The Longtougang Cu－Zn deposit is located in the Northern Wuyi terrane. Orebodies are primarily hosted in glutenite of the Outangdi formation，the minority hosted in biotite－plagioclase granulite of the Zhoutanyan formation. The mineralization process can be divided into four stages：anhydrous skarn stage，hydrous skarn stage，sulfide－quartz stage and quartz－carbonate stage，Cu－Zn mineralization mainly occurs in the sulfide－quartz stage. Petrographic and microthermometric studies of fluid inclusions in hedenbergite and quartz of different mineralization stages show that there exist three types of fluid inclusions in the Longtougang deposit，namely two－phase liquid－rich(type Ⅰ)，two－phase gas－rich(type Ⅱ)and halite－bearing aqueous inclusions(type Ⅲ)，all of them can be recognized in the sufide stage while only typeⅠ inclusions developed in the anhydrous and quartz－carbonate stage. In order to discuss the evolution of the ore－forming fluids，the homogenization temperature(Th)and salinity of the three types of fluid inclusions have been measured by Linkam THMS600 and calculated formula，respectively. TypeⅠ inclusions in the anhydrous stage display Th of 345 ℃～418 ℃，and salinities of 3.2 wt.%～8.7 wt.% NaCl equivalent；fluid boiling occurred in the sulfide－quartz stage，which resulted in type Ⅱ and type Ⅲ inclusions share similar homogenization temperatures of 295 ℃～391 ℃ and 267 ℃～360 ℃，and contrasted salinities of 0.7 wt.%～3.4 wt.% and 31.6 wt.%～38.9 wt.% NaCl equivalent，respectively；type Ⅰ inclusions in the quartz－carbonate stage display Th of 234 ℃～274 ℃，and salinities of 0.2 wt.%～2.2 wt.% NaCl equivalent. Considering that the filed observation and various types of fluid inclusions，tectonic depression may be a vital factor for fluid boiling，which may also contribute to the late－stage sulfide deposition.
Wei Tao，Ni Pei*，Fan Mingsen，Zhang Xin，Liu Zheng.
Study on ore－forming fluids of the Longtougang Cu－Zn deposit，Jiangxi province[J]. Journal of Nanjing University(Natural Sciences), 2018, 54(2): 308
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