Melting of iron up to core pressures determined by in-situ electrical resistance jump

Accurate determination of melting temperature for iron at megabars places upper limit of thermal profile for the Earth's core. Large variations exist in the determined melting temperature (T_m) of iron, which is mainly attributed to melting criteria. Here we employed a new melting criterion, electrical resistance jump at phase boundary, to study the melting behaviors of iron up to 140 GPa in laser-heated diamond anvil cells. The T_m of iron ranges from 2600-4300 K at pressures of 30-140 GPa. Three other criteria, plateaus in laser power-temperature relation, quench texture, and fluid flow, were used to crosscheck the melting results of iron and excellent consistence was achieved. The current results is in excellent agreement with Anzellini et al. (2013), where diffused signal in fast x-ray diffraction and plateaus in laser power-temperature relation were used to determine the T_m of iron. The likely reasons for the huge difference in T_m are wet pressure medium and chromatically dispersed radiation spectra.