Evaluation of the role of 410 km discontinuity as a redox filter in the upper mantle

Regions of low seismic velocity, linked to hydrous partial melting, have been detected at the top of the mantle transition zone (around 410 km deep). The buoyancy of these melts is influenced by their iron content, but there is a limited knowledge about how iron distributes between liquid and solid in these conditions. This study investigates how Fe3+ partitions between hydrous incipient melts and residual peridotite in the transition zone. Samples were synthesized under high-pressure conditions using a multi-anvil press and quenched into glass at pressures up to 12 GPa. These samples will be analyzed using micro-focused synchrotron Mössbauer spectroscopy, providing insights into Fe3+ compatibility in mantle melting. The findings will provide new constraints regarding the fate of the incipient melt at 410 km and its potential role for the redox evolution in the deep mantle.