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Kalinovskoe, Tomino, Birgilda, Michurino, Biksizak |
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Chelyabinsk Oblast, Russia |
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Cu Au Zn
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Super Porphyry Cu and Au
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The Kalinovskoe and Tomino porphyry copper-gold deposits are located ~200 km north of the similar Mikheevskoe deposit and 20 to 40 km SE of Chelyabinsk in the Uralian Fold Belt (or Uralides) of the Urals Mountains in the Russian Federation.
Regional Setting
For an outline of the setting of the Uralides, see the Mikheevskoe record.
The Kalinovskoe and Tomino Cu-porphyry deposits are members of the Birgilda-Tomino ore cluster, which is located within the East Uralian Volcanic Megaterrane.
The Birgilda-Tomino cluster forms a north-trending mineralised corridor that is 20 to 25 km wide and ~40 km long (Plotinskaya et al., 2014, 2016 and references cited therein). The northern and eastern parts of this corridor are composed of Early to Middle Ordovician basalts of the Sargazy Formation which have a maximum thickness of 1.5 km and is accompanied by co-magmatic gabbro-diorite-plagiogranite intrusions of the Middle-Late Ordovician Voznesenka Complex. Both the volcanic and intrusive rocks have a bimodal (felsic-mafic) composition (Grabezhev et al., 1998). The basalts are succeeded by Middle Ordovician to Upper Devonian sedimentary rocks of with a total thickness of >1 km. The central and southwestern parts of the area are masked by Late Devonian to Early Carboniferous volcanic andesitic and dacitic volcanic and sedimentary rocks of the Bereznyakovskoe Formation that are up to 1 km thick. Numerous diorite porphyry stocks of the Birgilda-Tomino Igneous Complex intrude both the basalt and andesite-dacite rocks. These are co-magmatic with the Bereznyakovskoe Formation (Grabezhev et al., 1998; Puzhakov, 1999). The Birgilda-Tomino Igneous Complex principally occurs as three main irregularly shaped intrusive bodies, hosting the North Tomino, Tomino, and Kalinovskoe porphyry copper deposits. To the SW of the corridor, Late Carboniferous andesite tuffs follow the Bereznyakovskoe Formation above an angular unconformity. All of the igneous rocks of the region are overprinted by pervasive propylitic alteration. Granite and granodiorite of the composite Early Carboniferous to Late Permian Chelyabinsk pluton are exposed in the north of the area (Grabezhev et al., 1998).
Ordovician aphyric basaltic lavas and tuffs occur at the base of the exposed country rock section and host the Kalinovskoe, Tomino and Birgil'da porphyry
copper deposits.
The Birgil'da-Tomino ore cluster also includes a variety of Late Palaeozoic high- and low sulphidation Au-Ag epithermal deposits (e.g., Bereznyakovskoe Au-Ag and Michurino Cu-Ag-Pb-Zn), and skarn-related base metal mineralisation (e.g., Biksizak Zn-Pb-Cu-Ag) in carbonate rocks.
Together, the Tomino and Kalinovskoe deposits, which comprise the Tomino ore field, had total reserves of 331 Mt at 0.46% Cu and 0.1 g/t Au (Volchkov et al., 2015). Plotinskaya et al. (2014) quote inferred resources within the district as containing: 2.8 Mt of Cu, mainly in porphyry deposits; 1.7 Mt of Zn in the epithermal and carbonate hosted mineralisation and 36 t of contained Au, mainly in epithermal deposits. Plotinskaya et al. (2019) quotes the Tomino ore field deposits as containing 660 Mt @ 0.4% Cu (after the Russian Copper Company, 2019).
Geology and Mineralisation
Porphyry copper mineralisation at Kalinovskoe and Tomino is confined to two irregularly shaped quartz diorite porphyry stocks, each covering an area of 2 to 3 km2. The northern stock hosts the Tomino mineralised centre, while the southern contains Kalinovskoe. The Kalinovskoe stock comprises three main phases: a i). seriate diorite porphyry, ii). quartz-diorite porphyry and iii). equigranular microdiorite porphyry. It belongs to a K-Na calc-alkaline series intrusion which is part of the Birgil'da-Tomino Igneous Complex which have been dated at 428 ±3 Ma and 427 ±6 Ma in the Mid Silurian (U-Pb zircon; Grabezhev et al., 2013). Molybdenite from Kalinovskoe deposit has been dated at 430.4 ±2.0 Ma (Re-Os; Tessalina and Plotinskaya 2017; Plotinskaya et al., 2018).
The diorite porphyries are intruded into basalts of the Ordovician Sargazy Formation. Relationships between the three intrusive phases are uncertain as most are pervasively altered with only relics of former porphyry textures preserved. Small plagiogranite xenoliths of the Voznesenka Igneous Complex are common. No textures or crosscutting relationships of mineralised veins and porphyries allows the association of mineralisation with a single phase of porphyry intrusion.
