Other Names: Aldan, Aldanzoloto, Aldgold
District: Amur Region
Commodities : Gold
Kuranakh gold deposit is located in the Central Aldan Ore district of the Archean Aldan shield on the southern flank of the Siberian Platform. The Aldan shield consists of gneisses, granulites and granites that have been metamorphosed to granulite and amphibolite facies. N- and NE-trending deep-crustal structures developed during uplift and volcanism in the Devonian. These have deformed the basement into a series of horsts and grabens. The deposit is hosted in folded Mesozoic and Cambrian sediments. The stratigraphy of the area consists of approximately 1000 m of dolomite and limestone with a paleo-weathering surface, overlain by 40 to 70 m of Mesozoic clastic sediments. This sedminetary sequence is believed to have been thrust over the Archean basement during the Mesozoic. Associated volcanism is present in the region.
The Kuranakh deposit is made up of 11 separate ore bodies, each consisting of a series of metasomatised, mineralisaed zones. Mineralisation occurs within the Yuhtinskaya Formation (a sequence of Jurassic sandstones) immediately above the unconformable contact with the Cambrian carbonate sequence. The contact is uneven with intermixing and brecciation of both sandstone and limestone with karstic sinkholes recognised in places. Mineralisation is restricted to lenticular bodies aligned N-NW with the most intense mineralisation concentrated in the central area at the intersection of a number of structures.
Ore bodies are stratabound, low in sulphides and are hosted along the contact between Cambrian Limestone and Jurassic sandstone. Mineralisation is spacially associated with and may be related to the same thermal event that produced igneous dykes, plugs and sills of lamprophyre, biotite-pyroxene porphyry, syenite-porphyry and trachyte. Extensive weathering has destroyed sulphides and resulted in large clay contents in the ore bodies ranging from 1% to 40%. Quartz is the main mineral present (40-85%) and iron hydroxides vary up to 13% in some deposits. Gold is found as free particles and is often associated with goethite signifying it was deposited with pyrite. Early workers documented minor marcasite, chalcopyrite, pyrrhotite, sphalerite, arsenopyrite and tellurides. At the base of the ore bodies intense metasomatism (clay-k-feldspar-quartz) is observed with vuggy quartz and open space-filling veinlets that extend beyond the metasomatite.
Kuranakh is one of the largest mines in Russia with historic production of 7.1 Moz (as of 2005). 2012 production was 138,000 oz.
JORC compliant mineral resourse estimate as at December 2012: measured and indicated resource of 85.3 Mt 4.7 Moz contained Au @ 1.71 g/t.
(Source: Armitage, M. et al., 2006. ZAO Polyus Resource and Reserve Audit: Kuranakh Gold Project. SRK Consulting. )
(Source: Rodionov, S.M. et al., 2005. The Kuranakh Gold Deposit, East Russia. Mineral Deposit Research: Meeting the Global Challenge (pp. 1053-1056). Springer Berlin Heidelberg .)