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Yenisey Ridge District - Olympiada, Titimukhta, Panimba, Verduginskoe / Verduga |
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Siberia - Krasnoyarsk, Russia |
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Au
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Yenisey Ridge is located along the south-western margin of the Siberian Craton, east of the Yenisey River. It hosts an important belt of Au and Au-Sb deposits which are distributed over a NNW-trending interval of 200 km. The most significant of these is the Olympiada Mine and is located 600 km north from Krasnoyarsk in the Severoeniseysk area of Krasnoyarsk region, 80 km from the city of Severoeniseysky (#location: Olympiada - 59° 51' 51"N, 92° 55' 0"E).
Other deposits along the ridge include Titimukhta, Veduga, Sovetskoe, Udereiskoe, Sergeevskoe, Eldorado, Aleksandro-Ageevskoe, Proletarskoe, Gerfed, Panimba and Razdolninskoye.
Historic production from the Yenisey Ridge region since 1832 has been >500 t of Au, mainly from alluvials. Bedrock mining of the shear zone hosted quartz vein complexes commenced in 1898. Cretaceous-Palaeogene weathering, variably down to 300 m in deep fault zones, has led to secondary enrichment of gold.
Olympiada
The Olympiada gold deposit had pre-production reserves of some 550 to 600 tonnes of contained Au, with approximately 415 tonnes remaining at an average grade of 3 to 4 g/t Au in primary disseminated sulphide mineralisation, and ~10 g/t Au in supergene ores in the 16 Mt of oxide saprolitic sand ore so far defined. The deposit is located in the Yenisei Ridge terrane which is composed of Palaeoproterozoic to Upper Neoproterozoic (Riphean) to Lower Palaeozoic metasedimentary and igneous rocks, metamorphosed to amphibole and amphibole-epidote greenschist facies.
The Olympiada deposit area is underlain by metasedimentary clastic-carbonate, locally carbonaceous, rocks which occur as a large roof pendant within a surrounding and probably underlying, Neoproterozoic granitoid batholith complex. Bodies of disseminated mineralisation occur in zones of high strain and extensive rock alteration within black argillites, localised at the contact zone between quartz-mica and carbonate-quartz-mica schists, controlled by a district-scale anticline (which incorporates bedding-subparallel fractures) and its intersection with transverse fault zones.
Several orebodies are known, the largest of which accounts for about 90% of the reserves, being about 130 to 170 m thick, up to 400 m long and localised in the fold closure. The latter can be subdivided into two 'branches', extending for 520 m and 320 m along strike respectively, which can be traced down the steep (60 to 80°) plunge for at least 800 m. The orebodies are characterised by carbonate-quartz-mica alteration containing 3 to 5% sulphides (mostly arsenopyrite, pyrite, pyrrhotite and stibnite) and scheelite. Very minor chalcopyrite, sphalerite, galena, tennantite-tetrahedrite and Bi-minerals are present locally. Gold occurs in a dispersed form in sulphides (arsenopyrite and pyrite) and as free native gold, with a fineness of 910 to 990 in early (pyrite-arsenopyrite) and 650 to 750 in late (stibnite) assemblages. Arsenopyrite contains up to 2100 g/t Au (Genkin et al., 2002). The oxidised (supergene) ore occurs to a depth of 120 to 300 m below the surface and is composed of a soft micaceous sandy-clay mixture, corresponding to the Cretaceous-Paleogene palaeoregolith. It contains up to 10% sulphides and is dominated by native gold, with local bonanza grades of up to 450 g/t Au.
The supergene oxide ores are represented by loose, multicolored argillaceous-silt saprolites representing linear weathering crusts of Cretaceous to Palaeogene age that occur along folded zones of contacts between ore-bearing clastic and carbonaceous-clastic sequences. Gold occurs in a free metallic form that is easy to extract.
Remaining mineral resources at the Olympiada deposit in 2010 were (Polyus Gold website):
Measured resources - 19.3 Mt @ 5.0 g/t Au;
Indicated resources - 79.8 Mt @ 3.70 g/t Au;
Indicated resources - 37.2 Mt @ 3.10 g/t Au;
for a combined 510 tonnes of contained gold.
