Mantle dynamics in Mars and Venus: Influence of an immobile lithosphere on three-dimensional mantle convection
- Univ. of California, Los Angeles (USA)
- Los Alamos National Laboratory, NM (USA)
Numerical calculations of fully three-dimensional convection in constant viscosity, compressible spherical shells are interpreted in terms of possible convective motions in the mantles of Venus and Mars. The shells are heated both internally and from below to account for radiogenic heating, secular cooling, and heat flow from the core. The lower boundary of each of the shells is isothermal and shear stress free, as appropriate to the interface between a mantle and a liquid outer core. The upper boundary of each of the shells is rigid and isothermal, as appropriate to the base of a thick immobile lithosphere. Calculations with shear stress-free upper boundaries are also carried out to assess the role of the rigid surface condition. The ratio of the inner radius of each shell to its outer radius is in accordance with possible core sizes in both Venus and Mars. A calculation is also carried out for a Mars model with a small core to simulate mantle convection during early core formation. Different relative proportions of internal and bottom heating are investigated, ranging from nearly complete heating from within to almost all heating from below. The Rayleigh numbers of all the cases are approximately 100 times the critical Rayleigh numbers for the onset of convection. Cylindrical plumes are the prominent form of upwelling in the models independent of the surface boundary condition so long as sufficient heat derives from the core. Thus major volcanic centers on Mars, such as Tharsis and Elysium, and the coronae and some equatorial highlands on Venus may be the surface expressions of cylindrical mantle plumes.
- OSTI ID:
- 5445521
- Report Number(s):
- CONF-9001119-; CODEN: JGREA; TRN: 91-023759
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 95:B9; Conference: 4. international conference on Mars, Tucson, AZ (United States), 10-13 Jan 1990; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
MARS PLANET
GEOPHYSICS
VENUS PLANET
COMPRESSIBLE FLOW
CONVECTION
DYNAMICS
EARTH MANTLE
EARTH PLANET
HEAT TRANSFER
MATHEMATICAL MODELS
MORPHOLOGY
THREE-DIMENSIONAL CALCULATIONS
TOPOGRAPHY
VISCOSITY
VOLCANOES
ENERGY TRANSFER
FLUID FLOW
MASS TRANSFER
MECHANICS
PLANETS
640107* - Astrophysics & Cosmology- Planetary Phenomena