西藏门巴地区德宗花岗质片麻岩SHRIMP锆石U-Pb年龄及地质意义  

Zircon SHRIMP U-Pb Dating of Dezong Granitoid Gneisses and its Geological Implications in Menba Area, Tibet

作　　者：杨德明[1] 和钟铧[1] 郑常青[1] 王天武[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061

出　　处：《吉林大学学报（地球科学版）》2004年第B10期12-14,22,共4页Journal of Jilin University：Earth Science Edition

基　　金：国土资源部地质调查项目(H46002002)

摘　　要：德宗花岗质片麻岩体侵位于蒙拉组地层之中。阴极发光分析表明,样品的锆石具岩浆成因特点,离子探针(SHRIMP)U-Pb同位素年龄为(209±6.9)Ma,时代为晚三叠世。同时,对该样品中的黑云母进行40Ar-39Ar测年,其结果为(105.2±1.7)Ma。这些精确的年龄数据不仅进一步厘定了冈底斯地区的确存在晚印支期岩浆活动,也为该区蒙拉组变质变形的确定提供了科学依据。Dezong granitoid gneisses intruded into Mengla Formation. The CL images of zircon from Dezong granitoid gneisses reveal that zircons come from magma. High-resolution zircon SHRIMP U-Pb ages of (209±6.9) Ma (The late Triassic) indicate that Indosinian magmatic activity occurred in the Gangdisi area. In addition, the 40 Ar- 39 Ar dating of the biotite from the same sample is (105.2±1.7) Ma, which show the metamorphic age of Dezong granitoid gneisses and provide scientific basis for the timing of the metamorphism and deformation of Mengla Formation.

关 键 词：花岗质片麻岩 U—Pb年龄 蒙拉组 西藏门巴 

分 类 号：P534.51[天文地球—古生物学与地层学] P588.12[天文地球—地质学]