Spatiotemporal distribution, geological characteristics and metallogenic mechanism of tungsten and tin deposits in China: An overview

Abstract

Tungsten and tin are important strategic and critical mineral resources, as well as one of China’s most abundant mineral resources. Their distribution is mainly concentrated in the South China block, followed by the Kunlun-Qilian-Qinling-Dabie orogenic belt, the Tianshan-Xingmeng orogenic belt, and the Tibet-Sanjiang orogenic belt. The tungsten and tin resources in South China are mainly concentrated in the Nanling tungsten-tin metallogenic belt, the northern Jiangxi-southern Anhui tungsten metallogenic belt, the Youjiang-Guibei tin metallogenic belt, and the southeast coastal tungsten-tin metallogenic belt. The formation of tungsten and tin deposits in China spans a large period of time, from Proterozoic to Cenozoic, but the Mesozoic Yanshanian mineralization is the most important. There are five main types of primary tungsten-tin deposits in China, namely, porphyry, greisen, skarn, quartz vein, and cassiterite-sulfide. In addition, there are also other types such as altered granite, hydrothermal breccia, and low-temperature hydrothermal vein. Many tungsten-tin deposits are often not of a single genetic type, and multiple mineralization types commonly co-exist in a deposit. Most of the granitoids associated with tungsten mineralization are thought to be S-type granite derived from partial melting of continental crustal materials, while the granitoids associated with tin deposits include I-type and A-type in addition to the S-type granite. Crust-mantle interaction plays an important role in generation of the Sn-bearing granites. Nd-Hf isotope studies show that beside the Sn-bearing granites, some W-bearing granites also have mantle-derived contributions. Whether it is W-bearing or Sn-bearing granite, a highly evolved feature is often more favorable for mineralization. The composite granitoids in South China are closely related to multiple tungsten-tin mineralization. Many tungsten and tin deposits in China are often co-produced with mineralization of other rare metals. According to the combination of ore elements, they mainly include the following three types: W-(Sn)-Be (including Sn-Be), W-(Sn)-Nb-a (including Sn-Nb-Ta), and Sn-Li-Rb-Nb-Ta. All of them are closely related to highly evolved peraluminous granites. The source of ore-forming fluids in most tungsten-tin deposits is closely related to magmatic hydrothermal activity, and some deposits also have characteristics of multi-source fluids. The temperature and salinity of ore-forming fluids vary widely, and the composition of the fluid system is also complex in many cases. Oxygen fugacity plays an important role in the transportation and precipitation of tin, but such an effect on tungsten is still in debate. The formation of many tungsten-tin deposits is generally controlled by a number of factors, such as temperature dropping, fluid mixing, fluid immiscibility, fluid boiling, and water-rock interaction.