College of Earth Sicences, Jilin University, Changchun 130061, China

LA-ICP-MS zircon U-Pb dating and petrochemical analysis were used to study the formation age, geochemical characteristics and diagenetic environment of Shangyingbei pluton and Maoershan pluton from southern Zhangguangcai Range. Shangyingbei pluton consists of mid-coarse-grained moyite and Maoershan pluton consists of mid-fine-grained biotite moyite. The weighted average age of the plutons are 178.9±2.7 Ma for Shangyingbei pluton and 183.7±2.4 Ma for Maoershan pluton, which define them both as Early Jurassic intrusive rock. Both plutons have higher content of SiO₂ and K₂O, and lower content of TiO₂, MgO, CaO, and higher TFeO/MgO ratio. In Shangyingbei pluton the Aluminum index A/CNK=0.98~1.08 and the Rittmann Index σ=1.51~2.66, whereas in Maoershan pluton the A/CNK=1.00~1.01, σ=2.12~2.36. The rare earth element distribution model of Shangyingbei pluton is in seagull form, indicating an inconspicuous light-heavy REE fractionation, while Maoershan pluton has a rightwards REE element distribution model, and light REE is more enriched than heavy REE. Both plutons are enriched in Rb,K, and depleted in Ba,Nb,Ta,Sr,Ti,P,Ho,Er,U,Eu etc. Geochemical analysis indicates both plutons are A₂-type post orogenic granite, emplaced in extensional environment of the post orogenic belt in the Xing-Meng orogenic belt.