Kangjiawan Pb-Zn-Ag-Au deposit, Shuikoushan ore field, Changning Co., Hengyang, Hunan, Chinai

Regional Level Types
Kangjiawan Pb-Zn-Ag-Au deposit	Deposit
Shuikoushan ore field	Ore Field
Changning Co.	County
Hengyang	Prefecture-level City
Hunan	Province
China	Country

The Kangjiawan deposit is a representative hydrothermal Pb-Zn-Ag-Au deposit in this region. The orebodies consist mainly of pyritic Pb-Zn ores. Silver minerals are associated with Pb-Zn mineralization. Ag-bearing Pb-Zn ores in the deposit are characterized by Ag > Cu > Sb content. Silver occurs mainly as silver minerals, such as minor argentian tetrahedrite, freibergite and abundant polybasite-arsenpolybasite, pearceite and pyrargyrite-proustite, and all are hosted in galena. The assemblages of silver minerals found in the major orebodies change from the southern to the northern part, from argentian tetrahedrite + pearceite + arsenpolybasite + pyrargyrite-proustite in the south, to polybasite-arsenpolybasite + pyrargyrite in the center, and to pyrargyrite in the north.

A total of 61 Pb–Zn vein-type/lensoidal orebodies have been delineated at Kangjiawan, among which seven are more important (I–VII). Orebodies I–V were developed in the silicified breccia zones in/near the Jurassic-Permian unconformity, while orebodies VI and VII occur along the F22 hanging-wall in the Lower Permian argillaceous limestone. The orebodies generally strike N-S and are mainly west-dipping (locally east-dipping) with an angle of 15–40°. Orebody IV-3, the largest orebody at Kangjiawan (0.443 Mt contained Pb + Zn metal, accounting for 50.6 % of the total metal reserve at Kangjiawan, is 859 m long, 33–174 m wide, and 0.14–19.43 m (avg. 6.0 m) thick.

Metal reserves of about 220,000 tons of Pb, 240,000 tons of Zn, 750,000 tons of sulfur, 2 tons of Au, and 15 tons of Ag, with average ore grades of 3.92% for Pb, 4.50% for Zn, 2.68 g/t for Au, and 86.80 g/t for Ag.

The mineralization in the Kangjiawan Au deposit can be categorized into three discernible stages, marked by the presence of: Quartz-pyrite (Stage I), Quartz − gold-bearing pyrite − galena − sphalerite (Stage II), and Calcite − gold-bearing pyrite − galena − sphalerite (Stage III). The Lower Permian Dangchong Formation (muddy limestone) and the Lower Permian Qixia Formation (limestone) are the major ore-hosting layers.

Fifty-six veined Pb-Zn-Au orebodies occur in the Kangjiawan deposit. Three types of hydrothermal alteration zones (i.e., the skarn zone, breccia and silicification zone, and carbonatation zone) have been identified. The skarn zone is distributed in an area of approximately 700 m below the surface, and is characterized by a small amount of disseminated andradite, magnetite, pyrite and chalcopyrite. The andradite commonly suffered from intense low-temperature alteration with the occurrence of chlorite and calcite. The breccia and silicification zone developed in the fracture zone of the Permian detrital rocks and carbonate rocks. The silicified breccia was cemented by quartz-pyrite veins and veined Pb-Zn orebodies. The carbonatation zone extensively occurred in the carbonate rocks of the Qixia Formation, with re-crystallized calcite veins cutting the pre-existing Pb-Zn orebodies. Recently, skarn mineralization has been newly reported in the Kangjiawan deposit. It is confirmed that the Kanjiawan deposit should belong to the distal skarn Pb-Zn-Au-(Ag) metallogenic system.

Other Regions, Features and Areas containing this locality

References