Sulfur and lead isotope geochemistry of sulfide minerals from the Yushui copper deposit, eastern Guangdong, South China

The Yushui volcanogenic massive sulfide (VMS) copper deposit in eastern Guangdong, South China, is distinguished by two discrete mineralization events: a Carboniferous stratiform ore system (ca. 308 Ma) and a Jurassic vein-type overprint (ca. 163 Ma). In situ sulfur and lead isotope analyses (LA‑MC‑ICP‑MS) were conducted on sulfides from both ore types to constrain sulfur and metal sources and hydrothermal system evolution. Sulfur isotopes (δ 34 S = − 23.88‰ to + 4.01‰) show systematic variations: early exhalative and stockwork ores record significant bacterial and thermochemical reduction of seawater sulfate, whereas main‑stage massive and banded ores approach magmatic sulfur values (0‰ to + 3‰). Vein‑type ores yield δ 34 S indicative of a dominant magmatic source linked to Jurassic igneous activity. Lead isotopes form three linear groups corresponding to Carboniferous VMS mineralization, Jurassic vein‑type overprint, and host volcanic rocks. Lead in stratiform ores was largely leached from basement crust with minor magmatic input, while vein‑type ores predominantly inherited lead from pre‑existing stratiform ores in a closed system. These results confirm a two‑stage genesis: (1) shallow‑marine seafloor hydrothermal sedimentation forming primary VMS ore bodies at ∼ 308 Ma; (2) Jurassic magmatic‑hydrothermal reworking and superimposition generating vein‑type ore bodies at ∼ 163 Ma. This study highlights the utility of in situ S–Pb isotopes in unravelling polyphase ore‑forming processes in VMS deposits modified by later tectono‑magmatic events.