李生伟,韦梅华,黄庭,刘强

• 1:青海大学地质工程系
• 2:山西省第一水文地质工程地质队
• 3:中国地质大学(武汉)地球科学学院

摘要(Abstract)：

仲巴地块是藏南雅鲁藏布江缝合带西段的重要构造单元，对于研究冈瓦纳大陆北缘微地块的构造属性与古地理重建具有重要意义。目前，对于该地块内部是否存在陆块基底尚未有统一认识。通过野外观测、岩石地球化学和锆石U-Pb年代学分析，本研究在仲巴地块中段公珠错南地区识别出一套黑云斜长片麻岩，其w(SiO_2)为64.09%～69.87%,w(Al_2O_3)为12.18%～18.30%,w(TiO_2)为0.55%～0.79%,w(K_2O)为2.53%～3.54%,LREE相对富集，轻重稀土分馏明显，推测其原岩以长石砂岩为主，形成于活动大陆边缘环境。锆石U-Pb年代学分析结果显示，其继承核年龄峰值为2 500,1 600,950 Ma,最年轻的谐和年龄为630 Ma。此外，还获得变质锆石的加权平均年龄为550 Ma。根据上述结果，研究认为公珠错片麻岩形成于新元古代晚期(630～550 Ma),其变形-变质程度较高，能够代表仲巴地块的陆块基底，并进一步证明仲巴地块是印度大陆北缘的组成部分。由此，本次研究为明确雅鲁藏布江缝合带西段仲巴地块的陆块基底特征及构造属性提供了直接的地质证据。

关键词(KeyWords)： 锆石年代学;雅鲁藏布缝合带;仲巴地块;公珠错;片麻岩

Abstract:

Keywords:

基金项目(Foundation): 中国地质调查局项目(1212011221066)

作者(Author): 李生伟,韦梅华,黄庭,刘强

DOI: 10.19509/j.cnki.dzkq.2021.0085

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