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Magmatic Co-Ni-Cu ores in the Norilsk ore field are related to the layered intrusions of trap formation with age 251 Ma (Kamo et al., 2003). Traps of the East Siberian Platform and underlying rocks were involved by the submergence zeolite and prehnite-pumpellyite facies metamorphism with the Rb/Sr age of 232-122 Ma (Spiridonov et al., 2000, 2006). Arsenides of Ni-Co-Fe impregnate the metamorphosed Co-Ni-Cu sulfide ores and hydrorthermal anhydrite-dolomite-calcite veins. Ni-Co arsenides occur in carbonate veins among the sulfide metaores. Fe arsenides and native arsenic occur in carbonate veins located both in the sulfide metaores and out of them. The arsenide-carbonate veins were deposited at T=216-127°C and P=0.9-0.1 kbar from NaCl-MgCl2 fluids with salinity of 6.5-12.6 wt.% eq NaCl. The Rb/Sr age of apophyllite from the arsenide-carbonate veins is 164 Ma, whereas of post-arsenide apophyllite, 122 Ma; the model Pb age of galena from the arsenide veins is 143-110 Ma. The source of Pb in galena of sulfide ores is mantle, whereas in galena from the metamorphic-hydrothermal arsenide-carbonate veins, crustal.
Rammelsbergite NiAs2 - lëllingite FeAs2 series. Continuous series of the lëllingite-rammelsbergite solid soutions was indetified in veins of the Noril'sk ore field for the first time (Gritsenko & Spiridonov, 2005). Lëllingite, which accomplishes the formation of each arsenide kidney and occurs as pods up to 35 cm in diameter, is the most abundant. Lëllingite associated with native arsenic contains (wt.%) 4 Co, 2 S, up to 3 Cu, and < 1 Ni. Lëllingite associated with arsenide is enriched in S (up to 12 wt.% S). The intermediate members of the series are abundant. Ni-lëllingite contains up to 10 wt.% Co. The Co-rich diarsenides are enriched in S; correlation coefficient between Co and S is +0.61 (n=112).
Rammelsbergite - safflorite CoAs2 series. Minerals are rare and are associated with Ni-Co-Fe triarsenides. The rammelsbergite-safflorite series is continuous; correlation coefficient between Ni and Co is -0.96. Safflorite is enriched in Fe; correlation coefficient between Co and Fe is +0.66 (n=62).
Krutovite NiAs2 - gersdorfite NiAsS series. This series is continuous. The As/S ratio ranges from 9 to 1. Krutovite contains up to 7 wt.% Co and up to 3 wt.% Fe.
According to experiments for dry systems, continuous series of Ni-Co-Fe diarsenides crystallize at T > 800°C (Roseboom, 1963). Thus, the formation temperature of arsenides from hydrothermal veins estimated from chemical composition of these minerals by diagrams of the synthetic dry systems is not correct.
Gritsenko Y.D., Spiridonov E.M. Memorials of continued raws rammelsbergite?lëllingite and rammelsbergite?safflorite in hydrothermal arsenide-carbonate veins of Norilsk ore field //ZVMO. 2005. P.134. N.1. P.53-68. (Rus).
Roseboom E.H. Co-Ni-Fe diarsenides: compositions and cell dimensions //Amer. Mineral. 1963. V. 48. P. 271-293.
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