Ore-forming fluids and metallogenic mechanism of the Xingjiashan skarn Mo deposit in Jiaodong, China

The Xingjiashan Mo deposit is currently a large skarn deposit in the Jiaodong metallogenic province. The hydrothermal activities of mineralization can be divided into four stages: early skarn stage (I), late skarn stage (II), quartz-sulfide mineral stage (III) and quartz-carbonate stage (IV). The characteristics of the fluid inclusions show that the inclusions can be divided into three types: liquid-rich inclusions (L), vapor-rich inclusions (V) and daughter mineral-rich inclusions (S). The results of Roman spectra study show that the volatile phases have H2S. In the early and late skarn stages, the homogenization temperatures peak value range from 375 degrees C to 450 degrees C, and the salinities have two ranges 14%similar to 15% NaCleqv and >30% NaCleqv. In quartz-sulfide mineral stage, the homogenization temperatures peak value range from 260 degrees C to 340 degrees C, and the salinities have two ranges 8%similar to 10% NaCleqv and >50% NaCleqv. In quartz-carbonate mineral stage, the homogenization temperatures peak value range from 170 degrees C to 200 degrees C, and the salinities ranges 8%similar to 10% NaCleqv and >50% NaCleqv. The values of delta(OH2O)-O-18, delta C-13(V-PDB), delta O-18(V-SMOW) and delta S-34 are 0.04 parts per thousand similar to 8.18 parts per thousand, -3.35 parts per thousand similar to-0.73 parts per thousand, 5.93 parts per thousand similar to 8.42 parts per thousand and 6.5 parts per thousand similar to 10.8 parts per thousand. These results indicate that the ore-bearing fluid in the early stage is characterized by high temperature and high salinity. The ore-forming fluids are mainly derived from magma. Magma water is major ore-forming fluid, with minor meteoric water in the late stage. Fluid boiling may be the mechanism of large-scale metallogenic precipitation.