Geochronology and Petrogenesis of Granitoid Intrusions in the Feidong District, Southern Tan–Lu Fault Zone, China

The Feidong district is located in the southern segment of the Tan–Lu fault zone that separates the South China Block (NCB) from the North China Craton (NCC). We report zircon U-Pb geochronology and Hf isotope data, as well as whole-rock geochemistry for Xishanyi granodiorite and Jianshan granite in the Feidong district. Zircon U-Pb dating results show that the emplacement ages of the Xishanyi and Jianshan intrusions are 124 ± 3 Ma and 130 ± 1 Ma respectively, coeval with magmatic events linked to large-scale lithospheric thinning in eastern China. The whole-rock geochemistry of the Xishanyi and Jianshan intrusions demonstrate that they are peraluminous, high potassium calc-alkaline I-type granites with adakitic characteristics. Both intrusions underwent weak crustal assimilation during emplacement. The in situ zircon εHf(t) values of the Xishanyi granodiorites range from ?26.4 to ?21.8, with TDM2 model ages of 2552 to 2841 Ma. The in situ zircon εHf(t) values of the Jianshan granite are from ?27.5 to ?23.0 with TDM2 model ages of 2632 to 2904 Ma. The peak age of inherited zircon grains from the Xishanyi granodiorite and the Jianshan granite were ~2.07 Ga and ~1.94 Ga, respectively. After compared with the regional magmatism, we suggest that both the Xishanyi and Jianshan granitoid intrusions were derived from partial melting of the NCC lower crust.