Mechanisms of Platinum-Group Element Enrichment and the Nature of the Hydrothermal System at the Babbitt Deposit, Duluth Complex, Minnesota

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A continuation of research dealing with the distribution and genesis of PGE and the Babbitt Cu-Ni deposit, Duluth Complex Minnesota, is proposed. Our preliminary results indicate that throughout the basal zone mineralization at Babbitt, Ir, Os, Ru, Rh, and Re have behaved as relatively immobile elements, and their distribution is related to primary magmatic processes. Pt and Pd show very different behavior, exhibiting poor correlations with Cu and S, and strong evidence of remobilization. A PGE- enriched zone has been detected which is spatially removed from the area of highest grade Cu-Ni ore, and is characterized by anomalous @34S values, and sulfide-oxide mineralogy. Synchrotron X-ray microprobe studies reveal ppm quantities of Pd in copper minerals from high bulk Pd samples, and Pd-enrichment in mackinawite produced during hydrothermal alteration. Detailed studies of bulk rock and mineral chemistry, alteration reactions, and S, H, and O isotopes are proposed to delineate the relationship between the PGE-enriched zone and the remainder of basal zone mineralization. Microsampling of individual sulfide minerals will be pursued using laser ablation-mass spectrometry (@34S values) and synchrotron X-ray fluorescence microprobe techniques (PGE values). Progressive changes in the chemical and isotopic measurements. The possible involvement of an externally-derived fluid in PGE localization will also be investigated.