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Koksai, Koksay
Main commodities: Cu Mo Au

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The Koksai (or Koksay) porphyry copper deposit is located in the Lake Balkhash region of Kazakhstan, 234 km NE of Almaty and 400 km to the southeast of the major Kounrad mine. It lies within the 'Balkhash-Ili' zone of the Upper Palaeozoic Kazakh-Mongol magmatic arc (#Location: 44° 28' 53"N, 78° 27' 26"E).

Koksai is associated intrusive porphyries cutting a sequence of Lower to Middle Carboniferous dacitic and rhyolitic lavas and tuffs, tuffaceous sandstones and sandstones of the Altynemelskaya suite (Visean-Moscovian) which unconformably overlies Silurian basement. The Silurian and Lower Carboniferous successions are unconformably overlain in turn by Middle Carboniferous gritstones and tuffaceous sandstones of the Batpakskaya suite (Middle Carboniferous) with sub-volcanic rhyolite and andesite porphyries, and extrusive equivalents.

The Silurian basement is cut by the Koksai laccolithic porphyry pluton which is unconformably overlain by both Carboniferous sequences and has radiometric ages of 520 to 425 Ma. Hydrothermally altered dykes of quartz-biotite plagiogranite porphyry cut both the Koksai pluton, and the two units of the Carbonifereous arc assemblage, while hydrothermal alteration (sericite+chlorite±sulphides) related to the porphyry copper deposit overprint both Silurian and Carboniferous country rocks. Consequently the mineralisation is assumed to be Late Carboniferous to Lower Permian in age (Abdulina and Chakabaeva, 1986).

The ore deposit is lens shaped, elongated in a WNW direction. Sulphides have been traced to a depth of 1000 m and comprise pyrite, chalcopyrite, magnetite, bornite and molybdenite. Alteration includes early silica-feldspar with associated chlorite, a subsequent acid quartz-sericite-chlorite stage and a late overprint characterised by calcite and sometimes barite (Seltmann et al., 2004).

The Koksai deposit comprises approximately 320 Mt @ 0.52% Cu, 0.049% Mo, 0.12 g/t Au, 0.049% Mo, 1.24 g/t Ag (Seltmann et al., 2004; Singer et al., 2008).

According to a Kazakhmys plc release dated 15 April 2014, the deposit comprises ~710 Mt @ 0.48% Cu, containing 3.4 Mt of copper.

Resource estimates published in KAZ Minerals Annual Report 2014 were:
    Measured resource of 282.062 Mt @ 0.46% Cu, 0.01% Mo,
    Indicated resource of 419.355 Mt @ 0.43% Cu,
    Measured+indicated resources - 701.417 Mt @ 0.44% Cu,
    Inferred resource - 436.779 Mt @ 0.36% Cu.

The most recent source geological information used to prepare this decription was dated: 2014.     Record last updated: 3/2/2016
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.


  References & Additional Information
   Selected References:
Shen, P., Pan, H., Hattori, K., Cooke, D.R. and Seitmuratova, E.,  2018 - Large Paleozoic and Mesozoic porphyry deposits in the Central Asian Orogenic Belt: Geodynamic settings, magmatic sources, and genetic models: in    Gondwana Research   v.58, pp. 161-194.

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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