Dajing Sn-Cu-polymetallic deposit, Linxi County, Chifeng City (Ulanhad League; Chifeng Prefecture), Inner Mongolia, Chinai

Regional Level Types
Dajing Sn-Cu-polymetallic deposit	Mine
Linxi County	County
Chifeng City (Ulanhad League; Chifeng Prefecture)	Prefecture-level City
Inner Mongolia	Autonomous Region
China	Country

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Large-scale copper-tin-polymetallic ore deposit with Sn, Cu, Pb, Zn, Ag and minor elements such as Co and In, hosted by rocks of the Upper Permian Linxi group (terrigenous lacustrine sedimentary rocks, consisting of sandstone, slate, pelitic-silty slate, medium-to fine-grained graywacke, siderite nodule- and P-siderite nodule-bearing siltstone, and marl), in the southwest part of the Huanggang-Wulanhaote metallogenic belt. Orebodies are mainly developed in the upper part of the marl layer and below the P-bearing horizon. Multiperiodic activities of the host structures system led to a multistage mineralization. Four stages are recognized in the main mineralization: 1) cassiterite-arsenopyrite-quartz stage, 2) cassiterite-sulfide (or Cu-polymetallic mineralization) stage, 3) massive pyrite stage, and 4) galena-sphalerite stage. Wallrock alterations are silicification, sericitization, sideritization, chloritization, tourmalinization, dolomitization, calcitization and fluoritization.

Large polymetallic deposit containing 1.5 Mt Zn, 0.30 Mt Pb, 0.30 Mt Cu, 75 kt Sn, and 3.3 kt Ag, as well 768 t In in an average grade of 112 ppm. Ore veins in this deposit are mainly hosted by Permian sandstone.
The Dajing deposit has yielded over 690 ore bodies, besides numerous stockworks and disseminations since its discovery in the 1970 s. The cumulative resources were estimated to consist of 84 kt of Sn, 330 kt of Cu, 1.98 Mt of Pb and Zn, and 4 kt of Ag, making the Dajing deposit one of the largest tin deposits in northern China. Notably, the Sn and Ag resources reach large sizes, while Cu resources correspond to a medium size. The polymetallic tin and sulfide ore bodies at Dajing are predominantly subterranean, influenced mainly by NW-trending faults and modified by post-mineralization tectonic events, resulting in Z-shaped. The No.7 orebody with an average grade of 1.58 % Cu, 0.33 % Pb and 0.6 % Zn, one of the most typical Cu polymetallic orebodies, mainly occurs in the marl segment of the Linxi Formation. The No.66 orebody, controlled by a fracture zone, is the most important Sn-Cu orebody with average grades of 0.76 % Cu and 0.45 % Sn. The extended depth, length, thickness, strike, and dip angle of the orebody are 190 m, 180 m, 0.22 –3.56 m, 100°-130°, and 46°-67°, respectively. High-grade zones of Sn (>1.12 %) and Cu (>4.7 %) are mainly located in the central part of the mining area. In contrast, high-grade Zn (>4%) and Pb (>3.75 %) demonstrate a strong regional association, mainly occurring at the northwest and southeast of the mining area.

Ore bodies in the Dajing deposit occur mainly as vein-filling bodies. They are widely distributed in space, but the mineralization is generally weak. Most ore bodies form beltlike zones that are subparallel to the main orebodies. Wall-rock alteration is diverse. The main alteration types are silicification, sericitization, chloritization, and carbonation. Local biotitization is also present. Spatially, silicification and sericitization dominate in the central part of the deposit and are closely associated with Cu–Sn mineralization. In contrast, carbonation is dominant in the eastern and northern sectors and is mainly related to Ag mineralization. Mineralization in the deposit shows pronounced spatial and temporal zonation. In plan view, the mineralization changes outward from Cu–Sn mineralization in the central part to Pb–Zn–Ag mineralization in the peripheral areas. In section, the mineralization changes from shallow Pb–Zn–Ag mineralization to deep Cu–Sn mineralization. Controlled by regional structures and stratigraphic lithologies, the orebodies generally occur at elevations above 300 m. The principal mineralized interval is concentrated between 400 and 800 m. Orebody thickness is commonly 0.5–1.5 m. The orebodies typically occur in clusters and belts. Several types of dikes are developed in the deposit, including fine-grained rock, dacite porphyry, and spotted basalt. Their dominant strikes are NW and NWW, broadly consistent with the regional fault trend.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

48 valid minerals.

Rock Types Recorded