Genesis of the Changlingzi Zn–Pb deposit in the southern Great Xing’an Range, northeastern China: constraints from fluid inclusions and H–O–S–Pb isotope systematics

Abstract

The Changlingzi Pb–Zn deposit is located in the southern Great Xing’an Range metallogenic belt of Northeast China. This deposit experienced two types of mineralization including skarn (ore block I) and hydrothermal vein (ore block II), and their orebodies are hosted mainly in the Lower Permian Zhesi Formation. The hydrothermal mineralization is classified into two metallogenic periods: skarn (stage 1) and sulfide (stages 2, 3, and 4). The skarn period affected only the ore block I, whereas the sulfide period similarly affected the two ore blocks. Fluid inclusion studies indicate that the ore-forming fluids during the early stage were medium- to high-temperature, high-salinity heterogeneous NaCl–H2O fluids, and that they eventually evolved to low-temperature, low-salinity homogeneous NaCl–H2O fluids by late stage. Studies of the hydrogen and oxygen isotope compositions (δ18OH2O = −13.85‰ to 3.95‰, δDH2O = −132.8‰ to −102.7‰) show that the ore-forming fluids gradually evolved from magmatic water to meteoric water. Sulfur and lead date suggest that the ore-forming materials were probably derived from deep magma and the Permian strata. Although our data show that ore blocks I and II, in terms of genesis, were skarn- and medium- to low-temperature hydrothermal vein-types, respectively, the ore-forming fluids of both ore blocks were the same period, and the differences in mineralization type can be related to the wall rocks.