LAYERING OF FE-NI-CU SULFIDE MELTS: EXPERIMENTAL STUDY AND GEOLOGICAL IMPLICATIONS

Abstract

The experimental results obtained indicate that under certain conditions sulfide melt in fluid-bearing silicate-sulfide systems separates into a high-S Mss liquid (enriched in Fe and Ni) and a low-S liquid of Cp or Bn composition (enriched in Cu and Pt). This serves as evidence for formation of pyrrhotite-chalcopyrite drops in minerals and glasses of igneous rocks as a result of the layering of sulfide melt. It has been suggested that this mechanism plays an important role in igneous petrogenesis and ore formation. In particular, massive sulfide ore lodes up to 50 m thick in Noril'sk-type intrusions reveal mineralogical and geochemical zoning with separation of pyrrhotite and chalcopyrite zones.