The adiabatic gradient and the melting point gradient in the core of the Earth

Abstract

The melting gradient and the adiabatic gradient throughout the core of the earth are compared. The temperature of melting of iron at pressures equivalent to the inner core-outer core boundary is estimated to be circa 4250°C with a melting point gradient of approximately 500° through the outer core. The adiabatic gradient through the outer core is estimated to be circa 1250°; therefore, for the outer core to be liquid, its temperature must be considerably above the temperature in adiabatic equilibrium with the inner-outer core boundary. The temperature distribution throughout the outer core is deduced to follow a melting point curve. This temperature distribution should provide a substantial inhibition to radial components of convection in the outer core.