Petrographic, microthermometric and laser Raman spectroscopic studies were carried out on fluid inclusions in quartz from metamorphic rocks-amphibolite-and gold ores in the Jiapigou Group in the Jiapigou area. The results show that three types of primary fluid inclusion occur in quartz from ores: aqueous phase, CO2-bearing phase and CO2 phase. The ore-forming fluids were once the immiscible NaCl-H2O-CO2 system and the various types of inclusion are characterized by homogenization temperatures ranging from 157. 2 to 440 degrees C, salinities between 1. 8 and 11.6% NaCl equiv and fluid densities from 0. 54 to 0. 96g/cm(3). The fluid inclusions in quartz from metamorphic rocks are mainly daughter crystal-bearing polyphase ones with homogenization temperatures from 260 to 480 degrees C, salinities from 36. 5 to 54.8% NaCl equiv and fluid densities from 1. 06 to 1. 17g/cm(3), reflecting that the metamorphic fluids were a homogenous NaCl-H2O system with medium temperatures, high salinities and high densities. The appreciable difference between the ore-forming fluids and metamorphic fluids suggests that the ore-forming fluids of the gold deposits in the area are not of Archean metamorphic origin. According to the above mentioned, combined with the latest hydrogen and oxygen isotopic analyses and mineralization age data of the fluid fluids, the authors believe that the ore-forming fluids were mainly derived from magmatic hydrothermal fluids and that the gold deposits are Mesozoic magmatic hydrothermal ones.