Veinlet-disseminated mineralisation is largely restricted to the eastern part of the diorite stock and occurs both in the diorite porphyries and surrounding basalts, and is mostly composed of chalcopyrite, pyrite, molybdenite and minor bornite. The central core of the deposit is characterised by phyllic quartz-sericite alteration with associated chalcopyrite, molybdenite and minor bornite, surrounded by peripheral propylitic (chlorite, epidote, carbonate) alteration containing pyrite-chalcopyrite mineralisation. Bismuth-gold-(base metal) mineralisation forms an epithermal overprint on the earlier stages. Potassic biotite-sericite alteration is only found as small relics within the phyllic aureole and appears to be completely replaced by the later alteration stages. Albitisation occurs in the periphery of the diorite stock, where it is manifested by up to 1 cm thick albite veinlets with 1 to 3 cm wide alteration halos in propylitic diorite.
Light-grey, up to 2 to 3 cm thick quartz veinlets are found in the central core of the deposit, spatially associated with phyllic alteration. They are A-type veins (after Gustafson and Hunt, 1975) and contain chalcopyrite and minor bornite, and in places carbonate. Molybdenite stringers are relatively rare and often confined to the same veinlets, but typically show cross-cutting relationships with quartz, suggesting B-type affinity although such veinlets are not typical of porphyry systems associated with calc-alkaline intrusions (Sillitoe, 2010). Molybdenite, whilst rare, but can be found throughout the deposit, mainly within the zone of phyllic alteration. It occurs as disseminations, nests and veinlets. The nests are often overgrown and brecciaed by later chalcopyrite. Whilst there is no published data (to 2017) on Mo content or Cu/Mo ratio at Kalinovskoe, the neighboring Tomino deposit has Cu/Mo ratio from 100 to 300, occasionally 25 to 50 (Grabezhev, 2013). The central core of the Kalinovskoe deposit has elevated Re contents in molybdenite of up to 0.95 wt.% in a single point analysis, but is normally below 0.15 wt.% (Plotinskaya et al., 2014). The Tomino deposit has Re contents ranging from 0.05 to 0.4 wt.% (Grabezhev and Hiller, 2015).
Mineralisation associated with propylitic alteration includes several generations of abundant disseminations and veinlets. The veinlets comprise 1 to 6 cm thick grey porous quartz, that occur throughout the deposit, and are characterised by epidote, carbonate and chlorite, with abundant pores, most likely the result of dissolution of calcite or anhydrite. These may host rare nest-like accumulations of chalcopyrite and crosscut albitised zones. Pinkish quartz veins up to 5 to 7 cm thick, cut porous quartz veins. They are associated with chalcopyrite and are cut by chlorite stringers. Magnetite and specular hematite are present as rare disseminations, mostly in the periphery of the deposit, but may also occur in quartz-carbonate veinlets, and are overprinted by pyrite-chalcopyrite stringers. Abundant disseminations, veinlets, and stringers of pyrite-chalcopyrite-chlorite-epidote, locally with carbonate, tourmaline and K-Na white mica, are found in the peripheral propylitic alteration zone. Locally, quartz-sericite-pyrite phyllic alteration forms zones up to several metres wide within the propylitic-altered basalts and contain only small veinlets of milky-white quartz with pyrite. These veins are interpreted to have developed after rhyolitic interlayers and formed simultaneously with the propylitic alteration. The youngest generation of veinlets cutting earlier minerals comprises a bismuth-gold-base metal stage. Gangue minerals are calcite and quartz with variable bismuth sulphosalts, electrum and rare tetrahedrite and sphalerite. Studies of tourmaline from phyllic and propylitic alteration (Baksheev et al., 2012) indicates early schorl-oxyschorl typical of propylites at porphyry copper deposits, overgrown by intermediate members of the dravite-magnesiofoitite solid solution series typical for epithermal deposits, suggesting a telescoped epithermal overlap at the Kalinovskoe copper porphyry mineralisation (Plotinskaya et al., 2014).
The high sulphidation Bereznyakovskoe Au-Ag deposit has been described in a separate record.
The Michurino epithermal mineralisation, which is ~10 km NW of the Kalinovskoe porphyry deposit, is hosted by tuffs, tuff breccias, and andesite-dacite lavas of the Bereznyakovskoe Formation, intruded by co-magmatic subvolcanic andesites. The host rocks have been subjected to sericitic, chloritic and argillic alteration, although primary porphyry textures are still recognisable. Locally the host rocks are pervasively altered to quartz-clay-sericite with disseminated pyrite. Quartz veinlets with intense associated disseminated pyrite are part of the quartz-pyrite stage, with pyrite also occurring as small accumulations, or, locally, massive aggregates of pentagonal crystals. Chalcopyrite, bornite and rarely colusite fill pores and cracks within pyrite crystals. Quartz-pyrite veining is cut by 1 to 2, up to 10 to 20 cm thick dolomite veinlets containing pyrite, chalcopyrite, tetrahedrite-tennantite, galena and sphalerite. Native gold is found as small isometric grains, no larger than 5 µm across, intimately intergrown with galena, tetrahedrite-tennantite, or chalcopyrite, which appear to be part of the same assemblage. Telluride minerals include hessite, petzite, tellurobismuthite, with minor volynskite and tetradymite, filling cracks and pores in the sulphides, and may represent a later generation, although no clear cross-cutting relationships have been observed. Veinlets of pale pink quartz with minor calcite crosscut earlier stages and represent a post-ore stage (Plotinskaya et al., 2014).
