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Shizhuyuan |
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Hunan, China |
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W Sn Bi Mo F
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Super Porphyry Cu and Au
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The Shizhuyuan skarn scheelite/wolframite (W-Sn-Bi-Mo-F) deposit is located some 15 km south-east of Chenzhou City in southern Hunan Province, China. It is one of the largest known economic grade tungsten deposit in the world.
Geological Setting
The Shizhuyuan tungsten deposit lies within the Nanling tin-tungsten metallogenic province and is one of a cluster of deposits that straddle the boundary between the Yangtze Craton to the NW from the Cathaysia Block to the SE. These two tectonic entities had been sutured along the NE-SW Qinhang Tectonic Belt between 1.1 and 0.83 Ga to become the South China Block. The boundary between the two is marked by the regional Chenzhou-Linwu Fault. Studies have shown that in the western part of this metallogenic province, the W and Sn mineralisation took place at different times. W mineralisation is interpreted to have been related to Triassic granites, whereas the Sn is associated with Late Jurassic granites. Tungsten-tin deposits such as Shizhuyuan, which an ore associated molybdenite Re-Os age of 151.0 ±3.5 Ma, is interpreted to be associated with Late Jurassic granite dated at 154.9 ±0.8 (Zhao et al., 2022). The most significant other deposits in the Nanling tin-tungsten metallogenic province include the Furong skarn, greisen and vein deposit, 45 km to the SW, which contains 0.70 Mt of contained Sn at a grade of 0.3 to 1.5% Sn, with a cassiterite U-Pb age of 158.2 ±0.4 Ma, associated with a 157.5 ±0.3 Ma granite (Yuan et al., 2011). The Triassic tungsten mineralisation is exemplified by the Shuiyuanshan greisen deposit which is 12 km NW of Shizhuyuan and contains 0.11 Mt of contained WO3 at a grade of >0.11 WO3, and an ore associated molybdenite Re-Os age of 219.5 ±3.4 Ma, related to a 224 to 217 Ma granite, (Zhao et al., 2022).
NOTE: Much of the summary below is based on Lu et al., 2003, and as such some age ranges may vary from those listed above from the more recent Zhao et al. (2022).
Shizhuyuan is hosted by a sequence of middle to upper Devonian sediments, predominantly carbonates, unconformably overlying Sinian (late Proterozoic to early Cambrian) sandstone and slate. These are intruded by the multi-phase Yenshanian (mid Jurassic to Cretaceous) Qianlishan Granite complex occupying an area of 9.5 km2.
The stratigraphic succession in the Shizhuyuan area can be summarised as follows:
Quaternary - Alluvium
Upper Devonian
• Unit D4 - Chert and muddy limestone.
• Unit D3 - Thin and medium thick bedded muddy, veined limestone.
Middle Devonian
• Unit D2 - Grey to white, shallow water, micaceous limestone.
• Unit D1 - Grey to white quartz sandstone.
Unconformity
Sinian - Late Proterozoic to Lower Cambrian
• Unit Z - Micaceous sandstone and slate.
The Yenshan Qianlishan Granite complex was intruded as five separate pulses, comprising early (187 to 182 Ma) fine grained porphyritic phases, medium grained biotite-K feldspar granite (163 to 158 Ma), fine grained biotite and K feldspar granite, granitic porphyry (146 to 144 Ma) and 142 Ma dolerite. The upper part of the complex is extensively greisenised.
The orebody occurs on the eastern flank of a synclinal structure, the core of which is intruded by the granitic complex. To the east and west, mid Devonian sandstones are exposed in the core of adjacent anticlines.
Prominent NE-SW faults are developed in the area with lesser N-S and NW-SE structures.
Mineralisation
Mineralisation occurs within three flat lying, generally, cross cutting, skarn layers immediately above, and generally parallel to the overall horizontal upper surface of the Yenshan granite. These mineralised layers are developed in the core of a local syncline with bedding dips of up to 40°.
