Conditions for a Once-Molten Earth to Cool

Abstract

Thermal history calculations have been made on a once-molten earth model: the earth is assumed to have undergone extensive melting in its early stage and the formation of the core and mantle with a proto-crust completed 4.5×10⁹ years ago. Necessary magnitude of thermal conductivity, including the radiative components, for such an earth to cool to the present state has been obtained in terms of the opacity value as 1-3cm^-1. If the earth's mantle became to consist of large crystals after the recrystallization, such a small value of opacity may be compatible with the results of thermal and optical measurements.