SHRIMP zircon U-Pb ages and Hf isotopic compositions of Zhangshiying intrusive complex in the southern margin of the North China Craton and their geological implications

Zhangshiying intrusive complex (ZIC), consisting of K-feldspar granite, granite porphyry and quartz porphyry, is located in the southern margin of the North China Craton. The mafic enclaves are merely in K-feldspar granite and have textures indicating magma mixing. We obtained their SHRIMP zircon U-Pb ages of 107.3 +/- 2.4Ma, 106.7 +/- 2.5Ma and 101 +/- 3Ma for K-feldspar granite, granite porphyry and quartz porphyry, respectively. According to zircon Hf isotope analyses, their epsilon(Hf)(t) values are -15.96 similar to -20.80, -18.97 similar to -22.18 and -23.41 similar to -27.95 and their corresponding Hf two-stage model ages(t(DM2)) are 1880 similar to 2018 Ma, 1925 similar to 2080Ma and 2144 similar to 2330 Ma. One exception is the zircon inherited Arehean information with (207)Pb/(26)Pb age of 2.6 Ga, -0.71 of epsilon(Hf)(t) and 3.0 Ga of t(DM2). These data suggest that the source of ZIC is mainly either juvenile crust formed at 1.9 similar to 2.3Ga or an enriched mantle source with the contribution of Archean continental crust. On integration of regional research results, we suggest that ZIC could form at a regional lithospheric extensional setting which is confined to the existing NE-SW or NW-SE fault zones and is triggered by the drifting direction of the Pacific plate changing to southwest ward.