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Safyanovka |
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Russia |
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Cu Zn Au Ag
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Super Porphyry Cu and Au
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The Safyanovka (Saf'yanovka) massive and stringer-disseminated sulphide copper deposit is located in the Sverdlovsk area of the central Urals, 10 km ENE of the town of Rezh and 90 km NE of Yekaterinburg in the Russian Federation (#Location: 57° 23' 2"N, 61° 32' 2"E).
The reserves were originally estimated at 27.5 Mt @ 1.0 to 8.4% Cu. In 2000 the deposit was estimated to have contained 18.2 Mt @ 2.7% Cu, 1.47% Zn, with a further 7 Mt @ 3.2% Cu, 0.09% Zn as stringer ore, and 0.7 Mt @ 3.5 g/t Au, 50 g/t Ag in the gossan.
For details of the regional setting, see the Regional Setting section of the 50 Let Oktyabrya record.
Unlike most of the other VHMS deposits of the Urals Orogen, Safyanovka lies within the Rezh Zone of the East Uralian volcanic trough, which separates the Murzinka-Adul and Transuralian continental gneiss-schist blocks, and is regarded as a possible northward extension or thrust slice of the Magnitogorsk island-arc zone to the east of the Tagil arc. The Magnitogorsk arc comprises a Middle Devonian mineralised section and an Upper Devonian overlying volcanic sequences.
The host volcanic rocks to the Safyanovka deposit represent a packet of tectonic sheets, the uppermost sheet is composed of the Rezh ultramafic massif while the para-autochthonous basement consists of Visean platformal limestone and coal-bearing shales. These two elements are separated by the following units (from older to younger):
• Early Eifelian basic rocks of ophiolitic association;
• Early Eifelian ore-bearing rhyolite and dacite;
• Givetian andesite-dacite volcanic sequence and limestone;
• Frasman tuff of basaltic andesite and Famennian and Tournaisian trachyte-basalt association.
Subsequent thrusting has resulted in the younger rocks commonly having been overthrusted by older rocks.
The Early Eifelian ophiolitic association forms the uppermost tectonic sheet, with an uppermost section of sheared serpentinized harzburgite and chloriteactinolite schists, gabbro and parallel diabase dykes. Tholeiitic aphyric volcanics and phtanite interlayers are prevalent in the lower part.
The Early Eifelian ore-bearing complex of silicic volcanics forms the lower section of the middle tectonic sheet, the upper boundary of which is traced by unevenly hematised andesitic tuff belonging to the overlying andesite-dacite sequence and mostly coincides with a thrust fault. The thrust zone is characterised by an intricate imbricated structure, with silicic volcanics coming into contact with spilite, gabbro, Givetian limestone and Famennian trachybasaltic tephroids. The lower boundary is also represented by a thrust fault with lenses consisting of serpentinite, Visean carbonaceous shale, limestone and Frasnian basaltic andesitic tuff transposed into the mylonite.
Flow-banded lava, extrusive and domal breccias, and tuff of tholelitic dacite occur in the lower part of the silicic volcanics. They are overlain by tephrolds of the same composition, tuffite and chert section up to 400 m thick. The rhythmically bedded volcanoclastic rocks are overlain and intercalate with concordant layers and lenses of welded unsorted pyroclastic material and rhyolitic clasto-lava with small quartz phenocrysts. Boundaries between the coarse juvenile pyroclastic rocks and thin-bedded tephroids related to periods of waning silicic volcanism serve as a guide for localisation of colloform massive sulphide ore.
The hangingwall section of the silicic volcanics is largekly composed of fine clastic rocks with interbands of chert and cherty tuffite. The bedded hangingwall and ore hosts are intruded by poorly altered sill-like subvolcanic rhyolite porphyry with abundant large quartz phenocrysts. The porphyry is locally constitutes the immediate hangingwall to the massive ore.
The Early Givetian Upper Safyanovka andesite-dacite complex is >600 m thick and comprises red-colored altered agglomerate of unsorted and bedded andesitic, dacitic and rhyolitic tuffs, which overlie the orebearing Eifelian silicic volcanics.
The Frasnian basalt and basaltic andesite of the Boroukha Complex occurs as two thick tectonic sheets, one of which underlies the ore-bearing silicic pyroclasts, while the other overlies the orebearing unit in the north. The Boroukha Complex comprises a lower sequence of bedded volcanomictic gritstone, tuffaccous sandstone, and claystone. Fragments of basaltic greenstone, aphyric spilite, limestone, felsic rocks, and quartz xenocrysts indicate that the tholeiltic and andesite-dacite complexes were eroded. The Famennian to Tournaisian Upper Boroukha complex comprises subalkaIine basalts, associated with flyschoid graywacke as tuffaceous lenses, lava flows, and sparse dykes.
Intrusive rocks are not abundant in the ore field.
