Anomalous PGE concentrations in ophiolitic chromites and Cu ores associated with basic and ultrabasic rocks of the Polar Urals, Russia

 

Jan Pašava, Ilja Knésl, Anna Vymazalová, Ivanovna Gurskaja, Leonid Kolbancev

Geoscience Research Reports 42, 2009 (GRR for 2008), pages 233–235

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Abstract

We studied ophiolitic Cr-ores at the Centralnoye I deposit and Cu ores at the Ozernoye deposit, associated with basic and ultrabasic rocks of the Keshorsk complex. Anomalous IPGE values (average 126 ppb) and a strong negative slope of mantle-normalized PGE patterns in chromites indicate the predominance of Ru-(Os)-Rh-Ir-bearing phases among the platinum group minerals (PGM) assemblage that is typical of mantle-hosted ophiolitic chromite ores. Low Pt values in chromites and increased Pt values in host dunites could reflect the presence of cumulus PGM grains. The studied Cu-ores of the Ozernoje deposit contain 0.14-0.63 wt.% Cu and 0.05-0.76 g/t ZPGE. Mineral paragenesis includes magnetite, chalcopyrite, cubanite, pyrrhotite and we also identified Pd, Pd-Te, Te-Ni and Ag-Te phases.