Mineralisation is developed over an area of 800 to 1000 m x 600 to 800 m and is from 100 to 300 m thick. It comprises: i). Sn-Be veinlet ore in marble and porphyry, ii). massive W-Bi-Mo-Sn skarn ore, iii). stockwork W-Sn-Bi-Mo-F ore superimposed on massive skarn and greisen ores and iv). W-Sn-Mo-Bi greisen ore mainly associated with the medium grained biotite-K feldspar granite, the emplacement of which was accompanied by intense fracturing that controlled the development of veining and stockworks. The stockwork ore mainly comprises greisen and skarn veinlets with scheelite, wolframite, molybdenite, cassiterite, bismuthinite and fluorite. This ore has been dated at 157 Ma.
The three mineralised zones from top to bottom comprise:
Zone 1 - The marble/cassiterite zone, up to 150 m thick, comprising 75 Mt of 0.16% Sn. This is regarded as sub economic mineralisation.
Zone 2 - The W/Bi skarn zone, comprising scheelite and bismuthinite in a skarn composed of garnet, diopside, vesuvianite, hornblende and fluorite. This zone is 75 to 200 m thick, and totals 105 Mt of 0.23% WO3, 0.1% Bi and 0.12% Sn.
Zone 3 - The W/Mo/Bi greisen skarn zone containing scheelite, wolframite, molybdenite and bismuthinite in skarns comprising garnet, diopside, hornblende, feldspar, quartz and fluorite. This zone is up to 150 m thick, comprising around 85 Mt of 0.48% WO3. Within this there is a high grade core of 35 Mt @ 0.62% WO3, 0.14% Mo, 0.16% Bi and 0.08% Sn. This high grade core is 300 x 300 m in plan and 50 to 150 m thick.
These reserve figures are based on a cut-off grade of 0.15% WO3. Pb/Zn/Sn lenses occur on the margins of the main tungsten deposit.
Zone 3 occurs immediately above the granite. The upper surface of the granite is undulose and cross-cuts Zone 3 in places to come into contact with Zone 2. The dominant mineralogy comprises zones of garnet, garnet-pyroxene, vesuvianite-garnet and wollastonite-vesuvianite progressively outwards from the intrusives. These have been subjected to later retrogression.
Zhao et al. (2022) quote reserves of contained metal at Shizhuyuan as 0.80 Mt WO3 and 0.49 Mt Sn.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2003.
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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Selected References:
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Lu, H.-Z., Liu, Y., Wang, C., Xu, Y. and Li, H., 2003 - Mineralization and fluid inclusion study of the Shizhuyuan W-Sn-Bi-Mo-F skarn deposit, Hunan Province, China: in Econ. Geol. v.98, pp 955-974.
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Mao, J., Cheng, Y., Chen, M. and Pirajno, F., 2013 - Major types and time-space distribution of Mesozoic ore deposits in South China and their geodynamic settings: in Mineralium Deposita v.48, pp. 267-294.
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Wu, S., Mao, J., Ireland, T.R., Zhao, Z., Yao, F., Yang, Y. and Sun, W., 2019 - Comparative geochemical study of scheelite from the Shizhuyuan and Xianglushan tungsten skarn deposits, South China: Implications for scheelite mineralization: in Ore Geology Reviews v.109, pp. 448-464.
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Wu, S., Mao, J., Yuan, S., Dai, P. and Wang, X., 2018 - Mineralogy, fluid inclusion petrography, and stable isotope geochemistry of Pb-Zn-Ag veins at the Shizhuyuan deposit, Hunan Province, southeastern China: in Mineralium Deposita v.53, pp. 89-103.
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Yin, J., Kim, S.J., Lee, H.K. and Itaya, T., 2002 - K-Ar ages of plutonism and mineralization at the Shizhuyuan W-Sn-Bi-Mo deposit, Hunan Province, China: in J. of Asian Earth Sciences v20 pp 151-155
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Zhao, P., Yuan, S., Williams-Jones, A.E., Romer, R.L., Yan, C., Song, S. and Mao, J., 2022 - Temporal Separation of W and Sn Mineralization by Temperature-Controlled Incongruent Melting of a Single Protolith: Evidence from the Wangxianling Area, Nanling Region, South China: in Econ. Geol. v.117, pp. 667-682.
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Zhong, J., Chen, Y.-J. and Pirajno, F., 2017 - Geology, geochemistry and tectonic settings of the molybdenum deposits in South China: A review: in Ore Geology Reviews v.81, pp. 829-855
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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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