Genesis of High Ba-Sr Yashan Intrusion from the Jiaodong Peninsula, Eastern China: Implications for the Destruction of the North China Craton

The origin of the Mesozoic high Ba-Sr (HBS) granitic magmatism in the Jiaodong Peninsula remains controversial in petrogenesis models and geodynamic settings. Here, we report zircon U-Pb age, trace element and oxygen isotope compositions, and whole-rock major-trace element and Sr-Nd isotope compositions of the HBS Yashan granodiorite. The zircon U-Pb age of similar to 118 Ma denotes that the Yashan granodiorite belongs to the Weideshan-stage magmatic activity, which is consistent with the age of Mo mineralization in the Yashan intrusion. The low Sr/Y (48.8-115) and high (La/Yb)(N) (23.8-50.4) ratios of the Yashan granodiorite are analogous to adakitic features derived from the lower-crust. This is also supported by the whole-rock initial Sr-87/Sr-86 ratios (0.709 6-0.710 3) and zircon delta O-8 values (6.79 parts per thousand-8.03 parts per thousand). Contemporaneous mantle-derived mafic microgranular enclaves indicate the involvement of the metasomatized lithospheric mantle. The high magma oxygen fugacity of the Yashan intrusion as indicated by high zircon Ce4+/Ce3+ values suggests the involvement of plate subduction. The obviously lower Dy/Yb, La/Yb and Sr/Y ratios of magmatic rocks in the Weideshan-stage than those in the early-stage imply lithospheric thinning of the eastern North China Craton. We propose that the Yashan HBS granodiorite was formed by crust-mantle interactions during slab rollback.