巴颜喀拉山东段花岗岩锆石SHRIMP定年及其地球化学特征

巴颜喀拉山东段花岗岩直接侵入到已发生褶皱的三叠纪地层中,并被侏罗系年宝组不整合覆盖,其锆石SHRIMP U-Pb年龄为218～197 Ma.岩石类型主要为花岗闪长岩、二长花岗岩和正长花岗岩,岩石具似斑状结构或斑状结构,富铝高钾,富黑云母,含石榴子石和电气石等富铝矿物及暗色微细粒闪长质包体的发育为特征,铝饱和指数A/CNK=1.00～1.22,属巴尔巴林划分的CPG型花岗岩类.形成于巴颜喀拉山造山带陆内碰撞造山阶段的晚期.

Zircon SHRIMP Dating and Geochemical Characteristics of Granites in the Eastern Part of the Bayan Har Mountains

In the eastern part of the Bayan Har Mountains, granites with the SHRIMP U-Pb age of 218197 Ma directly intruded folded Triassic strata and are unconformably covered by Jurassic Nianbao Formation. These granites, composed of granodiorite, adamellite and syenogranite, have porphyritoid or porphyritic texture and abundant aluminum and potassium. In addition, they are characterized by lots of biotites, some aluminum-rich minerals such as garnets and tourmalines, and some gray fine dioritic inclusions. With A/CNK 1.001.22, they should belong to CPG-type granite in Barbarin's classification. They were formed at the late stage of Bayan Har intracontinental orogenic activity.