Remaining JORC compliant Ore Reserves and Mineral Resources at 31 December 2017 were (Polyus Ore Reserves and Mineral Resources Update 20 March, 2018):
Proved + Probable Ore Reserves - 295 Mt @ 2.9 g/t Au for 855 t of contained gold;
Measured Mineral Resources - 6.5 Mt @ 2.9 g/t Au;
Indicateded Mineral Resources - 320 Mt @ 3.0 g/t Au;
Inferred Mineral Resources - 127 Mt @ 2.8 g/t Au;
TOTAL Mineral Resources - 454 Mt @ 3.0 g/t Au for 1362 t of contained gold;
Titimukhta
The satellite Titimukhta gold deposit is located 9 km north-west of Olympiada, also on the Yenisey Ridge. The deposit is hosted by a sequence of relatively homogenous quartz-biotite schist. Black shales, similar to those found at Olympiada lie to the east, and granite gneiss to the west and north-west of the deposit. The distribution of mineralisation is controlled by the black shale and granite as well as flanking faults to the east and west. The principal units dip steeply east, to new vertical. The deposit area is characterised by a zone of intense faulting, with major NW-SE trending structures along the northern side of the deposit. In the mineralised zone, the host rocks have a very high silica content with a strong development of narrow quartz veinlets, as well as a few large quartz veins that are up to 1.5 m thick at surface. The main zone of mineralisation is up to 550 x 350 m in an area at surface elongated north-south. It comprises a stockwork of mineralised quartz veins in a schistose host rock. Gold mineralisation extends to a depth of 500 m and that occurs as stacked zone that dip at 30 to 35°E, crosscutting stratigraphy.
The mineralised veins are a complex combination of quartz, quartz-carbonate and quartz-feldspar, and can be up to 1 m thick, but average 0.2 two m. Sulphide mineralisation totals 1.1 to 2.1% and comprises pyrite, minor pyrrhotite, and less common galena, chalcopyrite and molybdenite. Arsenopyrite is present in very small amounts. Four major gold associations haven't been recognised: i). gold between quartz crystals (36%); ii). within bismuth (48%); iii). associated with sulphide minerals (9%); and iv). associated with titanium minerals, mica and feldspar (7%). There has only been limited weathering of being rock to a depth of ~30 m and that no significant oxide mineralisation has been developed.
Remaining JORC compliant Ore Reserves and Mineral Resources at 31 December 2017 were (Polyus Ore Reserves and Mineral Resources Update 20 March, 2018):
Proved + Probable Ore Reserves - 12 Mt @ 2.3 g/t Au for 29 t of contained gold;
TOTAL Mineral Resources - 12 Mt @ 2.4 g/t Au for 29 t of contained gold;
Panimba
The Panimba gold prospect is located ~36 km SE of Olympiada. It occurs in an area of complex folding in which five distinct memorised zones have been recognised. Two of these, the Mikhailovsky and Zolotoye zones are the most significant.
The Mikhailovsky Zone is subdivided into three separate orebodies that are predominantly composed on mylonitised and cataclastic, finely modular, strongly silicified, carbonaceous-quartz-sericite schist with up to 10% sulphides. Mineralisation is mainly disseminated, although thin (1 to 15 mm) sinuous quartz stringers are also present. These stringers commonly contain sulphide mineralisation composed of pyrite, pyrrhotite and arsenopyrite with finely disseminated gold. The ore zones tend to be sinuous with variable strike lengths, that vary from tens to hundreds of metres, and thicknesses of up to 50 m. Grades vary from 2 to 3.5 g/t Au.
The Zolotoye Zone is a complex of crosscutting quartz veins and stringers that follow the main structural trends and has the form of a linear stockwork which persists to a depth of >600 m. it is composed of six ore zones and at least 33 lenses.
JORC compliant Mineral Resources at 31 December 2017 were (Polyus Ore Reserves and Mineral Resources Update 20 March, 2018):
TOTAL Mineral Resources - 40 Mt @ 2.0 g/t Au for 80 t of contained gold;
Details of Titimukhta and Panimba deposits are drawn from the "Competant Person's Report - Mineral Assets PJSC Polyus, prepared by AMC Consultants Pty Ltd, Perth, Western Australia, dated 5 June 2017".
The most recent source geological information used to prepare this decription was dated: 2017.
Record last updated: 7/6/2019
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.
Olympiada
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Selected References:
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Genkin A D, Bortnikov N S, Cabri L J, Wagner F E, Stanley C J, Safonov Y G, McMahon G, Friedl J, Kerzin A L, Gamyanin G N 1998 - A multidisciplinary study of invisible Gold in arsenopyrite from four mesothermal Gold deposits in Siberia, Russian Federation: in Econ. Geol. v93 pp 463-487
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Seltmann, R., Soloviev, R., Shatov, V., Pirajno, F., Naumov, E. and Cherkasov, S., 2010 - Metallogeny of Siberia: tectonic, geologic and metallogenic settings of selected significant deposits: in Australian J. of Earth Sciences v.57, pp. 655-706.
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Tomilenko A, Gibsher N, Dublyansky Y and Dallai L, 2010 - Geochemical and Isotopic Properties of Fluids from Gold-Bearing and Barren Quartz Veins of the Sovetskoye Gold Deposit (Siberia, Russia) : in Econ. Geol. v105 pp. 375-394
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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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