早三叠世北澜沧江结合带碰撞作用:类乌齐花岗质片麻岩年代学、地球化学及Hf同位素证据

被引：70

作者：

王保弟 ^{[1
]}

王立全 ^{[1
]}

强巴扎西 ^{[2
]}

曾庆高 ^{[2
]}

张万平 ^{[1
]}

王冬兵 ^{[1
]}

程万华 ^{[1
]}

机构：

[1] 成都地质矿产研究所

[2] 西藏地勘局区域地质调查大队

来源：

岩石学报 | 2011年 / 27卷 / 09期

关键词：

花岗质片麻岩; 碰撞型花岗岩; 锆石U-Pb年龄; 澜沧江结合带; 类乌齐; 西藏;

D O I：

暂无

中图分类号：

P588.121 [];

学科分类号：

摘要：

西藏东部类乌齐一带吉塘岩群中新识别出一套花岗质片麻岩,其Cameca锆石U-Pb年龄为246.3±0.8Ma,表明该变质花岗岩形成于早三叠世。该套变质侵入体具高SiO2(68.21%～74.82%)、富K2O(K2O/Na2O>1)和低P2O5(<0.26%)特征,铝饱和指数(ACNK)为1.01～1.19,属准铝质到过铝质岩石;富集Rb、Th和U,亏损Ba、Nb、Ta、Sr、P和Eu等;并具不均一的锆石εHf(t)值(-1.3～+3.7)和古老的锆石Hf同位素地壳模式年龄(1.0～1.4Ga),具有碰撞型花岗岩的地球化学特征。类乌齐变质侵入体很可能形成于澜沧江结合带所代表的洋盆闭合后碰撞的地球动力学背景,可能是幔源岩浆诱发古老地壳物质重熔并与之混合形成母岩浆,再经历高程度分离结晶作用而形成,为北澜沧江结合带碰撞造山过程的产物,暗示澜沧江结合带在早三叠世存在岩浆增生事件,藏东类乌齐地区在246Ma之前己进入陆-陆碰撞时期。

引用

页码：2752 / 2762

页数：11

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