Zircon U- Pb age and geological significance of quartz monzonite from Qingjianpo, Shanxi Province

In this paper, based on the study of Qingjianpo quartz monzonite of zircon U-Pb isotope age, and combine with the major element data and rare earth elementdata, the authors investigated its geological significance. The LA-ICP-MS zircon U-Pb isotopic age of quartz monzonite is 241.1±1.7Ma, revealing that it is a product of the Early-Middle Triassic magmatism. The rock is enriched in K, Na, Si, Al and depleted in Mg, Ca, Ti, belonging to high calc alkaline shoshonite series and peraluminous granitoid. The rock exhibits the enrichment of LREE relative to HREE, and Eu shows weak negative anomaly. The genetic type of Qingjianpo quartz monzonite is I-type granite. with some features of S-type granites. Qingjianpo quartz monzonite characteristics indicate that the rock was formed from partial melting of the mid-lower crust, with the addition of mantle material. Qingjianpo quartz monzonite is a part of the alkaline magmatic belt of Middle Triassic on the northern margin of North China Craton, and it was formed in the extensional tectonic environment of late orogenic-post-orogenic activity.