Enrichment of Rh, Ru, Ir and Os in Cr spinels from oxidized magmas: Evidence from the Ambae volcano, Vanuatu

Our results show that partitioning of Rh, Ru and Ir into Cr spinels increases with increasing oxygen fugacity, which suggests that the high concentrations of these elements in the Ambae Cr spinels are due to the high oxygen fugacity of the host magma. Therefore, Cr spinels may play an important role in controlling the concentrations of Rh and IPGEs during fractional crystallization of oxidized ultramafic-mafic magmas and during partial melting of oxidized arc mantle.