Melting of Fe-alloys and the thermal structure of the core

Citation:

Fischer R.A. 2016. “Melting of Fe-alloys and the thermal structure of the core.” In Deep Earth: Physics and Chemistry of the Lower Mantle and Core. American Geophysical Union / John Wiley and Sons. Publisher's Version

Abstract:

The temperature of the Earth’s core has significant implications in many areas of geophysics, including applications to Earth’s heat flow, core composition, age of the inner core, and energetics of the geodynamo. The temperature of the core at the inner core boundary is equal to the melting temperature of the core’s Fe-rich alloy at the inner core boundary pressure. This chapter is a review of experimental results on melting temperatures of iron and Fe-rich alloys at core conditions that can thus be used to infer core temperatures. Large discrepancies exist between published melting curves for pure iron at high pressures, with better agreement on the melting behavior of Fe–light element alloys. The addition of silicon causes a small melting point depression in iron, while oxygen and especially sulfur cause larger melting point depressions. The inner core boundary temperature likely falls in the range 5150–6200 K, depending on the identity of the light element(s) in the core, which leads to a core–mantle boundary temperature of 3850–4600 K for an adiabatic outer core. The most significant sources of uncertainties in the core’s thermal structure include the core’s composition, phase diagram, and Grüneisen parameter.

doi: 10.1002/9781118992487.ch1
ISBN: 9781118992487
ISBN: 9781118992470