摘要
The Fenghuangshan is a large Cu skarn deposit in the low-middle Yangtze metallogenic province. Based on microthermometric and isotopic (C, H, O, S, and Pb) studies, the authors discuss ore-forming fluids evolution and metal origin (s) of the Fenghuangshan Cu deposit. H2O-CO2 type fluid inclusions, which can be classified into liquid-rich, vapor-rich and daughter crystal-bearing subtypes, are ubiquitous in diopside, garnet, quartz and calcite. Laser Raman spectroscopic analysis indicates that liquid phase of fluid inclusions is H2O, and vapor phase is dominant by CO2, N2 and CH4. Homogenization temperature (Th) and salinity of fluid inclusions suggest three-stage history of ore-forming fluids, reflecting an evolution process from high-temperature and salinity at mineralization stage to low-temperature and salinity at post mineralization stage. Temperature decreasing and fluids boiling may be responsible for precipitation of large quantity of metals.