Investigating the iron oxidation state in silicate melt using nano-focused synchrotron Mössbauer spectroscopy under deep magma ocean conditi

The redox conditions of the magma ocean on early Earth had a far-reaching impact on the composition and evolution of the silicate mantle and atmosphere. In this study, we propose to investigate the iron oxidation state of silicate melts under metallic-iron saturated conditions, for the first time, reaching pressures and temperatures up to 135 GPa and 5500 K, respectively. The samples will be synthesized in a laser-heated diamond anvil cell, simulating conditions corresponding to a deep magma ocean. Recovered samples, which exhibit micron-scale reacted areas, are then subjected to focused ion beam processing. The exposed quenched silicate melts will be analysed using nano-focused synchrotron Mössbauer spectroscopy, allowing us to determine their Fe3+/ΣFe ratios. Our results will offer new constraints regarding the composition and evolution of early Earth.