topographic rises are likely to be formed by primary or deep-seated plumes, while coronae and probably most volcanoes result from shallower upwellings or secondary plumes. Extension clearly plays a critical role in the formation of large flow fields, coronae and some large volcanoes. We do not interpret large flow fields to be related to plumes. There are a similar number of primary plumes on Earth and Venus, but Venus has a much larger number of secondary plumes. The increase number of secondary plumes on Venus may result from the lack of slab cooling at the core-mantle boundary, its lack of a low viscosity zone or its stronger lithosphere.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8147 Planetary interiors (5430, 5724)
DE: 5480 Volcanism (8450)
DE: 6295 Venus
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting