地学前缘 ›› 2019, Vol. 26 ›› Issue (2): 16-41.DOI: 10.13745/j.esf.sf.2019.3.1

• 陆内构造与变形机制 • 上一篇    下一篇

扬子地块西南缘瓮安穹隆不整合面特征、年代限定及大地构造意义

宋志冬,颜丹平,邱亮,张翼西   

  1. 1. 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2. 中国地质大学 地质过程与矿产资源国家重点实验室, 北京 100083
  • 收稿日期:2018-10-25 修回日期:2018-12-26 出版日期:2019-03-30 发布日期:2019-03-30
  • 通讯作者: 颜丹平(1963—),男,博士,教授,博士生导师,构造地质学专业。
  • 作者简介:宋志冬(1986—),女,博士研究生,构造地质学专业。E-mail:songzhidong1234@126.com
  • 基金资助:
    国家重点基础研究发展计划“973”项目(2014CB440903);国家自然科学基金项目(41372212,41672216)

Unconformity characteristics, age constraint and tectonic significance of the Weng'an Dome in southwestern Yangtze Block

SONG Zhidong,YAN Danping,QIU Liang,ZHANG Yixi   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
  • Received:2018-10-25 Revised:2018-12-26 Online:2019-03-30 Published:2019-03-30
  • Supported by:
     

摘要: 瓮安穹隆位于近南北向的鄂渝湘黔穹隆群构造带与东西向黔中隆起的过渡区域,本质上为一构造叠加穹隆。瓮安穹隆及周缘发育并完好地保留了加里东期、印支期和燕山期不整合面。这些对应于关键构造事件的不整合面的发育特征和年代限定是进行区域和大地构造重建的重要手段。研究结果表明:(1)古生代以来瓮安穹隆及邻区构造格局出现3次重大变动,先后经历了加里东期、印支期、燕山期等3个关键演化阶段,是前震旦陆壳基底上的叠加穹隆。早古生代以来,瓮安穹隆及邻区主要发育中志留统顶面(S2/AnS2)、中三叠统顶面(T2/AnT2)、中侏罗统顶面(J2/AnJ2)不整合,分别与加里东期、印支期和燕山期构造运动有关。(2)根据碎屑锆石年龄分布统计结果,瓮安地区及邻区加里东运动的发生时间为426~415 Ma,印支运动的发生时间为246~233 Ma,燕山运动发生的时间为168~150 Ma。对瓮安穹隆出现的不整合进行构造及年代学分析,从而进一步探讨穹隆的构造演化,将有助于对穹隆构造的深入研究。

 

关键词: 扬子地块, 瓮安穹隆, 不整合面, 碎屑锆石分析

Abstract: The Weng'an Dome is located in the transitional region between the Hubei-Chongqing-Hunan-Guizhou dome group in near N-S direction and the Qianzhong Uplift in the E-W direction. Our research suggests that the Wengan Dome is essentially a superimposed tectonic dome. Caledonian, Indosinian and Yanshanian unconformities are developed and well retained in the Wengan Dome and its surrounding area. Unconformity characteristics corresponding to key tectonic events and age constraint are important factors in reconstructing regional geology and tectonics. Our results can be summarized as follows: (1) The Wengan Dome experienced three major deformations during the Paleozoic and Mesozoic. It is a superimposed tectonic dome with cratonic basement. The S2/AnS2, T2/AnT2 and J2/AnJ2 unconformities are distinguishable within the Weng'an Dome and its surrounding area, and they correspond to the Caledonian, Indosinian and Yanshanian tectonic movements in the Yangtze Block, respectively. And (2) The ages of unconformities, constrained by using detrital zircon U-Pb method, demonstrate that the Caledonian, Indosinian and Yanshanian tectonic events occurred during 426415, 246233 and 168150 Ma, respectively. Through structural and chronological analyses of unconformities, we also explored the tectonic evolution of the dome, which shall contribute to the in-depth study of the dome structure.

Key words: Yangtze Block, Weng'an Dome, unconformity, detrital zircon analysis

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