Polymetallic deposits are metal ore deposits that contain more than one useful metallic element or metal. Polymetallic deposits are commonly associated with hydrothermal activities in magmatic arcs, sedimentary rocks, and volcanic-hosted deposits. The vast majority of polymetallic deposits discovered and explored to date belong to the sediment-hosted type. The lode-type polymetallic deposits are veins or vein systems composed of base metal sulfides and/or high-grade metamorphic ore deposits formed in the metamorphic terrain. Due to the complexity of the formation process, the theoretical basis and applicable technologies of these deposits are still very immature. This leads to reservoir characteristics, structural features and metallogenic principles of polymetallic deposits with large differences.
The polymetallic deposits associated with the Laramide orogenic belt are an important type of magmatic arc-associated polymetallic deposits. These deposits are mined for the production of lead, zinc, copper, and other metals. The concentration of valuable metals in the ore is highly variable and may be subject to geological and physical processes, such as folding, faulting, and erosion. For example, the Cache Creek polymetallic ore deposit in British Columbia, Canada, is composed of massive sulfide lenses containing copper, zinc, lead, silver, and gold.
The Ronghe ore deposit is a typical tin-polymetallic deposit located in southwest China. Discovered in 1964, the Ronghe ore deposit has an orebody of fish-bone-shaped veinlets and lenticular lenses with a total length of over 50 km and total thickness of 3-6 m. It is hosted in medium-grade metamorphic rocks and is composed of quartz, pyrite, arsenopyrite, stannite, stannite-cassiterite, stannite-sulphide, and other minerals. This deposit has a distribution pattern of tin-polymetallic ores, with cassiterite as the main valuable mineral and wolframite, arsenopyrite, and pyrite as the important associated minerals. The ore contains minor amounts of lead and zinc.
Chimgan is a typical lode-type polymetallic deposit located in southwest Chinas Guangxi Province. Discovered in 1964, the Chimgan ore deposit consists of low-grade auriferous quartz veins, disseminated pyrite, and a few ore veins which contain copper, silver, and zinc. The ore veins with copper, silver, and zinc are distributed along the northeastern margin of the deposit in the host quartz-mica schist. The ore composition is mainly composed of pyrite, chalcopyrite, galena, and sphalerite, with minor amounts of tetrahedrite, marcasite, and electrum.
The Jinping polymetallic deposit is located in the Gaoligong Mountains of Yunnan Province, China. It is a typical volcanic-hosted polymetallic deposit and is composed of quartz-vein-type orebodies. The ore contains relatively high levels of gold, silver, lead, zinc, and other mineralized elements. The ore occurs in two basic types: massive and disseminated ore. The minerals in the pyrite-marcasite-chalcopyrite-pyrrhotite assemblage are distributed mainly in the form of disseminated ore, while the quartz-sulfide assemblage is mainly distributed in the form of quartz-vein ore.
The Jinping polymetallic deposit offers an ideal natural laboratory for conducting research on the formation and metallogenic tectonic environment of polymetallic deposits. It is believed that the metallogenic process of this deposit is closely related to the magmatic-hydrothermal activities associated with the Late Mesozoic subduction-related tectonic activities. The polymetallic orebodies are mainly hosted in Cretaceous volcanic rocks, and their formation process is dominated by hydrothermal activity.
In conclusion, polymetallic deposits are significantly different from other types of ore deposits due to their complexity of formation process, reservoir characteristics and structural features. These deposits are commonly found in magmatic arcs, sedimentary rocks, and volcanic-hosted deposits, and can be mined for a variety of different metals. The polymetallic orebodies are mainly hosted in Cretaceous volcanic rocks and are formed under magmatic-hydrothermal activity. The Jinping polymetallic deposit offers an excellent opportunity for studying the formation and metallogenic tectonic environment of polymetallic deposits.
