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Nurkazgan, Samarka

Kazakhstan

Main commodities: Cu Au
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The Nurkazgan (or Samarka) porphyry Cu-Au deposit is located in northeastern Kazakhstan, 38 km NNW of Karaganda and 240 km southwest of Bozshakol (#Location: 50° 9' 40"N, 73° 0' 18"E).

The Nurkazgan deposit, previously known as Samarka, commenced operationas three small open pits in 2007, extracting ore at a grade of 0.65 to 1.1&% Cu, before going underground in 2009.

The deposit lies immediately to the west of a major north-south structure, marking a continental suture. It was emplaced during the Late Silurian to Early Devonian (410 Ma), in the 'Devonian' segment of the Kazakh-Mongol magmatic arc, and had been reported before 2004 as having a resource of >65 tonnes of Au and 1.5 Mt of Cu at grades of 1 to 3% (averaging 1.2%) Cu and 0.4 to 1 g/t Au (Seltmann et al., 2004 and references cited therein).

The measured + indicated resource at 1 January, 2011 quoted by IMC Consultants, 2011, comprises:
    200 Mt @ 0.89% Cu, 0.38 g/t Au, 2.02 g/t Ag, 0.1% Mo.
Production from 2007 to 2010 totalled 6.34 Mt @ 0.89% Cu (IMC Consultants, 2011).

The ore deposit is hosted by monzonite to quartz-diorite porphyries of the Turkulamsky Massif/Karaganda Intrusive Complex, intruding wall rocks of the Late Silurian to Devonian Zharsorskaya suite that comprise:
i). a lower unit of andesitic to basaltic agglomeratic tuffs, lavas and auto-magmatic breccias with rare interbeds of andesitic porphyry, tuffs, tuffaceous siltstones and tuffites;
ii). an upper sequence of andesitic to dacitic tuffites, tuffaceous conglomerate-breccias, tuffs and lavas with lenses of tuffaceous sandstones and conglomerates (Seltmann et al., 2004).

These rocks have been intruded by two or three phases of igneous intrusions from the Late Devonian to late Carboniferous. The orebodies are peripheral to the quartz-diorite in thecontact zone with the sedimentary and volcanic wallrocks. To th ewest of the intrusion, mineralisation occurs as generally, steeply west- and SW-dipping ore shoots and breccia pipes following the contact. On the eastern margin of the intrusion, the ore shoots are steeply east-dipping, accompanied by steep diorote-porphyry dykes sub-parallel to the regional fault direction. This major fault dips steeply to the west and cuts the eastern orebodies at depth and displaces the ore to become the SE Nurhazgan prospects (IMC Consultants, 2011)

The mineralised intrusives and country rocks are overlain by units of the terriginous, post-ore, Middle Devonian Konyrskaya suite, comprising red tuffaceous sandstones with lenses of boulder to pebble conglomerate, grits and siltstones.

Mineralisation took place as:
i). initial porphyry-style Cu, accompanying an early monzonite and
ii). an overprinting, high grade, high sulphidation Cu-Au phase related to the intrusion of a late stage porphyritic diorite and numerous associated breccia pipes.

The early porphyry-style mineralisation is predominantly composed of disseminations and stockworks of chalcopyrite, pyrite and molybdenite with grades of 0.3 to 0.5% Cu. It is accompanied by potassic alteration comprising K feldspar and biotite, and is surrounded by a propylitic halo characterised by chlorite and epidote. The overprinting high sulphidation phase, and its associated porphyritic diorite and breccia pipes, are localised in the core of the earlier monzonite intrusive and porphyry mineralisation. This phase is represented by a chalcocite-covellite-tetrahedrite assemblage with sericite-chlorite-carbonate alteration and has grades of >1 to 1.5%, locally to 3% Cu, and 1 g/t Au.

The high grade ore zone has an areal extent of at least 600 x 600 m and is restricted to depths of more than 200 to 300 m below the surface. At 700 m it has contracted to a steep 20 to 30 m wide band averaging 3% Cu. Mineable high grade ore has been delineated to a depth of 1400 m (Seltmann et al., 2004).

The most recent source geological information used to prepare this summary was dated: 2010.     Record last updated: 31/3/2013
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.


Nurkazgan

  References & Additional Information
 References to this deposit in the PGC Literature Collection:
Seltmann R and Porter T M,  2005 - The Porphyry Cu-Au/Mo Deposits of Central Eurasia: 1. Tectonic, Geologic & Metallogenic Setting and Significant Deposits: in Porter, T.M. (Ed), 2005 Super Porphyry Copper & Gold Deposits - A Global Perspective, PGC Publishing, Adelaide,   v.2 pp. 467-512
Seltmann, R., Porter, T.M. and Pirajno, F.,  2014 - Geodynamics and metallogeny of the central Eurasian porphyry and related epithermal mineral systems: A review: in    J. of Asian Earth Sciences,   v.79, pp. 810-841.

 References to this deposit in PGC Publications: Want any of our books ? Pricelist
Seltmann R and Porter T M, 2005 - The Porphyry Cu-Au/Mo Deposits of Central Eurasia: 1. Tectonic, Geologic & Metallogenic Setting and Significant Deposits,   in  Porter T M, (Ed),  Super Porphyry Copper and Gold Deposits: A Global Perspective,  v2  pp 467-512
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