Genesis and age of gold mineralization in the Shipenggou gold deposit, Jilin province, NE China: Evidences from Rb-Sr geochronology, H-O-S isotopes and trace element geochemistry of pyrite

• The Shipenggou is a magmatic-hydrothermal lode gold deposit adjacent to the Jiapigou ore district. • Gold mineralization occurred at 165 ± 5 Ma and was related to the subduction of Paleo-Pacfic Plate. • The ore-forming fluids were sourced from mantle-derived magmatic water. • The ore-forming materials exhibit a hybrid source involving both mantle and crustal components. The Shipenggou gold deposit is situated in the northeastern margin of the North China Craton (NCC), adjacent to the Jiapigou ore district. This study integrates pyrite Rb-Sr geochronology, H-O isotope analyses, in-situ sulfur isotope analyses of sulfides, and pyrite trace element analyses to constrain the genesis and age of the Shipenggou deposit, thereby advancing our understanding of regional gold metallogenic processes. Ore bodies in the Shipenggou deposit primarily occur as gold-bearing quartz veins hosted within the biotite-plagioclase gneiss of the Sandaogou Formation, structurally controlled by NEE- and NNE-trending brittle-ductile structures. The δ 18 O H2O (–3.6 to –6.2‰) and δD (–87.3 to –69.2‰) values suggest that the initial ore-forming fluids were predominately derived from a magmatic source, with subsequent meteoric water incursion during the late stages of mineralization. Sulfur isotope data of sulfides (δ 34 S = 4.62 to 8.19‰) indicate that sulfur is primarily sourced from a mantle-derived reservoir, with incorporation of crustal components through wall-rock assimilation. Pyrite initial 87 Sr/ 86 Sr signatures (0.71026 to 0.71044) imply a hybrid source for the ore-forming materials involving both mantle and crustal components. Variation in pyrite trace element compositions reflect a gradual decrease in temperature and a slight increase in oxygen fugacity (ƒO 2 ) of hydrothermal fluids throughout the mineralization process, although conditions remained predominantly reducing. Pyrite samples from polymetallic sulfide-quartz veins yield a well-constrained Rb-Sr isochron dating result of 165 ± 5 Ma, precisely determining the gold mineralization age in the Shipenggou deposit. These findings indicate that the Shipenggou deposit is of magmatic-hydrothermal origin, genetically linked to the Middle Jurassic subduction of the Paleo-Pacific Plate.