Sulfide Melt Silicate Melt Distribution Coefficients for Noble-Metals and Other Chalcophile Elements as Deduced from Morb - Implications for Partial Melting

Analyses of chalcophile elements in coexisting sulfide and glass of basalts from the FAMOUS area of the mid-Atlantic ridge have been obtained by combined instrumental and radiochemical neutron activation analysis and directly coupled plasma spectrometry of hand-picked separates. In one sulfide-rich sample, 526-1, both the glass and sulfides were analyzed for the noble metals. The sulfide melt-silicate melt Nernst partition coefficients determined for Au and Ir are 1.5-1.9 X 10(4) and 1.2-1.6 X 10(4), respectively. That for Pd is estimated to be 3.5 X 10(4). Partition coefficients for Ni are within the range 500-900, those for Co are between 26-51, and a single determination for Cu yields a value of 1383. The distribution coefficients for Ni, and possibly Cu and Co, are shown to be compositionally dependent.