Fluid inclusions in gold-bearing quartz veins of Jiaojia-type gold deposits in the Jiaodong, Shandong

Well-known Jiaojia-type gold depozed are characterized by fractured altered rock-type gold mineralization. However, big gold-bearing quartz veins have also been found there. The fluid inclusions in this kind of gold-bearing quartz vein are mainly two-phase liquid-vapor inclusions with subordinate LCO2 inclusions. The main and minor homogenization temperature peaks are about 200 and 290℃ respectively. The salinities range mainly from 2 to 10 wt% NaCl. The pressures estimated by LCO2 inclusions range from 20 to 38 MPa. The dominant component of the vapor phase of the inclusions in quartz is H2O, and next comes CO2. The ion composition of the inclusions in pyrite generally shows Na+K+Ca2+ and SO42-Cl-F- and the ion composition of the inclusions in quartz generally shows K+Na+Ca2+(Na+K+Ca2+ in deformed quartz)and SO42-Cl-F-. All the above features of the gold-bearing quartz veins in Jiaojia-type gold deposits are similar to those of the gold-bearing quartz veins in Linglong-type gold deposits but somewhat different from those of the fractured altered rock-type gold mineralization in the same Jiaojia-type gold deposits. This difference may be due to the following: gold-bearing quartz veins are formed by filling, fractured altered rocks-type gold mineralization results from emplacement.