The Biksizak Zn-Pb-Cu-Ag mineralisation is located ~5 km north of Michurino. Mineralization contains up to 28% Zn, up to 1% Cu, tens to thousands
ppm Pb, traces to 3 ppm Au, and to 157 ppm Ag (Puzhakov, 1999; Plotinskaya et al., 2010). The deposit is divided into a West and an East zone, differentiated by ore mineralogy and ore geochemistry (Grabezhev et al., 1998; Snachev and Kuznetsov, 2009; Seravkin and Snachev, 2012). The West zone zone is restricted to a limestone lens in andesite-dacite tuffs of the Bereznyakovskoe Formation, whilst the East zone forms a series of interlayers, at the top
of limestone suite of the Biksizak Formation. In addition, uneconomic porphyry mineralisation comprising pyrite and rare chalcopyrite and molybdenite within a diorite intrusion occurs in the westernmost part of this deposit area (Puzhakov, 1999). Mineralised interlayers are up to several metres thick, separated by barren intervals up to 10 m thick. Ore in both zones is conformable with the limestone beds and comprise disseminations, stockworks and, locally, massive sulphides. Limestone wall rocks are altered to ankerite-dolomite, whereas within the mineralised beds, the carbonate rocks are altered to ankerite-dolomite and silica. Within the Eastern zone, limestone adjacent to the contact with porphyritic diorite, is altered to a chlorite-epidote-carbonate-rutile skarn-like assemblage, which was probably formed by the breakdown of garnet during retrograde alteration processes. Five spatially separated ore mineral assemblages have been identified: i). hematite-magnetite; ii). pyrite-arsenopyrite; iii). chalcopyrite-sphalerite; iv). tennantite-tetrahedrite-chalcopyrite; and v). silver sulphosalts (Plotinskaya et al., 2010).
The most recent source geological information used to prepare this decription was dated: 2019.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Hammarstrom, J.M., Mihalasky, M.J., Ludington, S., Phillips, J.D., Berger, B.R., Denning, P.D., Dicken, C.L., Mars, J.C., Zientek, M.L., Herrington, R.J. and Seltmann, R., 2017 - Undiscovered porphyry copper resources in the Urals - A probabilistic mineral resource assessment: in Ore Geology Reviews v.85, pp. 181-203.
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Plotinskaya, O.Y., Abramova, V.D., Groznova, E.O., Tessalina, S.G., Seltmann, R.; and Spratt, J., 2018 - Trace-element geochemistry of molybdenite from porphyry Cu deposits of the Birgilda-Tomino ore cluster (South Urals, Russia): in Mineralogical Magazine v.82, pp. S281-S306.
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Plotinskaya, O.Yu., Abramova, V.D., Bondar, D., Seltmann, R. and Spratt, J., 2019 - Porphyry Cu(Mo) deposits of the Urals: insights from molybdenite trace element geochemistry: in Life with Ore Deposits on Earth, LODE 19, Magmatic hydrothermal systems: from Porphyry to Epithermal, 15th SGA Biennial Meeting, 27-30 August, 2019, Glasgow, Scotland, Proceeding v.2, pp. 1019-1022.
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Plotinskaya, O.Yu., Chugaev, A.V. and Seltmann, R., 2017 - Lead isotope systematics of porphyry-epithermal spectrum of the Birgilda-Tomino ore cluster in the South Urals, Russia: in Ore Geology Reviews v.85, pp. 204-215.
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Plotinskaya, O.Yu., Grabezhev, A.I., Groznova, E.O., Seltmann, R. and Lehmann, B., 2014 - The Late Paleozoic porphyry-epithermal spectrum of the Birgilda-Tomino ore cluster in the South Urals, Russia: in J. of Asian Earth Sciences v.79, pp. 910-931.
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Plotinskaya, O.Yu., Grabezhev, A.I., Tessalina, S., Seltmann, R., Groznova, E.O. and Abramov, S.S., 2017 - Porphyry deposits of the Urals: Geological framework and metallogeny: in Ore Geology Reviews v.85, pp. 153-173.
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Tessalina, S.G. and Plotinskaya, O.Yu. 2017 - Silurian to Carboniferous Re-Os molybdenite ages of the Kalinovskoe, Mikheevskoe and Talitsa Cu- and Mo porphyry deposits in the Urals: Implications for geodynamic setting: in Ore Geology Reviews v.85 pp. 174-180.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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