Geochemistry and geochronology of the Dongshanwan porphyry Mo–W deposit, Northeast China: Implications for the Late Jurassic tectonic setting

•Dongshanwan porphyry Mo–W deposit occurs at the eastern segment of the CAOB.•Dongshanwan mineralization is related to the granite porphyry.•The Late Jurassic granite porphyry indicates A-type geochemical characteristics.•The Late Jurassic magmatism and mineralization took place in the eastern CAOB.

The Dongshanwan porphyry Mo–W deposit is located in the southern segment of the Da Hinggan Mountains of the eastern segment of the Central Asia Orogenic Belt. More than 95% of the mineralization occurs within the Dongshanwan granite porphyry, with a small part being hosted within quartz veins that crosscut the Late Permian strata. Zircon U–Pb age measurements indicate that the Dongshanwan granite porphyry has a 206Pb/238U age of 151.4 ± 0.8 Ma. Three molybdenite samples from the Dongshanwan deposit were selected for Re–Os isotope measurement to define the mineralization age of the deposit. These yielded Re–Os model ages of 149.3 ± 2.3 to 155.4 ± 3.3 Ma. Based on analyses of major and trace elements and Hf isotopes, the Dongshanwan porphyry is characterized by low Sr and high Y values, exhibiting strong negative Eu anomalies (δEu = 0.01–0.04), indicating post-collisional (A-type) geochemical characteristics. The Hf isotopic composition of the Dongshanwan porphyry (εHf(t) = +5.5 to +9.2) indicates that both juvenile crustal sources and depleted mantle contributed to their origin. The regional geological setting, when combined with the geochemistry of the Dongshanwan porphyry, probably indicates that the granite porphyry derives from crustal root melting during lithospheric delamination in northeast China caused by the rollback of the paleo-Pacific plate.