YE Lin1, BAO Tan1,2, LIU Yu-ping1, ZHANG Qian1, WANG Xiao-juan1,2, HE Fang1,2, WANG Da-peng1, LAN Jiang-bo1
(1. State key Lab. of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. University of the Chinese Academy of Sciences, Beijing 100049, China)
Abstract: As one of the three largest Sn-polymetallic deposits in China, Dulong ore deposit is located in the southern Laojunshan Sn-Zn-W polymetal mineralization area in south-eastern Yunnan Province, China, and is characterized by complicated geological process, mineralization, and mineral assemblages. Research on mineral assemblages of the deposit indicates four mineralization stages from early to late; (a) skarn stage, the mineral assemblages are dominated by anhydrous skarn (e.g. garnet and diopside) in the early skarn stage and hydrous skarn (e.g. actinolite, epidote, chlorite and vesuvianite ); (b) oxide stage, magnetite, cassiterite and scheelite formed in quantity at the stage; (c) sulphide stage, the mineral assemblages are composed by pyrrhotite, pyrite, chalcopyrite and molybdenite at the early higher temperature stage and sphalerite with minor galena at later lower temperature stage; and (d) carbonate stage, the calcite vein with galena, which occurs around the surface, formed at the stage. The vertical zoning of ore-forming elements and skarn assemblages are related to the distance of concealed granite, corresponding with the typical skarn type deposit, and it is suggested that Dulong deposit is a magmatic hydrothermal skarn type deposit related to Yanshanian granite. The research on fluid inclusion shows that the salinity of ore-forming fluid decreased gradually from the early to the late stage, and the major cassiterite, scheelite and magnetite mineralization formed at high-intermediate temperature and chalcopyrite, sphalerite and galena formed at intermediate-low temperature. It is suggested that the fluid boiling, which caused by the loss of pressure quickly and mixing with meteoric water, is the key mineralization mechanism for ore-forming elements in abundance. The research provides a new geological and geochemical evidence for understanding the mineralization of Dulong Sn-Zn polymetal ore deposit.
Keywords: Dulong Sn-Zn polymetal ore deposit; mineralization stage; Ore-forming fluid; magmatic hydrothermal skarn type deposit
E-mail：yelin@vip.gyig.ac.cn
ACTA MINERALOGICA SINICA Vol. 36, No. 4, 2016, Page 503-509
