华北陆块北缘尚义地区下井-- 厂汉营韧性剪切带变形特征及年代学研究
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:

本文为中国地质调查局 (编号12120110200150009)、云南省科学技术奖- 杰出贡献奖(编号2017001)和云南省应用基础研究计划青年项目(编号2016DF031)联合资助的成果。


Deformation characteristics and geochronology of the Xiajing- Changhanying ductile shear zone in the Shangyi area, northern margin of North China block
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    华北陆块北缘晚古生代经历了多期构造事件,构造活动复杂多样,位于其中段的下井- 厂汉营韧性剪切带构造变形强烈,研究其变形特征以及形成时代,对进一步探讨华北陆块北缘晚古生代构造演化特别是古亚洲洋晚阶段洋壳俯冲的时间和机制有重要意义。鉴于此,对该韧性剪切带进行了运动学和几何学实测剖面、显微构造解析及锆石LA- ICP- MS U- Pb年代学等综合研究,以期限定韧性剪切带变形特征和时间。剪切带内原岩为一套闪长质- 花岗质岩浆岩,后期遭受走滑剪切作用形成花岗质糜棱岩和闪长花岗质糜棱岩以及构造深融作用析出同变形钾长花岗质糜棱岩脉,后期被未变形的角闪辉绿岩脉所侵位,从而划分出变形前期花岗质- 闪长花岗质糜棱岩、同变形期细脉状钾长花岗质糜棱岩和变形期后未变形角闪辉绿岩3个阶段。其中糜棱岩面理近E—W或SW—NE走向,倾向NW—N,倾角较陡,线理倾伏向为SW向,倾伏角较缓,带内发育拉伸线理、S- C组构、不对称褶皱、旋转残斑、多米诺碎斑等宏观和微观构造,指示剪切带性质为左行走滑剪切变形特征。采集变形前期、同变形期和变形后期岩石进行锆石LA- ICP- MS U- Pb年代学研究,获得3期锆石206Pb/238U谐和年龄为286. 7±4. 1 Ma、280. 0±5. 5 Ma和278. 8±0. 6 Ma,最终认为下井- 厂汉营韧性剪切带左行走滑变形的时代为~280 Ma,即早二叠世晚期。综合区域中亚造山带南缘构造- 岩浆时代、动力学背景及演化过程资料,认为下井- 厂汉营韧性剪切带形成于中亚造山带东南缘兴安俯冲- 增生造山带挤压闭合到索伦- 西拉木伦河一线造山后伸展构造转换调节作用。

    Abstract:

    The northern margin of North China block experienced multiple tectonic events in the late Paleozoic, with complex and diverse tectonic activities. The Xiajing- changhanying ductile shear zone located in the middle segment of the North China block underwent strong tectonic deformation. The study of the deformation characteristics and formation age of the ductile shear zone is of great significance to further explore the tectonic evolution of the northern margin of the North China block, especially the timing and mechanism of oceanic subduction crust in the late stage of Paleo- Asian Ocean. In view of this, the kinematic and geometric profiles, microstructural analysis and zircon LA- ICP- MS U- Pb geochronology of the ductile shear zone were carried out in order to define the deformation characteristics and time of the ductile shear zone. The protoliths in the shear zone are a set of dioritic- granitic magmatic rocks, which were formed by strike slip shearing in the later stage. The synmorphic potassium feldspar granitic mylonite veins were precipitated by the tectonic deep melting, and were emplaced by the undeformed hornblende diabase veins in the later stage. Thus, three stages i.e. an early stage of the deformation of granitic diorite- granitic mylonite, long with deformation fine vein potassium granitic mylonite, and post deformation undeformed hornblende diabase can be identified. Among them, mylonite foliation is close to E—W or SW—NE trend, inclining to NW—N, with steep dip angle, SW dip direction and gentle dip angle. Macro and micro structures such as tensile lineation, S- C fabric, asymmetric fold, rotary remnant and domino porphyroclastic structure are developed in the zone, indicating that the nature of the shear zone is characterized by left lateral strike slip shear deformation. Zircon LA- ICP- MS U- Pb geochronology of the early, syn- and post- deformation rocks was carried out. The zircon 206Pb / 238U concordant ages of 286.7±4.1 Ma, 280.0±5.5 Ma and 278.8±0.6 Ma were obtained. It is concluded that the age of left strike slip deformation in the Xiajing- Changhanying ductile shear zone is ~ 280 Ma, that is, the late Early Permian. Based on the data of tectonic magmatic age, dynamic background and evolution process in the southern margin of the Central Asian orogenic belt, it is considered that the Xiajing- Changhanying ductile shear zone was formed during the compression of the Xingan subduction accretionary orogenic belt on the southeastern margin of the Central Asian orogenic belt to the post orogenic extensional tectonic transformation along the Solun Xilamulun river line.

    参考文献
    相似文献
    引证文献
引用本文

李亚东,柳永清,江小均,李超,彭楠,严清高,王忠强,甘熙.2022.华北陆块北缘尚义地区下井-- 厂汉营韧性剪切带变形特征及年代学研究[J].地质学报,96(3):863-880.
Li Yadong, Liu Yongqing, Jiang Xiaojun, Li Chao, Peng Nan, Yan Qinggao, Wang Zhongqiang, Gan Xi.2022. Deformation characteristics and geochronology of the Xiajing- Changhanying ductile shear zone in the Shangyi area, northern margin of North China block[J]. Acta Geologica Sinica,96(3):863-880.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2020-07-14
  • 最后修改日期:2020-10-13
  • 录用日期:2021-01-08
  • 在线发布日期: 2021-02-22
  • 出版日期: