Metallogenic age, material sources, and ore-forming process of the Donggou VMS-type zinc deposit in the Qimantag Area, East Kunlun Orogenic Belt

The Donggou zinc deposit is the first discovered volcanogenic massive sulfide (VMS)-type lead–zinc deposit in the East Kunlun orogen, holding significant scientific value and economic potential. As a newly identified deposit type in the region, key scientific issues such as its metallogenic age, sources of ore-forming materials, ore-forming conditions, and genetic mechanism remain unclear. This study systematically analyzes the major and trace element compositions of sphalerite from different ore-forming stages within the main mineralization period, the in situ S-Pb isotopic characteristics of major metallic sulfides, and zircon U-Pb dating of the host rocks. The aim is to delineate the ore-forming process and elucidate the genetic mechanism of the deposit. Results indicate that the main mineralization period of the Donggou deposit can be divided into three stages: stockwork stage (I), massive sulfide stage (II), and laminated stage (III). The trace element compositions of sphalerite from these stages (Sp1, Sp2, Sp3) show significant differences: Sp1 is relatively enriched in Cu, In, Se, and Co; Sp2 is enriched in Mn, Ag, As, and Pb; and Sp3 is characterized by enrichment in Sb and Ga. Temperature estimates based on the GGIMFIS geothermometer for sphalerite are 314-361°C (avg. 334°C) for Sp1, 296-336°C (avg. 317°C) for Sp2, and 286-334°C (avg. 308°C) for Sp3. Corresponding sulfur fugacity (lg f s 2 ) ranges are −6.79 to −4.93 for Sp1, −7.60 to −5.89 for Sp2, and −8.10 to −6.23 for Sp3. These indicate that the ore-forming fluids were generated under medium‑ to high‑temperature and relatively high sulfur fugacity conditions. From early to late mineralization, temperature remained generally stable, while sulfur fugacity gradually decreased. In situ δ 34 S values of sulfides (−3.59‰ to 6.24‰) suggest that sulfur was primarily derived from the degassing of a shallow magma chamber or the leaching of wall rocks, with minor incorporation of seawater sulfate sulfur formed via thermochemical sulfate reduction (TSR). Lead isotope compositions of galena ( 208 Pb/ 204 Pb = 37.980–38.021, 207 Pb/ 204 Pb = 15.575–15.613, 206 Pb/ 204 Pb = 18.210–18.261) display characteristics of a mixture derived from basement and wall rocks. Zircon U-Pb dating of the host rock yields an age of 446 ± 1.5 Ma, indicating that the deposit formed during the Late Ordovician subduction of the Qimantag Ocean. In summary, this study delineates for the first time the metallogenic age, material sources, and evolution of physicochemical conditions of the ore-forming fluids for the Donggou VMS-type zinc deposit, providing a detailed reconstruction of the ore-forming process. These findings are significant for understanding VMS-type mineralization in the East Kunlun orogen and for guiding regional mineral resources exploration.