Phase diagram of iron, revised-core temperatures

[1] Shock-wave experiments on iron preheated to 1573 K from 14 to 73 GPa, yield sound velocities of the gamma- and liquid-phases. Melting is observed in the highest pressure (similar to71 +/- 2 GPa) experiments at calculated shock temperatures of 2775 +/- 160 K. This single crossing of the g- liquid boundary agrees with the gamma-iron melting line of Boehler [1993], Saxena et al. [1993], and Jephcoat and Besedin [1997]. This gamma-iron melting curve is similar to300degreesC lower than that of Shen et al. [1998] at 80 GPa. In agreement with Brown [2001] the discrepancy between the diamond cell melting data and the iron shock temperatures require the occurrence of yet another sub-solidus phase along the principal Hugoniot at similar to200 GPa. This would reconcile the static and dynamic data for iron's melting curve. Upward pressure and temperature extrapolation of the gamma-iron melting curve to 330 GPa yields 5300 +/- 400 K for the inner core-outer core boundary temperature.