The solubility of platinum in silicate melt under reducing conditions: Results from experiments without metal inclusions

The solubility of Pt in silicate melt was investigated at conditions of 2073-2573 K, 2 GPa and ∼IW −1.5 to +3.5. These are the first measurements of Pt solubility under conditions more reducing than the iron-wüstite buffer (IW) which are demonstrably free from contamination by metal-inclusions. Pt solubility increases with increasing temperature and decreasing oxygen fugacity. The ability of carbon to enhance Pt solubility under reducing conditions (3500 K. Under these conditions however, the estimated Pt/Os ratio is ∼40,000 times higher than that estimated for the PUM (Brandon et al., 2006). Instead, the PUM composition is generated most readily by metal-silicate equilibrium at more modest temperatures (∼3100 K), followed by a late accretion of chondritic material subsequent to core formation.