The Amantaytau (Amantaitau) gold deposit is located 30 km south east of the city of Zarafshan in the central Kyzylkum region of western Uzbekistan .
The deposit occurs within a pile of imbricated thrusts that was deformed into east-westtrending synforms and antiforms exposed towards the western limit of the southern Tien Shan tectonic province. It is hosted by a sequence of carbonaceous flyschoid rocks of the Cambrian to Silurian Besapan Formation, which have been complexly deformed and metamorphosed in the compressional thrust-fold belt. The deposit lies within a linear zone, known as the Amantay-Daugyz-Vysokolt'noye Zone, which is tens of kilometres long and is internally zoned. The Amantaytau orebodies, which comprise gold and sulphide ores accompanied by sericite alteration, lie at one end of this zone, while silver-sulphosalt mineralisation in quartz-chlorite-albite metasomatites is found at the other (Zakharevich, 1993). The Amantaytau and nearby Daugystau (see separate record) deposits represent parts of a single system which have been dextrally offset by 10 km.
The orebodies at Amantaytau constitute a system of stockworks within north-west trending faults, which are truncated by 'through-going' north-east trending faults. The individual stockworks form relatively narrow zones which are steeply dipping, generally at >60°. Ore has been outlined to a depth of 600 m. The host rocks were originally slightly carbonatic and slightly ferruginous, arkosic, polymict, greywacke and tuffaceous sandstone; polymict greywacke siltstones; and, silty and pelitic mudstone. The ore lies in the area of greatest alteration where the rocks have lost their bedded structure, are hydrothermally altered, and have cataclastic textures. The gold and silver mineralisation is predominantly localised within the meta-pelites, which have been very slightly de-silicified in parallel with an enrichment in Al. K was introduced, while Na was removed for a net decrease in the alkalis. Alteration appears to largely take the form of sericitisation (Zakharevich, 1993). Mineralisation is believed to have been emplaced between 260 and 270 Ma (Yakubchuk et al., 2002).
The known resource at Amantaytau is of the order of 700 t of Au at a grade of 7.5 g/t Au in the oxide ore and 14.2 g/t Au in the primary sulphides. These resources/reserve are based on Soviet era testing patterns and reserve classifications, and include 250 t of Au in class C1 and 450 t in class C2. The deposit was discovered in 1975, with detailed exploration beginning in 1980. The results of subsequent JORC compliant testing and reclassification of the reserves and resources by Oxus Gold plc are:
Sulphide Ore - Amenable to underground mining via decline access, using trackless mining equipment.
Reserve - 60 tonnes of Au @ 12g/t Au; Total resource - 84 t of Au at 12 g/t Au.
Oxide Ore - Amenable to open pit mining.
Proven + probable reserve of 5.47 Mt of ore @ 11.54 g/t Au (63 t Au); Total resource of 7.15 Mt of ore @ 11.68 g/t Au (83 t Au).
with significant potential to expand the reserves and resources based on more widely spaced drill intersections.
(Source: Porter GeoConsultancy, www.portergeo.com.au, 2002)