The Baogutu copper deposit, a newly-discovered middle-sized porphyry copper deposit, is located in the West Junggar region of Xinjiang, NW China. Baogutu is associated with a Late Carboniferous intrusive complex that was emplaced into Lower Carboniferous volcano-sedimentary strata. The intrusive complex comprises main-stage diorites and minor late-stage diorite porphyries. Their intrusive activity occurred in 313.0±2.2Ma to 312.3±2.2Ma based on U–Pb zircon SIMS analyses. Molybdenite separated from ore-bearing quartz veins yields Re–Os model ages from 309.4±4.4Ma to 314.1±4.5Ma with a weighted mean age of 312.4±1.8Ma. Biotites, separated from fresh diorite and hydrothermal breccias in main-stage diorites, yield 40 Ar/ 39 Ar plateau ages of 308.26±1.88 and 305.69±1.76Ma, respectively. These dates obtained from three independent dating techniques constrain the ore-forming age of the Baogutu deposit.Stable isotopes (H, O, S) and radiogenic isotope (Pb) have been used to discriminate the sources of the ore-forming fluid at Baogutu. The δ 18 O (1.14–1.74‰) and δD (−74‰ to −98‰) data indicate that the water of the ore-forming fluids was derived from magmatic water. The δ 34 S values (−0.24‰ to +0.4‰) show that the sulfur isotope composition of the ore fluids is characterized by magma sulfur. Lead isotope compositions ( 206 Pb/ 204 Pb=17.92–18.89, 207 Pb/ 204 Pb=15.45–15.62, 208 Pb/ 204 Pb=37.68–38.36) indicate that the lead of the ore fluids is derived from the mantle. These data confirm the occurrence of a Cu–Au–Mo mineralizing event at Late Carboniferous in the Baogutu region and the ore-forming fluids are mainly derived from the mantle. The event is inferred to be associated with Late Carboniferous Junggar oceanic crust subduction.