Tungsten deposits in the Middle-Lower Yangtze Metallogenic Belt, China

The Middle-Lower Yangtze Metallogenic Belt ( MLYB) is one of the most important Fe-Cu-Au-polymetallic metallogenic belts in eastern China. The newly discovered tungsten mineralization in the MLYB in recent years has raised a new topic for the study of this metallogenic belt. Compared with the study of copper, gold and iron ore deposits in the MLYB, the study of tungsten deposits in the metallogenic belt is obviously poor. Large scale tungsten deposits, including Donggushan deposit, Ruanjiawan deposit, Guilinzheng deposit and Gaojiabang deposit, are located in this belt. In this paper, we summarized the geological characteristics, geochronology and geochemistry of the tungsten skarn deposits and tungsten mineralization in skarn copper and iron deposits in the MLYB and investigate the metallogenic processes for the tungsten mineralization. Through detailed field investigations and a review of published data, we conclude that the magmatism and mineralization of tunsgten deposits in the MLYB can be divided into three stages of 146 similar to 143Ma, 127Ma and 97Ma, which are characterized by multiple periods of time. Whether accompanying or after the main metallogenic periods of copper (140Ma) and iron (130Ma , tungsten metallogenic events do have occurred. The epsilon(Nd) (t) data and Sr-87/Sr-86 data of scheelite in tungsten deposit indicated the ore-forming material of the deposits were from the Dongling basement or Jiangnan basement. The tungsten ore-related intrusions in the MLYB are felsic rocks, with very low epsilon(hf) (t) value and Zr/Hf and K/Rb ratios, indicating that the tungsten magmatic rocks were generated by remelting of the ancient crustal materials and then undergone full magmatic differentiation. Combining the previous works that the ore-related magma of copper deposits are the feldsic mixed magma enriched by partial melting of lithospheric mantle and thickened lower crust, the ore-related magma of iron deposits are the basic magma enriched by partial melting of lithospheric mantle, we conclude that the source region is the key reason for the mineralization differences in the MLYB. The intra-continental subduction during the Yanshanian Period causing reworking of the basements is the dominant mechanism for large-scale magmatism and mineralization in this belt.