Further efforts to limit lunar internal temperatures from electrical conductivity determinations.

A Monte Carlo procedure is used to generate a representative set of 18 electrical conductivity profiles that are consistent with published lunar transfer function data in the 10^-5 to 10^-3 Hz range. The electrical conductivity is most strongly constrained by these data in the 450-1350 km depth range. Published electrical conductivity data vs T data (extrapolated to higher and lower T) are applied to convert the 18 profiles into T profiles for a series of radially homogeneous olivine-pyroxene mixtures ranging from 100% olivine to 100% aluminous orthopyroxene. The 100% olivine composition yields selenotherms that approach the Ringwood-Essene solidus at depths near 500 km, while the addition of aluminous orthopyroxene in excess of 15-30 vol.% leads to cooler selenotherms that approach the solidus only at depths >1000 km. The shape of the T-depth profiles is not strongly sensitive to the olivine/pyroxene ratio if the assumption of radial homogeneity is valid at depths >450-500 km. It is concluded that present-day selenotherms calculated according to thermal history models indicate the greatest consistency with the model of Toksoz et al. (Moon & Planets, 18, 1978, pp 281-320), which assumes initial partial melting and differentiation to a depth of 500 km and radial heat transport by subsolidus convection only during the first b.y. of lunar history. -P.Br.