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Ingichkin

Uzbekistan

Main commodities: W
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The Ingichkin skarns scheelite deposit formed from marbles within a Silurian sequence, adjacent to a middle to late Carboniferous granitoid stock and lies within the same belt that contains the major South Tien Shan gold deposits of Uzbekistan.

The intruded country rock in the Ingichkin area is composed of Palaeozoic shales, siltstone, limestone, sandstones, grits, conglomerates, marls and clays. These have been intruded by middle to late Carboniferous granites and granodiorites, with small stock like bodies of andesite-dacite porphyry, granosyenite, granodiorite, leucocratic and aplitic granites and olivine micro-dolerites. In addition there is a middle Carboniferous dyke complex of lamprophyres, granodiorite porphyry and quartz-porphyry. The intrusive complex has three phases, an early granite and granosyenite; a middle granite to granodiorite; and a late leucocratic and aplitic granite stage. Mesozoic sediments overlie these Palaeozoic rocks (Smirnov, 1977).

The Ingichkin deposit is associated with the contact between the middle phase granitoids and late Silurian sediments and volcanics. The roof of the batholith is very undulose, influenced by pre-intrusion folding of the Palaeozoic volcano-sedimentary sequence. The best skarn is developed in areas of greater fracturing, and in indentations within the granitoid contact. Skarn occurs: i). along the contact of the granitoids with marble beds; ii). as discordant zones fringing dykes and joints within the marbles; and iii). as replacements following bedding outwards from the contact. The first style accounts for 90% of the ore, with near 10% in the discordant group and 1% in the stratabound classification (Smirnov, 1977).

The following five skarn types are present: i). pyroxene, including hedenbergite, salite and diopside; ii). garnet-pyroxene; iii). garnet-idocrase-pyroxene; iv). garnet; and v).  wollastonite.

The pyroxene skarn is the most common. Twenty two contact skarn bodies are recognised, occurring over a vertical interval of 800 m. The thickness of the contact skarns varies from a few cms to 26.5 m, averaging 0.4 m over two thirds of the total area, and more than 1 m in the remainder. The discordant skarns average 0.6 to 0.8 m in thickness. Tungsten mineralisation is present predominantly as scheelite, but is very irregularly distributed. Scheelite, quartz and sulphides increase outwards from the contact within the skarn, while the amount of garnet, pyroxene and calcite decreases. Molybdenum is absent from the scheelite, although yttrium and rare earths are present (Smirnov, 1977).

Production in the early 1990s amounted to around 0.5 Mt @ 0.285% WO3 per annum.

The most recent source geological information used to prepare this summary was dated: 1997.    
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

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 takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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