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Kuoerzhenkuola (Kurzhenkula), Buerkesidai |
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Xinjiang, China |
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Au
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Kuoerzhenkuola or Kurzhenkula and Buerkesidai epithermal gold deposits are located in the Sawur Gold Belt of the eastern Sawuer Mountains, ~400 km NNW of Urumqi in northern Xinjiang, China, within 10 km east of the border with Kazakhstan.
The Sawur Gold Belt, occurs along or parallel to the WNW-ESE trending Irtysh Fault, marking the boundary between the Altai Orogen (Central Asian Orogenic Belt) and the Junggar microplate to the immediate south. Other deposits and occurrences within this gold belt are distributed over an ~100 km WNW-ESE interval and include: Kekekuola; Hanzheganeng; Heishantou; Hatu; Lukeyi; and Huilushan.
The deposit is hosted in an Early Carboniferous pre-collisional volcanic arc setting, towards the eastern end of the Zharma-Sawur Palaeozoic arc, which is interpreted to be related to oceanic plate subduction along the Jeson-Armantai ophiolite belt (Shen et al.,2007, 2008). Regional lithostratigraphy includes Early Carboniferous andesite, andesite porphyry, sandstone, siltstone, mudstone and limestone of the Sawur and Heishantou Formations. Late Palaeozoic granodiorites, granites, diorite porphyries, albite-porphyry dykes and breccia pipes are widely developed in the region. Main principal structures are ENE trending folds and major east-west-trending and minor NE- and NW-trending faults.
The Kuoerzhenkuola orefield incorporates two epithermal systems distributed along two east-west trending faults, Kuoerzhenkuola to the south and Buerkesidai in the north. Early Carboniferous felsic and andesitic rocks and breccia pipes occur in the centre of the orefield. The breccia pipes mainly comprise andesitic porphyry and basaltic andesitic lava. WNW trending faults control the location of six Au-bearing alteration zones that are individually hundreds to thousands of metres in length and 10 to 30 m in width. The hydrothermal alteration assemblage include kaolin, silica, sericite, chlorite, epidote, alunite and fluorite. On the basis of the presence of strong kaolinite and alunite alteration the deposit is interpreted to be a high sulphidation-style epithermal system (Shen et al., 2007, 2008; Zeng et al., 2007).
All the gold orebodies are hosted within these alteration zones. The largest is 1700 m long by 1.6 to 10 m wide, with albite-porphyry dykes commonly occurring in both hanging and footwalls. Ore grades vary from 2.6 to 79 g/t, average 7.3 g/t Au. The deposit is estimated to contain ~11.7 t of gold at an average grade of 6.02 g/t Au which equates to ~1.94 Mt of ore (Shen et al., 2008)
Two types of ore are recognised: i). sulphide-quartz stockworks, disseminations and breccias; and ii). massive sulphide-quartz veins (Shen et al., 2008). Ore minerals are predominantly pyrite, chalcopyrite, pyrrhotite and native gold, in a gangue suite that includes quartz, montmorillonite, kaolinite, chlorite, epidote, calcite and alunite. Two generations of gold deposition have been described.
• Stage I, which only results low-grade ores and comprises a pyrite-quartz assemblage, with minor pyrrhotite, chalcopyrite and quartz filling fractures. The sulphides of this generation and host rocks are brecciated and cemented by quartz and sulphides as a result of the later successive hydrothermal stages.
• Stage II is the main and high-grade ore-forming event, producing fine grained polymetallic sulphide-quartz stockworks, disseminated fine-grained polymetallic sulphide-quartz ores and brecciated quartz-sulphides. The ore fluids are estimated to have varied between 119 and 276°C, with salinities between 2.7 and 7.9 wt.% NaCl equiv., with the fluids having an Na+-HS--Cl--H2O composition (Shen et al., 2007, 2008). The same authors inferred gold was transported as an Au-S complex and was precipitated under reducing condition.
Stable isotopic data after Zeng et al. (2007) are interpreted to indicate fluid-mixing and water-rock interactions resulted in gold precipitation. The volcanic-subvolcanic rocks have been dated at 343±22 Ma (Liu et al., 2003), suggesting the maximum age mineralisation is 343 Ma, supported by a Rb-Sr isochron age of 341±30 Ma obtained from gold-bearing quartz vein (Cai et al., 2000) and two 40Ar/39Ar ages of 332±22 Ma from fluid inclusions also from auriferous quartz vein (Shen et al., 2007, 2008).
The most recent source geological information used to prepare this decription was dated: 2011.
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.
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Pirajno, F., Seltmann, R. and Yang, Y., 2011 - A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China: in Geoscience Frontiers v.2, pp. 157-185.
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Shen, P., Shen, Y., Liu, T., Li, G. and Zeng, Q., 2007 - Genesis of volcanic-hosted gold deposits in the Sawur gold belt, northern Xinjiang, China: Evidence from REE, stable isotopes, and noble gas isotopes: in Ore Geology Reviews v.32, pp. 207-226.
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Yang, F., Mao, J., Bierlein, F.P., Pirajno, F., Zhao, C., Ye, H. and Liu, F., 2009 - A review of the geological characteristics and geodynamic mechanisms of Late Paleozoic epithermal gold deposits in North Xinjiang, China: in Ore Geology Reviews v.35, pp. 217-234.
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Yuan, F., Deng, Y.-F., Zhou, T., Zhang, D., Xu, C., Jowitt, S.M., Zhang, R. and Zhao, B., 2017 - Petrogenesis and timing of emplacement of porphyritic monzonite, dolerite, and basalt associated with the Kuoerzhenkuola Au deposit, Western Junggar, NW China: implications for early Carboniferous tectonic setting and Cu-Au mineralization prospectivi: in International Geology Review v.59, pp. 1154-1174.
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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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