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Zhuxi |
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Jiangxi, China |
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W Cu
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Super Porphyry Cu and Au
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The Zhuxi tungsten-copper deposit is located in Jiangxi Province, central eastern China, 15 km SE of Jingdezhen and 320 km SE to ESE of Wuhan.
It lies within the northeastern section of the South China Block, that was formed by the Neoproterozoic collision between the Yangtze and Cathaysia blocks during the final stages of the amalgamation of the Rodinia supercontinent (e.g., Charvet, 2013; Yao et al., 2013) (Shu et al., 2006; Mao et al., 2011; Shu, 2012). The northern margin of South China Block is defined by the Qinling-Dabie Orogenic Belt which marks the Triassic continental collision between the South and North China blocks. On its eastern margin, that orogenic belt is offset hundreds of kilometres by the major sinistral Tan-Lu Fault to become the Sulu Orogenic Belt in eastern China and on the Jiaodong Peninsula. Zhuxi is situated ~100 km ESE of the Tan-Lu Fault along the eastern projection of the Qinling-Dabie Orogenic Belt.
It is also situated within and near the northwestern edge of the 1500 km long NE to ENE trending Neoproterozoic Jiangnan Orogen that separates the Yangtze and Cathaysia blocks to the NW and SE respectively, and resulted from the collision of these two terranes. The Jiangshan-Shaoxing fault, which defines the southern boundary of the Jiangnan Orogen, and is interpreted as the Yangtze-Cathaysia block boundary (Wang et al., 2013), is ~100 km SE of Zhuxi.
The Jiangnan orogenic belt includes Neoproterozoic greenschist facies arc terranes with 860 to 825 Ma detrital zircon ages cut by the undeformed ~819 Ma Neoproterozoic Jiuling granites (Li et al., 2003; Zheng et al., 2007; Sun et al., 2017). Following the Jiangnan Orogeny, these rocks were eroded and unconformably covered by the Nanhua rift sequence, which was emplaced in a series of Cryogenian ~820 to ~750 Ma rift basins (Wang and Li, 2003; Wang et al., 2014), and overlain by terrigenous sedimentation from the Ediacaran (Sinian) to the Middle Ordovician (Charvet et al., 2010) and by Carboniferous to Permian carbonate and sporadic Triassic clastic rocks. During the Jurassic to Cretaceous, an extensive and voluminous granitic province formed in the South China block with associated W-Sn deposits. Most of these granites and the associated deposits are located in the Nanling Range (Mao et al., 2007) and form a cluster of W-rich deposits and prospects, including the Dahutang W-Cu-Mo, Xianglushan W, Yangchuling W-Mo, Zhuxi W-Cu, Baizhangyan W-Mo, Jitoushan W-Mo, Gaojiabang W-Mo and Dongyuan W-Mo, have been located on the northeastern extremity of the Jiangnan Orogen. Zhuxi is the largest tungsten of these (Sun, et al., 2019; Yuan, et al., 2019).
The Zhuxi deposit is located in the centre of the NE-trending Taqian-Fuchun basin which was filled with Carboniferous to Permian carbonate and sporadic Triassic clastic rocks that unconformably overlie the Neoproterozoic metasedimentary rocks of the Shuangqiaoshan Group (He et al., 2011; Chen, 2014; Liu et al., 2014). The Shuangqiaoshan Group comprises a thick suite of greenschist facies turbiditic metasedimentary rocks, including tuffaceous sandstone, phyllite, phyllitic slate, tuff with lesser basalt and metamorphic felsic extrusive rocks (Liu, 1997). The Middle Carboniferous Huanglong Formation and Upper Carboniferous Chuanshan Formation are composed of limestone and minor dolomite, unconformably overlying the Shuangqiaoshan Group (Chen et al., 2012). The Permian Xixia Formation comprises a suite of limestone and siliceous limestone sandwiched by quartz sandstone (Pan et al., 2017). The Triassic Anyuan Formation contains argillaceous carbonate, fine conglomerate and some quartz sandstone (Sun, et al., 2019; Yuan, et al., 2019).
The fault dissected and eroded remnants of the Taqian-Fuchun basin are ~60 km long and 2 to 6 km wide, bounded by NE-trending faults. The dominant structures in the immediate Zhuxi deposit area are NE-trending with secondary east-west trending faults. These include a major NE-trending regional-scale fault (Fault 1) that is several hundred kilometres long and controls the basin architecture and distribution of carbonate rocks. A second parallel ∼4 km long, 30 to 70°SE dipping fault (Fault 2) controls the location of most of the granitoids and ore bodies in the deposit. Several smaller 100 to 500 m long east-west and north-south trending faults can be observed in the deposit area. The intersection of the NE and east-west trending faults commonly control the emplacement of granitoids and the distribution of the ore bodies (Sun, et al., 2019; Yuan, et al., 2019).
