The Bozhushan batholith consists of metaluminous tin-barren medium-grained monzogranites (magmatic episode 1) and peraluminous tin-bearing fine-grained monzogranites (magmatic episode 2).
There are more than 70 ore bodies in the mining area, and ore body V1 accounts for >90% of the total ore reserves. Ore body V1 strikes 100° and dips 190° to the SW (with an angle of 15–20°), and has a strike length of 4.8 km, depth of dip up to 2.5 km (average = 1.31 km) and maximum thickness of 33.62 m (average = 5.65 m).

The ore field is about 25 km2 and consists of 40 lenses grouped into five ore blocks including Baiyang, Miwei, Chuanxindong, Duimenshan and Awei. Economically, it has large metal reserves including Ag (>7000 t), Zn (172 Mt), Pb (110 Mt), and Sn (8.6 Mt) with a certain amount of dispersed metals such as In (10.2–152 μg/g), Cd (0.5 μg/g).
Based on spatial occurrence, morphology, and ore mineral assemblage, orebodies are classified into three types: (1) stratiform, lenticular, and veined Ag–Pb–Zn–Sn sulfide orebodies, accounting for over two-thirds of the Ag–Pb–Zn–Sn reserves of this deposit, occur in the Tianpeng Formation and Longha Formation; (2) laminated Cu-sulfide orebodies, comprising of chalcopyrite, pyrrhotite, pyrite, occur at faulted zones along the contact with granitic plutons (comprising of porphyritic biotite monzogranite and tourmaline bearing monzogranite considered to be A-type granite); (3) lenticular Sn-bearing skarn orebodies, mainly comprising of magnetite and cassiterite in the Duimenshan Block, occurr along the contact between granitic plutons and the middle Cambrian carbonate rocks. Geometrically, ore bodies are lenses with length between 50 and 2500 m, and thickness between 0.7 and 30 m.
Paragenetic sequence consisting of skarnization and hydrothermal mineralization episodes for the Bainiuchang Zn-Sn polymetallic deposit. The skarnization episode includes the prograde, late retrograde and oxide stages: The prograde stage (a1) comprises abundant garnet and diopside, the retrograde stage (a2) comprises tremolite, vesuvianite, and epidote, and the oxide stage (a3) comprises magnetite and cassiterite. In addition, the hydrothermal mineralization episode includes: the cassiterite–sulfide stage (b1) comprising of cassiterite, arsenopyrite, pyrrhotite, marcasite, chalcopyrite, stannite, sphalerite I, galena, boulangerite, and the carbonate–sulfide stage (b2) comprising of sphalerite II, galena, siderite and calcite.

The Bainiuchang deposit, located at the northwestern end of the Bainiuchang-Bozhushan anticline, is structured by NW-, NE-, and NS-trending faults, hosted in Cambrian clastic-carbonate substratum and Devonian hanging-wall rocks. It comprises NW synclines, NW/NE anticlines, diabase dykes, and the Bozhushan concealed granitoid, hosting > 70 orebodies concentrated in five oreblocks (Baiyang, Duimenshan, Miwei, Chuanxindong, Awei). Orebody types include: (1) fault-hosted stratiform/lenticular/veined Ag-Pb-Zn-Sn sulfides, (2) granitoid contact-related laminated cassiterite-Cu sulfides, (3) mid-Cambrian carbonate-granitoid contact skarns, and (4) Sn-rich carbonate veinlets. Previous studies have dated Types 1‒3 mineralization to ca. 87 Ma, whereas Type 4 (arsenopyrite-calcite-dolomite-cassiterite mineral assemblage) has been less studied.

Reserves: 6,740 t Ag@95g/t; 0.09 Mt Sn@0.12%; 1.72 Mt Zn; 1.09 Mt Pb; ~1000 t In

Note:
Not to be confused with the Bainiuchang lead-zinc deposit of Qiaojia County, Zhaotong Prefecture.

Other Regions, Features and Areas containing this locality

References