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Daugystau, Daugyztau |
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Uzbekistan |
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Au
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Super Porphyry Cu and Au
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The Daugystau (Daugyztau) gold deposit is located approximately 30 km south east of the city of Zarafshan and 10 km southwest of the Amanataytau gold deposit in the central Kyzylkum region of western Uzbekistan (#Location: 41° 13' 57"N, 64° 12' 23"E).
Daugystau is hosted within a pile of imbricated thrusts that was deformed into east-westÐtrending synforms and antiforms exposed towards the western limit of the southern Tien Shan tectonic province. It is hosted by a sequence of sandstones, siltstones and shales of the Mid-Cambrian and Mid-Ordovician to Lower Silurian Besapan Formation, the same host as at Muruntau and Amantaytau (see separate records).
The Daugystau and nearby Amantaytau deposits represent parts of a single system which have been dextrally offset by 10 km. It is also several tens of kilometres to the south-west of Muruntau along the trend of the Muruntau-Daugystau Fault Zone.
Mineralisation at Daugystau is present in vein systems which show evidence of both brittle and ductile deformation. The veins are commonly mylonitised, show ribbon structure, and contain highly sulphidic breccia fragments. All veins are localised within the ENE striking regional shear zone near its intersection with a NNW trending zone of shearing that is parallel to the fold axes in the region. The ores occur predominantly in large veins along steeply dipping NNE and north-east trending fractures. In the northern Daugystau field where the NNW and ENE shear zones intersect, stockwork-like ores are also present (Berger, etal., 1994). Mineralisation is believed to have been emplaced between 260 and 270 Ma (Yakubchuk et al., 2002).
Gold occurs predominantly with pyrite, arsenopyrite, minor stibnite and silver sulpho-salts, and ankeritic carbonate. Wall rock alteration consists of early albitisation, then quartz, chlorite, muscovite and ankeritic carbonate, followed by the final stage of carbonate alteration.
Gold is present in Ag rich ores in association with Pb and Sb sulpho-salts. The Vysokovltnoye deposit at the southern end of the Daugystau ore field contains bonanza grade Ag-Pb-Sb-Au ores in veins (Berger, etal., 1994).
According to Dunin-Barkovskaya et al. (2005), there are three main mineral associations: i). chlorite-quartz; ii). gold-arsenopyrite-pyrite (the main ore); and iii). sphalerite-fahlore-antimony. Fahlore is the tetrahedrite-tennantite solid solution. Pyrite, arsenopyrite and stibnite are the principal sulphides, with less widespread marcasite, sphalerite, tetrahedrite, chalcopyrite and gold. In the primary ores, gold is associated with pyrite and arsenopyrite in the early assemblages (comprising up to 90% of all gold in the deposit). The average Au content in pyrite disseminations is 37 g/t Au; 90 g/t in pyrite from veinlets; and 251 g/t in arsenopyrite. Microprobe analysis shows that gold mainly occurs in an invisible form, and has been measured at local elevated concentrations of up to 910 g/t in pyrite and 890 g/t in arsenopyrite. Larger gold grains, up to 50 µm in diameter, are associated with the sphalerite-tetrahedrite-tennantite association, although these are rare. The temperature of deposit formation has been shown to be within the range 180 to 300°C.
The known resource at Daugystau totals 550 t of Au based on Soviet era testing patterns and reserve classifications, comprising 200 t of Au in the C1 class and 350 t in C2, all at an average grade of 4 g/t Au. Mineralisation is known to a depth of 650 m. The resource is divided into an open pit project on which work started in 1986, and a prospect which was still being evaluated in the mid 1990's.
The most recent source geological information used to prepare this decription was dated: 2004.
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.
Daugyztau
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Selected References:
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Dunin-Barkovskaya, E.A., Aripov, U.K., Tsoy, L.A. and Kim, M.A., 2005 - Mineralogical features and ore-forming conditions of goldbearing deposits of Uzbekistan: in IGCP Project 486, 2005 Field Workshop, Kiten, Bulgaria, 14-19 September 2005 Geochemistry, Mineralogy and Petrology, Bulgarian Academy of Sciences, v.43, pp. 69-74.
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Zverev, Yu., Kremenetsky, A., Minzer, E. and Shatov, V. 1999 - The Amantaitau-Daughyztau ore field: in Shayakubov, T., Islamov, F., Krementsky, A. and Seltmann, R., (Eds.), Au, Ag, and Cu deposits of Uzbekistan International Field Conference of IGCP-373, Excursion B6 of the Joint SGA-IAGOD symposium, London/Tashkent, 27/28 August - 4 September 1999 Excursion guidebook pp 17-36
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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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