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    邹光富, 林仕良, 李再会, 丛峰, 谢韬, 唐文清. 滇西潞西邦木二长花岗岩SHRIMP锆石U-Pb年龄及其构造意义[J]. 中国地质, 2011, 38(1): 77-85.
    引用本文: 邹光富, 林仕良, 李再会, 丛峰, 谢韬, 唐文清. 滇西潞西邦木二长花岗岩SHRIMP锆石U-Pb年龄及其构造意义[J]. 中国地质, 2011, 38(1): 77-85.
    ZOU Guang-fu, LIN Shi-liang, LI Zai-hui, CONG Feng, XIE Tao, TANG Wen-qing. SHRIMP Zircon U-Pb dating of Bangmu admellite in Luxi, western Yunnan, and its tectonic implications[J]. GEOLOGY IN CHINA, 2011, 38(1): 77-85.
    Citation: ZOU Guang-fu, LIN Shi-liang, LI Zai-hui, CONG Feng, XIE Tao, TANG Wen-qing. SHRIMP Zircon U-Pb dating of Bangmu admellite in Luxi, western Yunnan, and its tectonic implications[J]. GEOLOGY IN CHINA, 2011, 38(1): 77-85.

    滇西潞西邦木二长花岗岩SHRIMP锆石U-Pb年龄及其构造意义

    SHRIMP Zircon U-Pb dating of Bangmu admellite in Luxi, western Yunnan, and its tectonic implications

    • 摘要: 提要:为了查明出露于云南省西部潞西市邦木二长花岗岩体的时代和形成的构造背景,对其进行了锆石SHRIMP定年研究。结果显示该花岗岩的锆石具有清晰的生长振荡环带,其Th/U比值为0.13~1.00,属于典型的岩浆成因锆石。邦木二长花岗岩中锆石的8个测点206Pb/238U 年龄加权平均值为(120.5 ± 1.7) Ma(n=8,MSWD =1.6)(95%置信度),代表了岩体的结晶年龄,表明该花岗岩体的形成时代为早白垩世。岩石地球化学研究表明,邦木二长花岗岩为过铝质钙碱性I型花岗岩,形成于早白垩世岛弧构造环境,具有岛弧花岗岩的特征,属于燕山中期侵入的花岗岩。在中—晚侏罗世,左贡—保山微板块沿班公湖—怒江—泸水—瑞丽板块缝合带由北东向南西方向与波密—腾冲微板块发生洋壳俯冲,导致班公湖—怒江—泸水—瑞丽洋关闭。左贡—保山板块俯冲插入到波密—腾冲板块之下。晚侏罗世末—早白垩世初,随着板块俯冲碰撞造山作用的进行,形成波密—腾冲岛弧。不同板块之间的碰撞拼合导致大规模的中酸性岩浆形成、侵入活动。邦木二长花岗岩就是这期构造岩浆活动的产物。邦木二长花岗岩体形成时代的厘定,为进一步探讨腾冲地块中生代构造演化提供了新证据。

       

      Abstract: Abstract:SHRIMP zircon U-Pb dating of the Bangmu admellite in Luxi of western Yunnan Province was carried out in order to determine the age and discuss the tectonic environment of the granite. The results show that the zircons from the granite have clear oscillatory zones,their Th/U ratio is between 0.13 and 1.00, and their weighted average 206Pb/238U age is (120.5 ± 1.7) Ma(n=15,MSWD = 1.6), suggesting that the crystallization age of the Bangmu admellite is Early Cenozoic. Geochemistry of the granite shows that it is of the Al-supersaturated type and belongs to typical strongly peraluminous I-granite. The Rb-(Yb+Ta) and Rb-(Nb+Yb) diagrams of the granite indicate that the granite was formed in a valconi arc granite (VAG) setting. With the features of the valconi arc magmatic activity, the granite is the product of partially melted crust in a geological condition of crustal thickening resulting from the subduction and collision between the Zogang-Baoshan continental massif and Bomi-Tengchong massif along Bangong Lake-Nujiang-Linshui-Ruili suture zone from northeast to southwest during the Late Jurassic and Early Cretaceous period. The granite was formed in the valconi arc period and the compressional environment. The determination of the Bangmu admellite’s crystallization provides new evidence for the Paleozoic tectonic evolution of the Tengchong massif.

       

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