Experimental partitioning of uranium between liquid iron sulfide and liquid silicate: Implications for radioactivity in the Earth’s core

Measurable uranium (U) is found in metal sulfide liquids in equilibrium with molten silicate at conditions appropriate for a planetary magma ocean: 1–10 GPa, 1750–2100 °C, 0–28 wt% S, and fO2 2 log units below IW. However, the transfer of U from metal sulfide to silicate under our experimental conditions is so complete that insufficient U would remain so as to be of any importance to the core’s heat budget. U content in the sulfide phase increases strongly with S content but shows no significant variability with either pressure or temperature. Maximum DUsulfide/silicate is 0.001 while most values are considerably lower.