Abstract

Info

Title:: LA-ICP-MS Zircon U-Pb Dating, Geochemical Characteristics and Geological Significance of Daxing Pluton in Liaodong Area

Author(s):: CUI Wei-long; LIU Zheng-hong; DU Yang; WANG Shi-jie; WAN Le; College of Earth Sciences, Jilin University, Changchun 130061, Jilin, China

Keywords:: I-ype granite; zircon U-Pb age; petrogeochemistry; petrogenesis; Early Cretaceous; local extension; Liaoning

Abstract:: The petrology, geochemistry and zircon U-Pb ages of Daxing pluton in Liaodong area were studied, and the formation ages of granites were measured, and the petrogenesis and tectonic significance of granites were discussed. The results show that the zircons of Daxing granite have the characteristics of oscillatory growth zonation of typical magmatic origin and high ratios of the contents of Th and U (0.54-1.27), indicating a magmatic origin for the zircons; LA-ICP-MS zircon U-Pb age of Daxing pluton is (120±1)Ma, showing that the granites are formed in the late Early Cretaceous; geochemical characteristics suggest that Daxing granite is peraluminous high-K calc alkaline, and is featured by high SiO₂and alkaline, and low CaO, Fe₂O₃, MgO and P₂O₅, and high rare earth element (REE); the chondrite-normalized REE pattern with right oblique and V-shaped feature is characterized by enrichment of light rare earth element(LREE) relative to heavy rare earth element (HREE) and distinct negative Eu anomalies, and Rb, Th, U, Ta, Hf and Gd are enriched, and Ba, Sr, P and Ti are depleted; zircon saturation temperatures (724 ℃-816 ℃) of granite melt are significantly lower than Cretaceous A-type granites (868 ℃-928 ℃). These characteristics indicate that the granites in Daxing area of Liaodong should belong to highly fractionated I-type granites, which are formed in local extensional tectonic surrounding.