LA-ICP-MS zircon U-Pb geochronology of the Huyanshan alkaline intrusive complex in the Lüliang Mountain of North China Craton and its geological significance

In order to constrain the age of alkaline magmatism, the authors determined U-Pb zircon ages by the high accuracy LAICP-MS method for the early and late stage of Huyanshan alkaline intursive complex. Zircons from monzonite yielded a weighted mean ²⁰⁶Pb/²³⁸U age of 127±1Ma, indicating that the monzonite occurred at the early stage of the Early Cretaceous, corresponding to the peak time of alkaline magmatism in central North China Craton. Zircons from syenite have a weighted mean ²⁰⁶Pb/²³⁸U age of 114±4 Ma, suggesting that the syenite was formed at the late stage of the Early Cretaceous, representing the last alkaline magma activity in central North China Craton. The time of alkaline magmatism was consistent with the magmatism in east of North China Craton, which was the peak period of lithospheric thinning of North China Craton. In addition, the inherited zircons have ages of 2.5~ 2.4Ga and 2.2~2.1Ga, respectively, corresponding to the cratonization stage of North China Craton and the intracontinental extension-rifting event in 2.3~2.0Ga. The age of ~1.8Ga for inherited zircons resulted from intracontinental rifting and mass magmatism in the North China Craton. The ages of 232~220Ma were given by inherited zircons, representing magmatic-tectothermal event of North China Craton in Late Triassic.