地学前缘 ›› 2022, Vol. 29 ›› Issue (2): 416-430.DOI: 10.13745/j.esf.sf.2021.10.50

所属专题: 印度-欧亚大陆碰撞及其远程效应

• “印度-欧亚大陆碰撞及其远程效应”专栏之四 • 上一篇    

白垩纪羌塘地体西南缘的陆-陆碰撞:来自班怒带西段的花岗岩约束

付顺1,3(), 赵应权2,*(), 王进军4, 余瑜2, 朱迎堂5, 傅星喆6   

  1. 1.成都理工大学 数学地质四川省重点实验室, 四川 成都 610059
    2.成都理工大学 油气藏地质及开发工程国家重点实验室, 四川 成都 610059
    3.成都理工大学 数理学院, 四川 成都 610059
    4.四川省核工业地质局 二八三大队, 四川 达州 635099
    5.海南省地质局, 海南 海口 570206
    6.西南交通大学 希望学院, 四川 成都 650059
  • 收稿日期:2021-10-25 修回日期:2022-02-10 出版日期:2022-03-25 发布日期:2022-03-31
  • 通信作者: 赵应权
  • 作者简介:付 顺(1971—),男,副教授,主要从事第四纪地质及地质遗迹调查评价研究。E-mail: fs@cdut.edu.cn
  • 基金资助:
    国家科技基础资源调查专项“第二次青藏高原综合科学考察研究”项目(2019QZKK0803)

Continent-continent collision at the southwestern margin of the Cretaceous Qiangtang terrane: Constraints from granite in the western Bangong-Nujiang Suture Zone

FU Shun1,3(), ZHAO Yingquan2,*(), WANG Jinjun4, YU Yu2, ZHU Yingtang5, FU Xingzhe6   

  1. 1. Sichuan Provincial Key Laboratory of Mathematical Geology, Chengdu University of Technology, Chengdu 610059, China
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China
    3. College of Mathematics and Physics, Chengdu University of Technology, Chengdu 610059, China
    4. No.283 Team, Sichuan Geological Bureau, Dazhou 635099, China
    5. Hainan Geological Bureau, Haikou 570206, China
    6. Hope College, Southwest Jiaotong University, Chengdu 610400, China
  • Received:2021-10-25 Revised:2022-02-10 Online:2022-03-25 Published:2022-03-31
  • Contact: ZHAO Yingquan

摘要:

羌塘地体西南缘布木错—雄巴日—羌多—赛登地区分布着大量呈岩株或岩枝状的中酸性-基性侵入岩,其岩石地球化学特点是低SiO2(67.99%~73.32%)、高Al2O3(12.82%~15.02%),属于过铝质花岗岩,里特曼指数(2.09~2.63)σ<3.3,属钙碱性花岗岩类;稀土元素显示为轻稀土较强富集和重稀土强亏损的特征,岩浆结晶分异程度较高。岩石地球化学特征和稀有元素特征图解指示花岗岩构造环境有一定的差异性,以I型为主,其形成及侵位应与古特提斯洋的闭合、新特提斯洋的扩张有关,属同碰撞型造山花岗岩。通过对该区多个花岗岩体锆石LA-ICPMS 测定,测得其形成年代为116~107 Ma,与早白垩世晚期羌塘地体南缘的陆-陆碰撞作用时间相吻合。

关键词: 白垩纪, 羌塘地体, 班怒带, 陆-陆碰撞, 花岗岩

Abstract:

A large number of moderately felsic to basic intrusive rocks in the forms of rock strains or rock branches are distributed in the southwestern margin of the Qiangtang terrane. These intrusive rocks are characterized by petrographic analysis as peraluminous granite with low SiO2 (67.99%-73.32%) and high Al2O3 (12.82%-15.02%) contents, and defined as calc alkaline based on the Ritmann serial indices of 2.09-2.63 (σ<3.3). They show strong enrichment of light rare earth elements (REE) and strong depletion of heavy REE, with a high degree of magma crystallographic differentiation. The geochemical characteristics of the rocks and REE in granite indicate its tectonic environment is mainly type I, with some variability, and its formation and intrusion should be related to the closure of the ancient Tethys Ocean and the expansion of the new Tethys Ocean, which suggests an intracontinental collisional orogenic granite origin. The zircon laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS) dating of several granite masses in this area yielded a formation age of 107-116 Ma, which is consistent with the time of continent-continent collision at the southern margin of the Qiangtang terrane in the late Early Cretaceous.

Key words: Cretaceous, Qiangtang terrane, Bangong-Nujiang suture zone, continent-continent collision, granite

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