小兴安岭东南部伊春中生代花岗岩的锆石U-Pb测年及其地质意义

LA.ICPMS zircon U-Pb age and the geological significance for Yichun Mesozoic granites in Southeast Lesser Khingan Range

本文首次报道了小兴安岭南部伊春地区的五三零、南岔三林场及寒月林场岩体高精度锆石LA-ICP-MS U-Pb年龄。三个岩体均形成于早侏罗世,侵位年龄分别为175±3 Ma,180±2 Ma和195±2 Ma。岩石学和地球化学特征显示,这些岩体为高硅富碱性的钙碱性系列的二长花岗岩.花岗闪长岩组合,形成于造山后的伸展构造环境中,其大地构造背景与早侏罗世佳木斯板块和松嫩.张广才岭板块碰撞拼合后伸展作用有关。

The Wulingsan Nanchasan and Hanyue Tree Farms granites in Southeast Lesser Khingan Range was fi rstly dated by high precision LA.ICPMS zircon U-Pb dating technique.These three intrusive bodies all were born in Jurassic have the Zircon U-Pb ages of 175±3Ma 180±2Ma and 195±2Ma separately.A study on petrology and geochemistry show that these granites consisted of Monzonite granite and granodiorite,and have some characteristics of high silicon,rich in alkali and calc alkaline series.The author thinks these granites generated in the background of spreading tectonics,and are likely to be related to the colliding between Kiamusze plate and Songnen.Zhangguangcai plate in Early Jurassic and regional extension after this.