Geochemistry and Isotopic Characteristics of Apatite and Zircon From Late Jurassic Granites in the Jiaobei Terrane, East China: Implications for Petrogenesis and Geodynamic Setting

The North China Craton (NCC) was stable for more than 2.0 Gyr before a Jurassic–Cretaceous large-scale lithospheric thinning event, but the geodynamic setting during early phases (Late Jurassic) of NCC reworking remains controversial. We present new petrological and whole-rock geochemical data, zircon apatite geochemistry, U–Pb ages, O isotopic Sr–Nd data two Late Jurassic granite (Linglong Luanjiahe) from Jiaobei terrane, southeastern NCC. LA-ICP-MS U-Pb dating suggests that Linglong formed about 6 Myr earlier Luanjiahe (158 Ma vs 152 Ma), after inception paleo-Pacific plate subduction. High U/Yb ratios, high δ 18 values [7.89 ± 0.10‰ to 7.67 0.14‰ (2σ)], inherited age spectra, as well F/Cl ratios compositions, suggest granites by partial melting ancient thickened lower continental crust Yangtze Craton. Magma evolution modelling based on Rb Rb/Nb similar decoupled assimilation-fractional crystallization process generation with different assimilation degrees. water contents parental magma evaluated using Ba, Sr F, Cl indicate in relatively water-rich environment Luanjiahe. This is consistent presence amphibole minor negative Eu anomalies granite, input can promote fractionation suppresses plagioclase crystallization. Considering sources distinct granites, oblique Paleo-Pacific subduction Jurassic, fluids were likely released ocean beneath stacked crust. Since earliest mafic dikes (OIB-type) are coeval we associated roll-back resulted an increasing distance slab Such tectonic transition compression Ma) initial extension (152 perhaps possibly marks beginning