The partition of nickel between olivine, magma and immiscible sulfide liquid

The Ni contents of glasses in products of earlier experiments on the Ni partition between olivine and immiscible sulfide liquid have been determined, allowing the distribution coefficients for Ni Fe²⁺ exchange between sulfide and silicate (K_D 1), and olivine and silicate (K_D 2) to be calculated. Ni is relatively enriched in S-bearing Mg-silicate liquids by complexing with dissolved S. In consequence, K_D 1 and K_D 2 are systematically dependent on both silicate liquid and sulfide liquid composition. The present study re-affirms the reliability of the existing Ni partition data for coexisting olivine and sulfide and, therefore, supports the earlier conclusion that an immiscible sulfide liquid cannot be a normal product of upper-mantle magmatic processes. In S-bearing systems K_D 2 will be somewhat lower than the value for the corresponding S-free system, and this may account for the discrepancies between previously reported partition data.