Korbalikha and Rubtzovskoe
Zn Cu Pb
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The Korbalikha and the nearby Rubtzovskoe Zn-Cu-Pb deposits are located in the Altai region of south-west Siberia, Russia, ~150 km NW of Ridder in Kazakhstan. Rubtzovskoe is 20 km east of the city of Rubtzovsk (#Location: 51° 10' 48"N, 82° 13' 12"E).
The Altai region of Russian Siberia, is the northwestern extension of the Rudny Altai VHMS metallogenic province of eastern Kazakhstan. Both provinces are hosted by a volcano-plutonic belt related to a Devonian island arc, which was established over the clastic-carbonate basement rocks of a passive Ordovician to Silurian continental margin.
The host Devonian succession tests on a Neoproterozoic to Cambro-Ordovician basement is composed of a 4500 to 5000 m thick bimodal basalt-rhyolite suite accompanied by volcanic-hosted polymetallic (Cu-Pb-Zn) and Ba-polymetallic deposits formed in submarine conditions. Hydrothermal-metasomatic processes are also evident along the conduits of ascending fluids in an environment of weakly-lithified sediments. Relatively early VHMS mineralisation, mostly associated with rhyolitic suites, is characterised by Ba-Pb-Zn, with elevated Au and Ag contents, whereas younger rhyolite-dacite and basalt-andesite volcanic rocks host ore rich in Cu-Zn-Pb (e.g., Eremin and Dergachov, 1998; Distanov et al., 2006).
The Korbalikha deposit is hosted within Middle to Upper Devonian clastic rocks and volcano-sedimentary sequences. The latter are subdivided into five units, composed of rhyolite and rhyodacite tuffs, tuffaceous sandstones, andesite-basalt lavas by Late Palaeozoic gabbroic dykes.
The structure of the deposit is characterised by the combination of small folds and variously-oriented normal and thrust faults.
Sulphide mineralisation is found throughout the entire volcano-sedimentary sequence, although the major economic orebodies are only associated with the Upper Devonian tuffaceous sandstone unit. The ores are accompanied by both chloritic and quartz-sericite alteration, and comprises a sphalerite-chalcopyrite-pyrite assemblage, with minor sphalerite-pyrite, sphalerite-galena and barite-galena.
A distinct mineral zonation is represented by the transition from i). barite-Pb-Zn, to ii). massive pyrite with Pb-Zn sulphides, and iii). Cu sulphide-pyrite dominant assemblages in the upper, central and lower parts of the deposit respectively.
The orebodies has a strike length of up to 1000 m, and have been traced to depths of 750 m.
Reserves in 2009 were:
28 Mt @ 1.17% Cu, 1.66% Pb and 7.86% Zn,
for contained tonnages of 328 100 t of Cu, 466 400 t of Pb and 2.2 Mt of Zn.
The Rubtzovskoe Zn-Pb-Cu deposit is smaller but higher grades than Korbalikha. It is hosted within a volcano-sedimentary sequence that includes Middle Devonian siltstones, overlain by Upper Devonian volcanogenic rocks. The Middle to Upper Devonian volcano-sedimentary sequence includes rhyolitic lava, flow breccia and tuffs of the Davydov Formation. The rhyolite is overlain by 30 to 100 m of Upper Devonian Kamenavka sub-formation, comprising clayey-, calcareous-, cherty- carbonaceous siltstones, arkoses cherty argillite, arkosic sandstone, siltstone and rare interbeds of tuffs and limestone. The ore is hosted within the Kamenavka sub-formation. Late Devonian subvolcanic rhyolitic and rhyodacitic porphyritic intrusives intrude the Middle to Upper Devonian volcano-sedimentary sequence, and are localised in the deposit area (Chinakov and Balyaev, 1973; Stroitelev et al., 1996; Chekalin, 2002).
The host succession is overthrust by a Lower Carboniferous succession, comprising a lower sequence of conglomerate, grits and polymictic sandstone, passing upwards into limestone and carbonaceous siltstone. All of these rocks are overlain by thick (80 to 100 m) Neogene to Quaternary clay dominated sediments.
Mineralisation is hosted by Upper Devonian clastic rocks in the lower sections of the Kamenavka sub-formation, and occurs as a single, lens-like, orebody outcropping at the surface, extending to a depth of 100 to 215 m below the surface, with a strike length of ~800 m. The deposit is confined to the northern limb of a gentle syncline. Wallrock alteration affects both the volcanoc rocks of the Davydov Formation and the host Kamenavka sub-formation, with a downward zonation from albite, to chlorite-carbonate-sericite-quartz to sericite-quartz.
The ore body is composed of massive, veinlet-disseminated and mylonitised (brecciated) Pb-Zn sulphides, lesser Cu sulphide, pyrite and Cu-Zn-Pb ores. The massive ores form a major part of the orebody, passing into veinlet-disseminated ores toward its flanks and into the footwall, where they form a steeply dipping sulphide stockwork. Brecciated mineralisation occurs in fault zones crosscutting the orebody.
Major ore minerals include sphalerite, galena, pyrite and chalcopyrite, with minor tennantite and barite. Pyrite-sphalerite constitutes the most abundant ore assemblage, with chalcopyrite-pyrite-galena occurring as veinlets in the pyrite-sphalerite mineralisation.
Reserves in 2009 were:
2.425 Mt @ 4.5% Cu, 6.5% Pb, 12% Zn, 145 g/t Ag and 0.74 g/t Au (containing 1.8 t Au and 351 t Ag).
Other deposits in the Rubtzovskoe district include Stepnoe, Talovskoe and Zakharovskoe.
The information for this summary is largely derived from: Seltmann R, Solovieva R, Shatov V, Pirajnoa F, Naumov E and Cherkasov S, 2010 - Metallogeny of Siberia: tectonic, geologic and metallogenic settings of selected significant deposits: in Australian Journal of Earth Sciences, v.57 pp. 655-706.
The most recent source geological information used to prepare this summary was dated: 2010.
This description is a summary from published sources, the chief of which are listed below.
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