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B. Travis (Los Alamos National Laboratory), G. Schubert (Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles), J. Palguta (Department of Earth and Space Sciences, University of California, Los Angeles)
Features on the surface of Europa may reflect non-uniform heating in an underlying ocean due to variations in heat flux at the top of the mantle. Pore water convection can generate a spatially heterogeneous heat flux in a fractured, permeable mantle. Continual stressing of mantle material by gravitational tides may allow significant permeability to exist despite the approximately 1~kbar confining overburden pressure at the mantle's surface. We use a computational model of Europa to determine the impact of hydrothermal convection on overall heat transport, ice shell thickness, and heat flux heterogeneity and magnitude at the mantle/ocean interface. Our model of Europa includes a core, a silicate mantle, an ocean layer, and an ice shell. Hydrothermal convection in the mantle, thermal diffusion, parameterized ocean flow and melting/freezing are the heat transport mechanisms included. Surface temperatures range from 52~K at the poles to 110~K at the equator. Total heating in the body consists of tidal dissipation in the mantle and core, radiogenic heating in the mantle, and tidal dissipation in the ice shell. Values for the total heating range from about 1 to 10~TW. We assume that the outer few hundred kilometers of the mantle are permeable, and use a value of 10~millidarcys, typical of the Earth at equivalent overburden depths. In initial 2-D and 3-D simulations for 1.3~TW total heating, the ice shell thickness ranges from 30 to 40~km, the ocean layer thickness is between 60 and 70~km, the ocean temperature is 7\circ\mathrm{C}, and vigorous convection occurs in the mantle as a mix of plumes and linear features roughly 40-100~km wide and lengths up to several hundred kilometers. This work was supported by a grant from the Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory and by the NASA Planetary Geology and Geophysics Program.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.