Several ~149 to 146 Ma granitic intrusions, comprising diorite porphyry, lamprophyre, two-mica porphyritic granite, granite porphyry, muscovite granite, biotite granite, granodiorite and monzonite intrude the Neoproterozoic basement and Carboniferous Huanglong and Chuanshan formations and the Permian Xixia Formation (Su, 2014; Wang et al., 2014; Hu, 2015; Chen et al., 2015). The diorite porphyry and lamprophyre are well exposed on the surface, whilst the other intrusive rocks are only encountered in the subsurface (Sun, et al., 2019).
Skarn alteration and mineralisation in the Zhuxi W-Cu deposit are closely related to three granites, a two-mica porphyritic granite, muscovite granite and granite porphyry (Chen et al., 2012). These granites occur as at least one larger central, and an associated swarm of smaller, mostly sill like bodies that are distributed over a zone that is >1 km long in the immediate deposit area, but appears to continue down dip. These intrusion range in thickness from <10 to >200 m. The larger sill-like granite, which is up to 200 m thick, is located in the core of the >1 km wide skarn alteration halo.
The skarn alteration is zoned outward from the central granite intrusion into wall rock persisting over a width of >0.5 km into a surrounding marble zone on either side of the intrusion. Sections of the central granite has been altered to greisen. The outward skarn zonation is from clinopyroxene-garnet → garnet-clinopyroxene → tremolite-actinolite → garnet-bearing marble, respectively. Scheelite mineralisation is closely related to the garnet-clinopyroxene and tremolite-actinolite zones.
The orebodies within the skarn altered zone are composed of calc-silicate, scheelite and sulphides, mainly occurring as lenses above the Fault 2 faulted contact between the Neoproterozoic metasedimentary basement rocks and the overlying Carboniferous carbonate strata, mostly below and partly within the main central intrusion. The ore bodies are predominantly hosted by the Carboniferous Huanglong Formations, with lesser mineralisation in the Carboniferous Chuanshan and Permian Xixia formations (Sun, et al., 2019; Yuan, et al., 2019). The latter two appear to largely host a narrow rind around the intrusive contact of the larger core granite 'sill'.
More than 100 individual copper and tungsten ore veins and lenses make up the Zhuxi W-Cu deposit (Pan et al., 2017). Most vary from several to several tens of metres in thickness, and roughly parallel the host carbonate bedding, with NE strikes and 70 to 85° dips above the 500 m level, and 40 to 50° dips below that.
The tungsten orebodies mostly follow the skarn, with minor mineralisation within the greisen and in the phyllite of the Shuangqiaoshan Group. The Cu mineralisation is also mainly developed within the skarn, and locally extends into the granite. The principal ore minerals are scheelite and chalcopyrite, with accompanying pyrrhotite, sphalerite and galena, and the gangue minerals include garnet, diopside, actinolite, epidote, calcite and fluorite (Yuan, et al., 2019).
The deposit has reserves of (Sun, et al., 2019; Yuan, et al., 2019):
3.44 Mt of contained WO3 in ~640 Mt of ore @ 0.54% WO3;
0.01 Mt of contained Cu in ~1.75 Mt of ore @ 0.57% Cu.
The most recent source geological information used to prepare this decription was dated: 2019.
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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Hong, J., Zhang, H., Li, D., Ouyang, Y., Zhai, D., Li, F. and Liu, J., 2022 - In situ LA-ICP-MS U-Pb geochronology and geochemical characteristics of garnet from the Zhuxi skarn W-Cu deposit, South China: in Ore Geology Reviews v.140, 18p. doi.org/10.1016/j.oregeorev.2021.104577.
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Song, S., Mao, J., Xie, G., Chen, L., Santosh, M., Chen, G., Rao, J. and Ouyang, Y., 2019 - In situ LA-ICP-MS U-Pb geochronology and trace element analysis of hydrothermal titanite from the giant Zhuxi W (Cu) skarn deposit, South China: in Mineralium Deposita v.54, pp. 569-590.
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Sun, K., Chen, B. and Deng, J., 2019 - Ore genesis of the Zhuxi supergiant W-Cu skarn polymetallic deposit, South China: Evidence from scheelite geochemistry: in Ore Geology Reviews v.107, pp. 14-29.
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Yuan, L., Chi, G., Wang, M., Li, Z., Xu, D., Deng, T., Geng, J., Hu, M. and Zhang, L., 2019 - Characteristics of REEs and trace elements in scheelite from the Zhuxi W deposit, South China: Implications for the ore-forming conditions and processes: in Ore Geology Reviews v.109, pp. 585-597.
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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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