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 εHf(t) values are -15.96 - -20.80, - 18.97 - -22. 18 and -23. 41 - -27.95 and their corresponding Hf two-stage model ages (tDM2) are 1880-2018 Ma, 1925-2080Ma and 2144 - 2330 Ma One exception is the zircon inherited Archean information with 207Pb/206Pb age of 2.6 Ga, -0. 71 of εHf(t) and 3.0 Ga of tDM2. These data suggest that the source of ZIC is mainly either juvenile crust formed at 1.9 - 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