西藏卡贡地区晚寒武世错多勤石英闪长岩LA-ICP-MS锆石U-Pb年龄及其构造意义  

LA-ICP-MS zircon U-Pb age of Late Cambrian Cuoduo-qin quartz diorite in Kargangarea and its significance

作　　者：樊炳良 王新然 白涛[3] 余佳树 冯德新 徐长昊[3] FAN Bingliang;WANG Xinran;BAI Tao;YU Jiashu;FENG Dexin;XU Changhao(Geothermal Geological Survey Party,Tibet Bureau of Geology and Mineral Exploration and Development,Lhasa 850000,Tibet,China;Geological Exploration in Statute of Henan,Zhengzhou 451464,Henan,China;College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,Sichuan,China)

机构地区：[1]西藏自治区地质矿产勘查开发局地热地质大队,西藏拉萨850000 [2]河南省地质矿产勘查开发局第三地质勘查院,河南郑州451464 [3]成都理工大学地球科学学院,四川成都610059

出　　处：《地质通报》2020年第4期471-479,共9页Geological Bulletin of China

基　　金：中国地质调查局项目《西藏卡贡地区1:5万四幅区域地质调查》(编号:DD20160016-21)。

摘　　要：对卡贡地区错多勤石英闪长岩进行了LA-ICP-MS锆石U-Pb测年工作,获得该岩体的206Pb/238U年龄加权平均值为495.9±3.2 Ma(MSWD=1.8,n=24),属于晚寒武世的产物。岩石地球化学特征表明,岩石具有低钾富钠(Na2O/K2O=4.16~5.47)、低碱(K2O+Na2O=6.41%~6.67%)、低铝(Al2O3=14.64%~14.98%,A/CNK≈0.9)的特征,属于低钾钙碱性准铝质I型花岗岩。岩石稀土元素总体表现为轻稀土元素相对富集的左陡右缓的右倾型,相对亏损Nb、Sr、P、Ti等高场强元素,富集Rb、Th、U等大离子亲石元素,具有岛弧型花岗岩的特征。结合区域地质资料分析,该岩体与区内原特提斯洋的俯冲存在成因联系,错多勤石英闪长岩的发现有助于进一步探索原特提斯洋演化过程。LA-ICP-MS zircon U-Pb age test was carried out on the Cuoduo-qin quartz diorite in Kargang area, and the result shows that the 206Pb/238U age weighted average value of the rock mass is 495.9±3.2 Ma (MSWD=1.8 n=24), suggesting a product of Late Cambrian.The geochemical characteristics of the rocks show that the rocks have the characteristics of low potassium rich sodium (Na2O/K2O=4.16~5.47), low alkali (K2O+Na2O=6.41%~6.67%), and low aluminum (Al2O3=14.64%~14.98% A/CNK≈0.9), implying low potassium calcium alkaline quasi-aluminum type I granite.The overall performance of the rare earth elements is the right-inclined type of the relative enrichment exhibiting steep shape on the left and smooth shape on the right for the light rare earth elements, the relative loss of Nb, Sr, P, Ti and other high field strength elements, and enrichment of Rb, Th, U and other large ionic pro-stone elements, with the characteristics of island arc granite.Combined with the analysis of regional geological data, the authors hold that there is a genetic connection between the rock mass and the subduction of the original Tethys Ocean in this area, and the discovery of the Cuoduo-qin quartz diorite is helpful to further exploration of the original Tethys Ocean evolution process.

关 键 词：错多勤石英闪长岩 岩石地球化学特征 LA-ICP-MS锆石U-PB测年 岩石成因 

分 类 号：P534.41[天文地球—古生物学与地层学] P597.3[天文地球—地质学]