16 New Data on Minerals. М., 2007. Volume 42 FERROSKUTTERUDITE1, NICKELSKUTTERUDITE, and SKUTTERUDITE FROM THE NORILSK ORE FIELD Ernst M. Spiridonov Lomonosov Moscow State University, Moscow, [email protected] Yulia D. Gritsenko Lomonosov Moscow State University, Moscow, [email protected] CoNiFe triarsenides skutterudite, nickelskutterudite and ferroskutterudite have been identified in the Norilsk ore field for the first time. They are hosted in the apophyllite–anhydrite–dolomite–calcite metamorphic hydrothermal veins that occur within the proximal zone of the magmatic CoNiCu sulfide ores, which have been affected by epigenetic prehnitepumpellyite and zeolite facies metamorphism. The CoNiFe triarsenides have overgrown the CoNi diarsenide segregations with which they form complex intergrowths. Both skutterudite and nickelskutterudite, and skutterudite and ferroskuterudite, from Norilsk form continuous isomorphic series. Clear negative correlation between Ni and Fe and strong positive correlation between Co and Fe and Co and S have been identified. 6 tables, 12 figures, 25 references. A wide range of isomorphic substitutions of Spiridonov et al., 2000; Gritsenko & Spiridonov, FeCoNi is characteristic of the iron, cobalt 2005a, 2005b, 2006). The skutteruditegroup and nickel chalcogenides, including sulfides, minerals are characteristic of CoNiAgBiU sulfoarsenides, arsenides and other com- deposits and NiCo arsenide deposits pounds. Frequently, there are continuous (Schneiderhö n, 1955; Krutov, 1959; Petruk et series of solid solutions including disulfides: al., 1971; Shishkin, 1973; Rudashevsky et al., pyrite – vaesite NiS2 – cattierite CoS2, 1975, 1976; Fanlo et al., 2004). diarsenides: safflorite CoAs2 – rammelsbergite NiAs2 – loellingite FeAs2 (Krutov, 1959; NORILSK ORE FIELD Shishkin, 1973; Vaughan & Craig, 1978; Vinogradova, 2002; Gritsenko & Spiridonov, The Norilsk ore field is located in the plate 2005a). Currently, triarsenides skutterudite cover of the PreRephean East Siberian Platform within the zone of marginal deformation. The CoAs3 – nickelskutterudite NiAs3 – fer- CoNiCu magmatic ores of the 250 ± 5 Ma age roskutterudite (Fe,Co)As3 are attributed to them. The continuous skutteru- are related to the gabbrodolerite intrusions of the ditenickelskutterudite series has been Upper Permian to Lower Triassic trap assem- described previously (Godovikov, 1959; blage (Godlevsky, 1959; Dodin et al., 1971; Roseboom, 1962; Radcliffe, 1968; Petruk et al., Genkin et al., 1981). Magmatic sulfides are dis- 1971; Rudashevsky et al., 1975, 1976; Vaughan seminated near the base (and at some other lev- & Craig, 1978; Vinogradova, 2002; Fanlo et al., els) of the Norilsk, Talnakh and Taimyr plutons 2004). and form massive orebodies, veins and impreg- The skutteruditegroup minerals, MeAs3, nations, mainly in the lower nearcontact crystallize at low sulfur activity from igneous rocks and adjacent wall rocks. The hydrothermal fluids and are the Asrichest are- Norilsk1 deposit is exploited by the Zapolyarny, senides of CoNiFe. Therefore, they are prob- Medvezhy Ruchei, and Ugol'ny Ruchei Mines; ably deposited in carbonate veins, whereas the the Talnakh deposit, Mayak, Komsomol'sky, and Skalisty mines; Taimyr (Oktyabr'sky), Asdepleted maucherite, Ni11As8, and niccolite, NiAs, are common in hydrothermally altered Oktyabr'sky and Komsomol'sky mines. peridotite, basic rocks, and metamorphosed The primary ores are composed of segrega- CuNi sulfide ores. tions of pyrrhotite and chalcopyritegroup Arsenide mineralization occurs in meta- minerals, cubanite and pentlandite (which are morphosed NiCu sulfide ores (Schneiderhö n, the result of solidstate modifications of Mss 1955; Yakovlev et al., 1981; Hytö nen, 1999; and Iss crystallized from sulfide melts) and 1 A new mineral ferroskutterudite and its name were approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association, October 24, 2006. The type ferroskutterudite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow. Registration number is 3440/1 Ferroskutterudite, Nickelskutterudite, and Skutterudite from the Norilsk Ore Field 17 magnetite. The composition of the primary chlorite and serpentinegroup minerals, carbon- ores ranges from pentlanditetroilitepyrrhotite ate, hydrogarnet, actinolite, grunerite, sela do - through pentlanditepyrrhotitecubanite and nite, ilvaite, diverse zeolites, apophyllite, xonot - pentlanditecubanitetalnakhite to pent- lite, pectolite, datolite, okenite and thaumasite. landitechalcopyrite (Godlevsky, 1959; Kula - The metamorphosed sulfide ores contain pyrite, gov, 1968; Genkin et al., 1981). During Nipyrite, valleriite, acicular bornite, millerite, postintrusion fluid conversion, magmatic sul- heazlewodite, chalcocite, mackinawite, hema- fides