The Vasilinovskoe Pt–Pd Occurrence: A New Type of Noble Metal Mineralization in the Urals

A new Vasilinovskoe Pt–Au–Pd occurrence found near the settlement of Kharp (Yamal-Nenets Autonomous Okrug) is described for the first time. The occurrence is related to amphibolized gabbroids and subordinate pyroxenites of the mostly Late Ordovician Kershor complex. These rocks host mineralization zones with a visible thickness of 0.5–50 m and 3–5 vol % (rarely more) of sulfides. The feldspar–quartz, epidote, and other veinlets are often present in areas with dispersed or small-pocket sulfide dissemination. According to the fire assay analysis, the Pd, Au, and Pt contents of sulfide-rich samples weighing 0.5–1.0 kg from low-sulfide zones reach 1.4, 0.8, and 0.2 g/t, respectively. The PGE minerals include abundant micron-sized Pd tellurides: merenskite PdTe 2 , temagamite Pd 3 HgTe 3 , kotulskite PdTe, and other noble metal compounds: sadberiite PdSb, arsenopalladinite Pd 8 (As,Sb) 3 , and others. In addition to these Pd minerals, the magnetite–chalcopyrite–pyrite assemblage contains microinclusions of native silver, native bismuth, and native tin. The late polysulfide–feldspar–carbonate–quartz assemblage hosts Au and Ag tellurides, native gold (including mercurious), Se-bearing argentite, and greenockite. The formation of noble metal assemblages is related to late magmatic processes, as well as the redistribution of ore matter by later magmatic hydrothermal fluids down to a temperature of ~250°С; the pressure decreased from ~0.9‒1.3 to ~0.4‒0.5 kbar.