Study on fluid inclusions of the sedimentary-exhalative system (SEDEX) in Xitieshan lead-zinc deposit
青海锡铁山铅锌矿床喷流沉积系统(SEDEX)成矿流体研究

The Xitieshan lead-zinc deposit is located at the northern margin of the Qaidam basin, Qinghai Province and has a complete marine sedimentary-exhalative system. Our preliminary study of ore-forming fluids shows that fluid inclusions in quartz from altered stockwork rocks that represent the pipe facies have a wide range of temperature and salinity. The intense fluid activities are characteristics of the pipe facies of the exhalative system. Fluid inclusions in carbonates near the unstratified ore bodies hosted in thick-bedded marble which represents vent-proximal facies are large in size and have moderate to high temperature. They represent unerupted sub-seafloor fluid activity. Fluids in altered stockwork rocks and carbonates have similar H2O-NaCl-CO2 system and higher temperature, both belonging to the sedimentary-exhalative system. The fluids migrate from the pipe facies to the unstratified ore bodies. The homogenization temperature and freezing temperature of sluid inclusions from stratified ore bodies are similar with unstratified ore bodies, but lack the inclusions of great gas/liquid ratio and containing daughter minerals and CO2 component in fluid and the homogenization temperature is slightly lower. That is to say their fluid is continuum. The ore-forming fluid is come from vent-proximal facies that blow out from sea bottom and have moved to southeast of mining area and indicate that there is a huge ore-forming potential southeastwardly however.