Geochronology, geochemistry, Sr–Nd–Hf isotope composition of the late Permian adakite in West Ujimqin, Inner Mongolia: petrogenesis and tectonic implications

We report herein on new zircon U–Pb ages, the major and trace elements of whole-rock, Sr–Nd–Hf isotope composition for adakitic intrusives collected from West Ujimqin district in Southeast region Central Asian Orogenic Belt (CAOB). These data provide important constraints petrogenetic evolution geodynamic setting late Permian magmatism CAOB. The dating shows that ages Seerbeng pluton Nuhetingshala are 255.3 ± 0.71 254.4 1.2 Ma, respectively, which signifies these products magmatic activity Permian. characterized by high levels Sr (Sr ≥ 741 ppm), low Y, Yb, Sr:Y ratios, strongly fractionated rare earth (10.3 < La N /Yb 22.5), is similar to features adakite. zircons exhibit positive Hf values (+8.1 +13.3), young two-stage model vary 430 760 Ma. ε Nd (t) ( 87 Sr: 86 Sr) i indicate granite derived partial melting subducted oceanic slab. level Mg # [100 × Mg/(Mg + Fe) atomic number] abundant Cr–Ni melts interacted with olivine rocks mantle. Considering results regional rock assemblies, we conclude Paleo-Asian Ocean had not yet completely closed Permian, northward subduction continued, slab possibly breaking off.