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Most skarns are found near the pluton or in lithologies containing at least some limestone. However, recent research has shown that neither a pluton nor limestone is necessarily required to form a skarn deposit. The newly discovered Bagenheigeqier Pb–Zn skarn deposit is located in NE China. The skarn and Pb–Zn orebodies occur in volcanic lithologies of the Baiyin'gaolao Formation and are controlled by NE–SW-trending faults. The nearest pluton is a granite porphyry, at a distance of 20–250 m from the orebodies. Five paragenetic stages at Bagenheigeqier are recognized: (I) skarn; (II) oxide; (III) early sulphide; (IV) late sulphide; and (V) late quartz–calcite. The fluid inclusions from stages II to V homogenized at temperatures of 402–452, 360–408, 274–319 and 167–212°C, respectively. The hydrogen and oxygen isotope compositions (δ18OH2O, –12.4‰ to +9.3‰; δDH2O, –156.5‰ to –99.1‰) indicate that the ore-fluids were primarily of magmatic origin, with the proportion of meteoric water increasing during the progression of ore formation. Sulphur isotope values (δ34SVCDT, 1.4–5.5‰), lead isotope values (206Pb/204Pb, 18.184–18.717; 207Pb/204Pb, 15.520–15.875; 208Pb/204Pb, 37.991–38.379) and the initial 187Os/188Os ratios of the pyrite (0.307 ± 0.06) suggest that the ore metals were derived from the granite porphyry and Baiyin'gaolao Formation. Re–Os dating of pyrite intergrown with galena and sphalerite yielded a well-constrained isochron age of 151.2 ± 4.7 Ma, which is coeval with the laser ablation – inductively coupled plasma – mass spectrometry zircon U–Pb age of 154 ± 1 Ma for the granite porphyry. The deposit was therefore formed during Late Jurassic time. [ABSTRACT FROM AUTHOR]

• The Shenshan deposit is a newly discovered skarn Fe–Cu deposit located in the Great Xing'an Range in Northeast China. • The Shenshan granodiorite is intimately associated with the Shenshan Fe–Cu mineralization in the Jurassic. • The host-rock granodiorite was derived from partial melting of thickened mafic lower crust. • The metals were derived from the granodiorite, whose formation was related to closure of the Mongol–Okhotsk Ocean during the Jurassic. The newly-discovered Shenshan Fe–Cu skarn deposit is located in the southern Great Xing'an Range of northeastern China. The mineralization occurs mainly in the exoskarn or marble wallrocks of the Permian Zhesi Formation, which were intruded by the Shenshan granodiorite and granite porphyry dykes. Molybdenite Re–Os dating yielded a weighted mean age of 160.2 ± 2.4 Ma (MSWD = 0.38), consistent with the LA–ICP–MS zircon U–Pb age of the granodiorite (161.6 ± 2.2 Ma; MSWD = 0.75), but significantly older than the granite porphyry dykes (132.8 ± 1.9 Ma; MSWD = 0.87). This suggests a coeval and causative relationship between the granodiorite and Fe–Cu mineralization. The Shenshan granodiorite has an adakite-like geochemical signature with high Sr contents (704–871 ppm), and high Sr/Y (46.79–80.21) and (La/Yb) N (17.54–31.13) ratios, but low Y (9.7–13.1 ppm) and Yb (0.70–1.18 ppm) contents. The granodiorite has relatively low contents of Mg (1.71–1.94 wt%), Cr (18–23 ppm), and Ni (4.1–9.0 ppm), and positive ε Hf (t) (−0.3 to 3.0, average 1.51), yielding two-stage model ages (T DM2) of 1.38–1.68 Ga (average 1.51 Ga). The results indicate that the parental magmas of the granodiorite were derived from partial melting of juvenile thickened lower crust with minor mantle-derived input. Meanwhile, the Shenshan granite porphyry dykes are high-K calc-alkalic and weakly peraluminous, with low MgO (0.21–0.24 wt%) and Mg# (19–21). The dykes exhibit HFSE (e.g., Nb, Ta) depletions and LILEs (e.g., Rb, K) enrichments, and strong to moderate negative Eu anomalies, indicating major continental crust-derived input in the magma source. Geochemical and Hf isotopic data compilation for granitoids across the Great Xing'an Range indicate that the mineralization at Shenshan was influenced by the south-dipping subduction of the Mongol–Okhotsk oceanic plate. The discovery of adakite-like rocks in the Shenshan Fe–Cu deposit, and the voluminous adakite-like rocks in the region, suggest that the Mesozoic Great Xing'an Range has considerable prospecting potential for Cu–Au–Mo deposits. [ABSTRACT FROM AUTHOR]