Norilsk ore field: the new metamorphic-hydrothermal mineral association — pure zvyagintsevite and silver, hibbingite, Mn-hibbingite, siderite, sphalerite and phosgenite in the magmatogenic putoranite ores

Abstract

The unique magmatogenic putoranite ores are developed within deep horizons (>1750 m) of the northeastern flank of the October deposit in the Norilsk ore field. Th ese are coarse-grained putoranite aggregates with lamellaes of moihoekite and isolated pentlfndite disproportionation. The composition of putoranite is: [(Fe17.6–17.9Ni0.4–1.1Co0–0.1)18–19Cu15.8–17.0]35S32; the composition of moihoekite is: [(Fe17.8–18.0Ni0.2–0.3Co0–0.1)18.2– 18.3Cu17.7–17.8]36S32; pentlandite contains 1,75  wt% of Co, its composition is: (Ni4.41Fe4.36Co0.23)9S8. Ores hold pneumatolytic stannopalladinite Pd5CuSn2, polyarite Pd(Bi,Pb), plumbopolyarite Pd(Pb,Bi), tetraferroplatinum Pt2Fe(Fe,Cu,Ni), tulameenite Pt2Fe(Cu,Fe,Ni) and kustelite (Ag,Au). Bornite is widespread in tectonized ores, as well as late hibbingite and Mn hibbingite (Fe2+,Mn2+)2(OH)3Cl, siderite and Mn siderite (Fe2+,Mn2+)[CO3] aggregates, replaced magnetite and Cu-Fe-Ni sulphides. Pure zvyagintsevite Pd3Pb and native silver compose syngenetic inclusions in hibbingite and siderite aggregates. Similar zvyagintsevite replaces pneumatolytic polyarite and plumbopolyarite. Metamorphogenic-hydrothermal zvyagintsevite probably arose from their material. Th is zvyagintsevite is sharply diff erent from pneumatolytic zvyagintsevite by the absence of Pt, Sn, Bi, Sb and Hg in its composition. The first detected hypogenic phosgenite Pb2[Cl2/CO3] forms pseudomorphoses aft er galena, sometimes with hibbingite. Th e described low-temperature metamorphogenic-hydrothermal mineral association arose involving carbon dioxidechloride solutions in reducing conditions. Later metamorphogenic-hydrothermal hisingerite, bornite and barite, partially replacing hibbingite, siderite and Cu-Fe-Ni sulfides, arose with an increased fugacity O2.