Ferric iron stabilization at deep magma ocean conditions

Fe2O3 produced in a deep magma ocean in equilibrium with core-destined alloy sets the early redox budget and atmospheric composition of terrestrial planets. Previous experiments (≤28 GPa) and first-principles calculations indicate that a deep terrestrial magma ocean produces appreciable Fe3+, but predict Fe3+/ΣFe that conflict by an order of magnitude. We present Fe3+/ΣFe of glasses quenched from melts equilibrated with Fe-alloy at 38-71 GPa, 3600-4400 K, analyzed by synchrotron Mössbauer spectroscopy. These indicate Fe3+/ΣFe of 0.056-0.112 in a terrestrial magma ocean with mean alloy-silicate equilibration pressures of 28-53 GPa, producing sufficient Fe2O3 to account for the modern bulk silicate Earth redox budget and surficial conditions near or more oxidizing than the iron-wüstite buffer, which would stabilize a primitive CO- and H2O- rich atmosphere.

Methods
The samples have been synthesized with LH-DAC at 38-71 GPa and 3600-4400 K. Quenched samples have been double polished, and the Fe3+/ΣFe ratios have been resolved from Energy domain SMS(E-SMS). 

This data set including the raw E-SMS spectra and the calibration file. Besides that, the python codes to calculate the LH-DAC experimental log fO2 values, to obtain the thermodynamic model parameters, to obtain the initial Fig 2, Fig 3, and Fig 4 have been provided.