Geochemical characteristics and petrogenesis of Early Cretaceous monzonitic granite in theMandu area, southern Da Hinggan Mountains

The monzonitic granite pluton is located in the Xing'an block, southern Da Hinggan Mountains. The rocks are composed of fine-grained porphyry monzonitic granite and fine-medium-grained monzonitic granite. The zircon U-Pb ages are 141.2±1.6 Ma and 134.0±1.9 Ma, indicating that they are the product of magmatic activity in the Early Cretaceous. Their geochemical characteristics suggest that they are highly differentiated I-type granites of high potassium calc-alkaline series. They are rich in large ion lithophile elements, such as Rb, Th, K and light rare earth elements (LREE), and strongly depleted in Ba, Sr, P and Ti elements. These features are similar to geochemical characteristics of crustal granite.They were formed in a post-collision extensional environment and serve as a magmatic record of the subduction of the Paleo-Pacific Plate.