滇西龙陵地区花岗岩LA-ICP-MSU-Pb定年及其地质意义  

LA-ICP-MS Zircon U-Pb Dating and Its Geological Implication for the Longling Granite in West Yunnan

作　　者：黄柏鑫[1] 白宪洲[1] 熊昌利[1] 罗改[1] 杨学俊[1] 贾小川[1] HUANG Bai-xin;BAI Xian-zhou;XIONG Chang-li;LUO Gai;YANG Xue-jun;JIA Xiao-chuan(Sichuan Institute of Geological Survey,Chengdu610081)

机构地区：[1]四川省地质调查院,成都610081

出　　处：《四川地质学报》2020年第3期371-374,共4页Acta Geologica Sichuan

基　　金：云南1∶5万清河街、镇安街、龙陵、龙新幅区域地质调查项目(编号:1212010784006)。

摘　　要：在详细区域地质调查的基础上,对滇西龙陵地区花岗质糜棱岩样品中的锆石进行了阴极发光图像、微区原位LA-ICP-MS微量元素分析和U-Pb定年。结果表明,梁河地区钾长花岗岩锆石显示振荡环带的内部结构,指示其岩浆成因。样品的锆石206Pb/238U加权平均年龄为(504.1±2.9)Ma,属中寒武世花岗岩。结合区域地质特征,龙陵地区在寒武纪存在岩浆作用,说明怒江缝合带以西的变质基底岩石经历过泛非造山运动,为青藏高原南部的构造演化提供了新资料。CL imaging,LA-ICP-MS U-Pb dating and trace element analysis are carried out for the zircon from granitic mylonite in the Longling region,west Yunnan.The zircon displays oscillatory zoning which suggests a magmatic origin and yields.The zircon from the granitic mylonite yields weighted average 206Pb/238U ages of 504.1±2.9 Ma which shows that the granite was emplaced in Middle Cambrian.Combined with regional geology,magmatism took place in the Longling region during the Middle Cambrian.The dating results show that the metamorphic basement to the west of the Nujiang suture zone experienced Pan-African orogeny.These provide fresh evidences for the tectonic evolution on the eastern margin of the Qinghai-Tibet Plateau.

关 键 词：滇西 龙陵 花岗岩 锆石U-PB年龄 

分 类 号：P597.3[天文地球—地球化学]