DISLOCATION MELTING OF IRON AND THE TEMPERATURE OF THE INNER-CORE BOUNDARY, REVISITED

The melting point T(m) of iron at conditions of the Earth's inner core boundary (ICB) has been calculated from the dislocation theory of mel ting in metals. These calculations take into account the effects of pr essure at ICB conditions and of possible freezing point depression res ulting from dilution of pure iron in the outer core. Monte Carlo calcu lations have been used to estimate the uncertainties introduced by unc ertainty in the geophysical parameters that are used in the calculatio ns. With this approach T(m) of pure epsilon-Fe at a pressure of 330 GP a and without freezing point depression is 6160+/-250K, and 6110K for a 1000K freezing-point depression, T(m) of pure gamma-Fe is not signif icantly different; these values agree well with shock-wave determinati ons of T(m). The estimated temperature of the ICB is lower by the free zing point depression, perhaps by 500-1000K.