黑龙江南蛤拉河子地区早侏罗世花岗岩演化及构造环境

黑龙江南蛤拉河子地区花岗岩分布广泛,岩性主要为石英闪长岩、黑云母花岗闪长岩、黑云母二长花岗岩。通过对花岗岩进行了锆石年龄分析测试和岩石地球化学的分析研究,结果表明石英闪长岩、黑云母花岗闪长岩、黑云母二长花岗岩形成于早侏罗世,随着SiO_2含量的增加,Fe_2O_3、FeO、MgO、Al_2O_3、MnO、CaO、TiO_2含量逐渐减少,K_2O含量逐渐增加,且向富钾方向演化;Rb、U、Th、K等逐渐富集,Nb、Ti、P逐渐亏损;轻稀土和重稀土总量逐渐逐渐增加,Eu从无异常或弱的负异常到强烈负异常。早侏罗世花岗岩为"I"型花岗岩,其与太平洋板框向欧亚板块俯冲有关。

LIAS GRANITE EVOLUTION AND THE STRUCTURAL ENVIRONMENT OF NANHALAHEZI REGION IN HEILONGJIANG PROVINCE

There are quartz diorite, biotite granodiorite and biotite adamellite in Nanhalahezi. The anlysis on U-Pb age testing and lithogeochemistry of zircon showed that the quartz diorite, biotite granodiorite and biotite adamellite were formed at Early Jurassic. The increase of SiO2 content result in the decline of Fe2O3,FeO,MgO,Al2O3, MnO, CaO, TiO2 ,and the increase of K2O.At the same time, Rb,U,Th and K elements are rich ,but the Nb,Ti,P elements are lose. The total quantity of light and heavy rare earth are gradually increase. The Eu elements are vary from no abnormalities to weak and strong negative anomaly. The formation of “I” granite were caused by pacific plate subducting to eurasian plate.