The moon's thermal state and an interpretation of the lunar electrical conductivity distribution
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Heat convection, being a more general theory than conduction theory, compels one to give reasons for using the latter theory as the basis of thermal evolution studies. Such reasons are supplied by considerations of material rheology.
The specific case of the thermal regime of the Moon is first considered as a steady state problem. It is demonstrated that no plausible creep resistance of lunar material and heat generation is compatible with a purely conductive theory of lunar thermal evolution. The most plausible, steady state models give convective cores extending to within 200–300 km of the surface. The radial temperature gradients in such cores is virtually confined to a thermal boundary layer but averages to about a tenth of degree/km. The (steady) central temperature for the most plausible lunar rheologies lie between 600–1000°C. Such models are compatible with the first interpretations of lunar magnetometry. The case for considering the lunar thermal state as such a quasi-static state is discussed.
It is also predicted that in very local zones the viscous dissipation of the general circulation produces much higher temperatures. Chemical differentiation and seismicity would have their origin in such low viscosity zones.
KeywordsBoundary Layer Thermal State Viscous Dissipation Creep Resistance Thermal Regime
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