Xiaorequanzi Mine, Shanshan Co., Turpan, Xinjiang, Chinai

Regional Level Types
Xiaorequanzi Mine	Mine
Shanshan Co.	County
Turpan	Prefecture
Xinjiang	Autonomous Region
China	Country

Hydrothermal vein-type Cu-Zn deposit, located at the westernmost end of the Dananhu-Tousuquan arc. Although stratabound in Lower Carboniferous siltstone, fine-grained sandstone, tuff, and andesite of the Xiaorequanzi Formation, the orebodies mainly developed along a discordant NE- and ENE-trending zone. A NW-trending dome and a S dipping monocline define the structure of the deposit area. The major faults in the area are NE- to N-trending, but minor faults are trending NW. Several albite porphyry and dacite porphyry stocks and dikes are exposed in the mine area, and a gravity survey indicates that a granitic pluton may exist beneath. The present mine area is 2.5 km long by 2 km wide, and contains 22 orebodies, with the largest being 520 m long by 1 to 30 m wide, averaging 12.5 m. They are generally ENE-trending, dip to the SE at 30º-80º, and occur as lenticular and banded veins that formed along an anticlinal axis. The mineralization generally exhibits zoning, with copper ore in the shallower parts and zinc enrichment at depth. The major orebody is hosted by dark, carbon-rich, fine-grained sandstone along an array of shallowly-dipping fractures that are subsidiary to the more significant, steeply-dipping ore veins.

The Xiaorequanzi Formation is located north of the Xiaorequanzi Fault and forms a simple compound anticline with a curved termination. It consists of marine–continental volcanic clastic sedimentary rocks intercalated with volcanic formations. The lithology includes tuffaceous conglomerate, tuffaceous sandstone, tuff, andesite, and basaltic andesite, among others. It is the ore-bearing volcanic rock group of the Xiaorequanzi Cu deposit. The Xiaorequanzi Cu deposit contains a total of 102 known ore bodies, 30 of which are visible on the surface. The ore bodies generally measure 80–160 m in length and 60–120 m in width, with an average Cu grade of 1.13%. The total copper (Cu) content is 11.4 × 104 tons, and the zinc (Zn) content is 4.57 × 104 tons. The ore bodies of the Xiaorequanzi Cu mine are primarily veined and bedded, with the rich ore bodies mostly being irregular lenticular, saddle-shaped, or wedge-shaped, located in the disrupted por tion of the secondary fold structure. The mineralization process at the Xiaorequanzi Cu deposit can be divided into two main periods and three stages based on the characteristics of mineral paragenesis and vein crosscutting relationships, namely the VMS mineralization period (Stage I) and the epi thermal period. The epithermal period is characterized by quartz vein-type ore body cut ting through the earlier bedded ore body. The epithermal period is further subdivided into the quartz–chalcopyrite–pyrite (Stage II) and quartz–chalcopyrite–sphalerite (Stage III) veins.

The Xiaorequanzi VMS deposit is hosted in intermediate-felsic tuff, tuff sandstone, and minor dacite of the lowermost member of the Xiaorequanzi Formation (354–357 Ma). The Xiaorequanzi deposit consists of two ore zones (No. I and III) and one mineralized zone (No. II). The No. I ore zone is the most important ore zone dominated by copper mineralization, containing estimated resources of 114 kt @ 1.13 % Cu, 43 kt @ 0.52 % Zn, and 819 t Se, and significant Ag and Au. These orebodies strike approximately NS-trending, and dip NE at 40°, with a length of 800 m and width of 800 m. The No. III ore zone hosts mainly Zn-Pb orebodies, which strike approximately south and dip northeast at 10° to 60°. The distribution of orebodies was dominantly controlled by NW-trending faults and NE-trending contemporaneous faults. Their morphologies include lenticular, tabular, layered, veined, and irregular. Four ore types are reconstructed their paragenetic sequences, including (1) massive Zn-rich ores (stage I), (2) banded and massive Cu-rich ores (stage II-a and II-b), (3) veined and stockwork Cu ores (stage II-c), and (4) quartz-chalcopyrite and quartz-sphalerite-galena coarse veins (stage III). Among them, the early formed massive or banded Zn and Cu ores are mainly distributed in No. I ore zone, containing a significant ore resource at Xiaorequanzi (up to > 60 % Cu + Zn).

Galena from this deposit is strongly enriched in selenium (Liu et al., 2012).

Other Regions, Features and Areas containing this locality

References