recrystallized and minerals of Pd, Pt, Au tite, ilvaite, violarite, godlevskite, cobaltpent- and Ag formed (Spiridonov et al., 2004). landite, tochilinite, vyalsovite, and arseni des and Areas of the East Siberian Platform are cov- antimonides of Ni and Co (Spiridonov et al., ered by thick sequences of basalt and tuff, and are 2000). Typical paragenetic associations of the intruded by numerous dolerite and gab- metamorphosed ores are Nipyrite + magnetite brodolerite plutons of the trap assemblage. The + valleriite, chalcopyrite + millerite + pyrite, trap assemblage and lower sequences were bornite + millerite, and chalcocite + heazle- affected by the 3generation regional metamor- woodite. Segregations of bornite are cut, over- phism. Generation1 involved the zeolite facies grown and replaced by segregations of chal- (Rb/Sr age estimated from apophyllite is 232 to cocite. 212 Ma), generation2, zeolite to prehnitepumpellyite facies (Rb/Sr age estimat- Antimonidearsenide mineralization ed from apophyllite and metabasalt as whole rock is of 212 to 196 Ma), and generation 3, high to Metamorphic hydrothermal impregnated lowtemperature part of the zeolite facies (Rb/Sr and vein mineralization is prominent in the age estimated from apophyllite is of 212 to 196 joint zones adjacent to tectonic faults, especial- Ma) (Spiridonov et al., 2000). The copperzeolite ly in the zone of the large NorilskKharaelakh assemblage, Ice land spar and zeolite deposits, fracture, as well as in sedimentary rocks agate and datolite mineralization, and barite, enriched in anhydrite and clay minerals. Ni, Co celestine, and (Zn, Pb, Cu, and Ag)sulfide occur- and Fe arsenides and Ni antimonides are dis- rences are related to this metamorphism (Fig. 1). seminated in metamorphosed CoNiCu sul- The Norilsk orebearing plutons and sulfide fide ores and form pods and impregnations in ores were also affected by lowgrade metamor- hydrothermal veins (Godlevsky, 1959; Kula - phism. Metadolerite contains prehnite, pumpel- gov, 1968; Dodin et al., 1971; Izoitko & Vyal' - lyite, epidote, albite, potassium feldspar, titanite, sov, 1973; Distler et al., 1975; Genkin et al., Fig. 1. Low grade meta- morphic generations and their isotopic age in the Norilsk region, East Siberian Platform. 18 New Data on Minerals. М., 2007. Volume 42 1981; Gritsenko & Spiri do nov, 2005a, 2005b, 9) with native arsenic and loellingite. 2006). The CoNiFe triarsenides were identi- The generation2 antimonidearsenide min- fied in the Norilsk ore field for the first time. eralization occurs in metamorphosed ores which The chloritecarbonate, carbonate (with are frequently enriched in chalcocite; native sil- prehnite and quartz), and apophyl- ver and bismuth, Hgrich silver, pyrargyrite, liteanhydritecarbonate veins with antimonides clausthalite and other selenides, and uraninite and arsenides occur at each deposit of the ore are characteristic minerals. Generation2 com- field. They are numerous at Talnakh, in the east- prises two assemblages: niccol- ern part of Oktyabrsky (Komsomolsky Mine), itebreithauptiterammelsbergiteloellingite and and in the southern part of Norilsk1 (Medvezhy Sbniccolitebreithauptite. Ruchei Mine). The veins of 0.3 to 150 cm thick The generation3 sul- and 0.1 to 15 m long. Calcite from the foarsenidesulfoantimonide mineralization (lat- arsenidebearing veins contains primary inclu- est assemblage) is associated with the pyrite and sions of NaClMgCl2 fluids with high salinity marcasitebearing metamorphosed ores. ranging from 6.5 to 12.6 wt % eq NaCl. Pressure The antimonidearsenide mineralization is and temperature of deposition estimated from enriched in Ni that correlates with the composi- these inclusions range 0.9 to 0.1 kb and from 216 tion of the Norilsk ores. Arsenides enriched in to 127°C. PT parameters of the arsenide mineral- Co periodically crystallized after deposition of ization correspond to those of zeolitefacies significant amount of Ni minerals. metamorphism. The isotopic age of apophyllite Arsenides and antimonides aggregates show from the arsenidebearing veins is 164 Ma, corre- us socalled geometric selection patterns, indi- sponding to the late generation of the burial cating crystallization from normal solutions in regional metamorphism (Spiridonov et al., 2002). open space. The calcite, calcitedolomite and apophyl- liteanhydritecarbonate veins with the NiCo Material and Research arsenides occur only within or adjacent to the metamorphosed deposits of CoNCu ores. The More than 100 samples from carbonate veins calcite and anhydritecalcite veins with native with arsenide mineralization from all deposits of arsenic and loellingite occur both within and the Norilsk ore field have been studied.