The Safyanovka deposit is situated within a remnant alpine-type nappe, composed of several tectonic sheets, with the sheets of relatively younger volcanic and sedimentary rocks overthrust by older rocks. The lower allochthonous sheet, consisting of Frasnian-Famennian basaltic rocks, is overlain by mineralised silicic volcanics of Early Eifelian, Givetian limestone, andesite (middle sheet), and then by the older ophiolites.
The ore-bearing sheet is plate-shaped and distinctly stratified. Mineralisation is virtually confined to this sheet and does not extend beyond its limits. Within the ore field, the basal thrust fault defining the base of the sheet, dips southwestward at an angle of 20 to 25° and is embraced by a zone of shearing amd mylonite development with lenses of chlorite-antigorite schist. The roof of ore-bearing sheet is limited by a more complicated wave-like surface with thick infolded lenses of spilite and ultramafics reducing the thickness of silicic pyroclastic rocks from 450 to 150 m.
The internal structure of the ore-bearing sheet is disrupted by numerous shear zones oriented parallel to the stratification and lesser oblique offsetting structures with relatively minor displacement.
In the southern part of deposit the massive sulphide ore extends as a discontinuous chain of lenticular lodes varying in thickness from 30 to 50 cm, up to a few tens of metres, which are concordant to the bedding of the altered hosts. The lodes are readily traced along the strike and gently plunge to the south at an angle of 20 to 25°, although they pinch out sharply across the strike. Three main stratigraphic levels of massive ore are recognised.
The major mass of massive sulphide and high-grade disseminated ores is confined to the northern part of ore field where they are mined by open pit. The massive ore forms a thick wedge-shaped lode, composed of up to six isolated orebodies separated by mineralised altered rocks and rhyolite dikes.
A considerable portion of ore reserves are represented by stockwork pyrite-chalcopyrite ore shoots, which are localised between the middle and lower levels massive sulphide ore lenses. Within the high-grade ore zone, chalcopyrite veinlets cut both previously mineralised pyroclastic rocks and brecciated subvolcanic rhyolite similar to the hangingwall porphyry.
Stockwork, massive sulphide, disseminated and higfh grade lodes have been recognised at Safyanovka. The stockwork copper ore is represented by a network of chalcopyritc-pyrite veinlets hosted in altered volcanics. The massive sulphide ore is subdivided into zinc-copper, copper and pyrite varieties. Massive, banded, breccia-like ores with granular, colloform and interstitial textures are also recognised. The disseminated zinc-copper ores occur peripheral to the massive sulphide lodes and are distinguished by a higher degree of crystallisation, lower Fe content in sphalerite and the presence of free gold.
Ore shoots are located at the boundary between massive and stockwork ores of the Northern lode. In general, they follow the Western synvolcanic fault and dip steeply eastward. The thickness of individual shoots varies from <1 m to 20 m. They mainly comprise chalcopyrite and are surrounded by a haloes of chalcopyrite veinlets and associated chlorite alteration. Pyrite occurs in a much lesser amount and forms spectacular porphyroblasts, up to 3 cm across. Tellurides and other rare minerals are also present.
The most recent source geological information used to prepare this decription was dated: 2000.
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.
Saf'yanovka
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Selected References:
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Maslennikov V, Koroteev V, Prokin V, Yazeva R, Bochkarev V and Fershtater G, 2000 - Massive sulfide deposits of the Central and Southern Urals: in Seltmann R, Koroteev V, Fershtater G and Smirnov V, 2000 The Eroded Uralian Paleozoic Ocean to Continent Transition Zone; Granitoids and Related Ore Deposits IUGS/UNESCO, IGCP Project 373, International Field Conference in the Urals, Russia, 18-30 July, 2000, Excursion Guidebook, Publication #14, IGCP Project 373, Natural History Museum, London, pp 69-98
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Maslennikov, V.V., Ayupova, N.R., Safina, N.P., Tseluyko, A.S., Melekestseva, I.Yu., Large, R.R., Herrington, R.J., Kotlyarov, V.A., Blinov, I.A., Maslennikova, S.P. and Tessalina, S.G., 2019 - Mineralogical Features of Ore Diagenites in the Urals Massive Sulfide Deposits, Russia: in Minerals (MDPI) v.9, 38p. doi:10.3390/min9030150.
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Safina, N.P., Melekestseva, I.Yu., Nimis, P., Ankusheva, N.N., Yuminov, A.M., Kotlyarov, V.A. and Sadykov, S.A., 2016 - Barite from the Safyanovka VMS deposit (Central Urals) and Semenov-1 and Semenov-3 hydrothermal sulfide fields (Mid-Atlantic Ridge): a comparative analysis of formation conditions: in Mineralium Deposita v.51, pp. 491-507
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Vikentyev, I.V., Belogub, E.V., Novoselov, K.A. and Moloshag, V.P., 2017 - Metamorphism of volcanogenic massive sulphide deposits in the Urals. Ore geology: in Ore Geology Reviews v.85, pp. 30-63.
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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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