Genesis of the Bairendaba Ag-Zn-Pb deposit and its linkage to the Weilasituo Sn-polymetallic deposit, southern Great Xing’an Range, Northeast China

The Weilasituo–Bairendaba district in the southern Great Xing’an Range hosts one of Northeast China’s most representative polymetallic vein systems, yet the genetic relationship between its Sn-W-Li and Ag-Zn-Pb mineralization remains unresolved. This study integrates new geochronological, geochemical, and isotopic data to clarify the link between the Bairendaba Ag-Zn-Pb and Weilasituo Sn-polymetallic deposits and to constrain the evolution of their ore-forming fluids. The mineralization at Bairendaba comprises three main stages: an early Cu-Zn, a middle Pb-Zn-Ag, and a late Ag-rich stage. In situ LA-ICP-MS U-Pb dating of newly discovered wolframite from the early Cu-Zn stage yielded an age of 133.1 ± 3.3 Ma, consistent with the mineralization age of nearby Weilasituo Sn-polymetallic deposit (135–141 Ma), indicating a shared Early Cretaceous metallogenic event. Systematic trace-element variations in sphalerite (e.g., decreasing In, Se; increasing Cd, Ge; rising Zn/Cd and Ga/In ratios) and wolframite (decreasing Nb-Ta concentrations with distance) from Weilasituo to Bairendaba record progressive fluid cooling and distal metal precipitation from a common magmatic-hydrothermal system. H-O isotope data from Weilasituo to Bairendaba (δ 18 O fluid : 5.3 to −6.3‰; δD: −125.9 to −110.5‰), confirm that the hydrothermal fluids evolved from magmatic-dominated (early high-temperature and salinity) to meteoric-influenced (lower-temperature and salinity) conditions. Carbon and S isotopes (δ 13 C = -18.2 to −6.9‰; δ 34 S = -3.3 to + 0.3‰) of Bairendaba further indicate late-stage organic carbon input from host gneiss and a uniform magmatic sulfur source. Collectively, the Bairendaba deposit is classified as a medium-temperature magmatic-hydrothermal vein system, genetically linked to the Weilasituo deposit. It represents the distal, medium-temperature expression of a unified Sn-W-Li-Cu-Pb-Zn-Ag magmatic–hydrothermal system centered on the Weilasituo intrusion, characterized by temperature-controlled mineralization zonation across the district.