Metal Source and Fluid Evolution in Xiaojiashan Gold Deposit in Northeastern Hunan, China: Implications of Rare Earth Elements, Fluid Inclusions, and Pyrite S Isotopic Compositions

The material source and the evolution of ore-forming hydrothermal fluids Xiaojiashan gold deposits remain controversial. We carried out a mineralogical characteristics analysis, trace elements sulfur isotope composition fluid inclusion microthermometry in order to explore sources, conditions, process this deposit. Gold mineralization can be divided into three stages: quartz-pyrite stage, quartz-polymetallic sulfide quartz-ankerite stage. This deposit was probably formed under following conditions: temperature 122–343 °C salinity 0.8–11.4 wt% (NaCl). It inferred that were early metamorphic–hydrothermal (Stage I) late magmatic–hydrothermal (Stages II III), characterized by medium–low based on S composition. decreased during mineralization, which caused involvement groundwater. chondrite-normalized element patterns ores are similar host rocks Lengjiaxi Formation, indicating materials sourced from Formation. isotopes indicated magmatic components also provided Stages III.