Shuangjianzishan Ag-polymetallic deposit, Bairin Left Banner (Balin Zuoqi), Chifeng City (Ulanhad League; Chifeng Prefecture), Inner Mongolia, Chinai

Regional Level Types
Shuangjianzishan Ag-polymetallic deposit	Deposit
Bairin Left Banner (Balin Zuoqi)	County
Chifeng City (Ulanhad League; Chifeng Prefecture)	Prefecture-level City
Inner Mongolia	Autonomous Region
China	Country

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Superlarge middle-low temperature magmatic-hydrothermal silver-polymetallic deposit, consisting of veins and stockworks hosted in Middle Permian siltstone and mudstone that are intruded by Yanshannian granites and diorite porphyry.

The Permian strata, including the Shoushangou, Dashizhai, Zhesi, and Linxi formations, are mainly composed of marine clastic rocks and intermediate–felsic volcanic rocks, with a small amount of continental calstic rocks. The ore bodies of the SJS deposit are mainly hosted in the Dashizhai Formation, which is predominantly characterized by marine thick sandstone layers, along with andesite, silty slate, altered andesite, basalt, and andesitic tuff, with a total thickness exceeding 900 m. The Mesozoic strata, including the Xinmin, Manketouebo, Manitu, and Baiyin’gaolao formations, are mainly composed of continental intermediate–felsic volcanic rocks and pyroclastic rocks with a small amount of calstic rocks. The Yanshanian granites are exposed 2 km northwest of the SJS deposit and lie concealed in the central part of the ore district. The concealed granite bodies revealed by deep drilling include biotite granite, syenogranite, and granite. In addition, granite porphyry, diorite porphyry, and rhyolite porphyry occur as NW- or NE-trending veins, dipping SW at ~60° and typically measuring up to 300 m long and 8 m wide, some of which are crosscut by Ag–Pb–Zn mineralized veins. The main structures in the ore district include the NE-trending Yaoerya–Pangjiawan anticline, NW-trending fracture zone, and NNE- and NW-trending faults.

The SJS Ag–Pb–Zn deposit was discovered in 2013 and was divided into two ore blocks, namely the western ore block (Shuangjianzishan ore block) and the eastern ore block (Xinglongshan ore block). The Xinglongshan ore block accounts for the vast majority of the total reserves of the SJS deposit. A total of 276 industrial orebodies have been delineated in the block, including 39 large-sized, 32 medium-sized, and 205 small-sized orebodies. However, only 4 industrial orebodies, including 1 medium-sized and 3 small-sized orebodies, have been delineated in the Shuangjianzishan ore block.

Three types of mineralization have been recognized at the Shuangjianzishan deposit: (1) porphyry-type Mo mineralization, (2) Cu-Sn-Ag-Zn-Pb quartz veins, and (3) epithermal Ag-Pb-Zn quartz-carbonate veins. The porphyry-type Mo mineralization is subeconomic. The vein-type Cu-Sn-Ag-Zn-Pb orebodies are between 0.5 and 13 m in width and hosted in the slates. A 1-m-wide core sample yielded grades of 10.40 wt % Cu, 1.34 wt % Sn, 525 g/t Ag, 0.52 wt % Zn, and 0.09 wt % Pb. The epithermal Ag-Pb-Zn quartz-carbonate veins are the most important mineralization type at the Shuangjianzishan deposit. The orebodies consist of veins hosted in the slate that are 0.5 to 28.6 m in width and 60 to 1,500 m in strike length and have a vertical extent from 50 to 600 m.

The Ag-Pb-Zn veins are the dominant mineralization type and are primarily hosted by slate. They consist of three substages: (1) quartz pyrite ± K-feldspar associated with K-feldspar alteration; (2) Ag-Pb-Zn mineralization associated with chlorite ± epidote ± illite ± quartz and quartz-illite ± calcite ± chlorite alteration; and (3) a late barren quartz substage.

The supergiant Shuangjianzishan (SJZ) Ag-Pb-Zn deposit is located in the southern Great Hinggan Range (SGHR), which reported proven reserves of 161.22×106 Mt ore volume, Ag metal content 15.5×103 Mt, Pb metal content 392×103 Mt, and Zn metal content 392×103 Mt.

The proven Ag reserves of the deposit are 21,665.17 t with an average grade of 128.53 g/t, and the proven Pb-Zn reserves are 1,915,278 t.

Commodity List

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Mineral List

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35 valid minerals. 1 (TL) - type locality of valid minerals.

Rock Types Recorded

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