Summary

Palladium bismuthotellurides (merenskyite-michenerite-moncheite-melonite) of vari-able composition and platinum arsenides (sperrylite) are documented in several drill cores of the Las Aguilas ma®c-ultrama®c intrusion, San Luis province, central Argentina. The ma®c-ultrama®c rocks ranging in composition from harzburgite to dunite, lherzolite, norite, and gabbro, intruded an amphibolite facies basement causing locally granulite facies metamorphism. The platinum ± group minerals (PGM) identi®ed in these rocks occur in (1) unaltered orthopyroxene-rich, plagioclase- and spinel-bearing rocks which carry abundant base-metal sulphides (BMS), such as chalcopyrite, pentlandite, and pyrrhotite; and in (2) serpentinized olivine-rich zones along cracks, but always associated with BMS, spinel, serpentine, and secondary magnetite. Textural evidence suggests a primary magmatic origin as well as late-stage hydrothermal remobilization, transport, and deposition of the PGM. Geophysical exploration and geological ®eld work have delineated the extent of the Cu-Ni sulphide mineralization in the ma®c-ultrama®c intrusion underlain by a crystalline basement of Ordovician age. It is estimated that platinum-group-element (PGE) ± enriched zones of several meter