欢迎访问现代地质!

现代地质 ›› 2021, Vol. 35 ›› Issue (05): 1178-1193.DOI: 10.19657/j.geoscience.1000-8527.2020.096

• 岩石学 • 上一篇    下一篇

青藏高原东北缘祁连山三叠系砂岩碎屑锆石U-Pb定年及其物源分析

吴龙1(), 柳长峰2(), 刘文灿3, 张宏远3   

  1. 1.湖北省地质调查院,湖北 武汉 430034
    2.中国地质大学(北京) 海洋学院,北京 100083
    3.中国地质大学(北京) 地球科学与资源学院,北京 100083
  • 收稿日期:2020-06-30 修回日期:2021-08-30 出版日期:2021-10-10 发布日期:2021-11-04
  • 通讯作者: 柳长峰
  • 作者简介:柳长峰,男,副研究员,1982年出生,古生物学与地层学专业,主要从事区域地质研究。Email: liuchangfeng@cugb.edu.cn
    吴 龙,男,硕士研究生,1988年出生,构造地质学专业,主要从事构造地质、区域地质调查工作。Email: 609061644@qq.com
  • 基金资助:
    中国地质调查局地质调查专题项目“新疆且末县阿克苏河一带构造变形特征及动力学机制研究”(D216080);中国地质调查局地质调查项目(1212011121188)

Detrital Zircon U-Pb Dating and Provenance Analysis for the Triassic Sandstone in Qilianshan Orogen, NE Margin of Tibetan Plateau

WU Long1(), LIU Changfeng2(), LIU Wencan3, ZHANG Hongyuan3   

  1. 1. Hubei Geological Survey, Wuhan, Hubei 430034,China
    2. School of Ocean Sciences, China University of Geosciences, Beijing 100083,China
    3. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
  • Received:2020-06-30 Revised:2021-08-30 Online:2021-10-10 Published:2021-11-04
  • Contact: LIU Changfeng

摘要:

三叠系沉积物广泛覆盖青藏高原东北缘,其中松潘—甘孜地区三叠系的沉积物得到了较系统的研究,但是青藏高原北缘的祁连山三叠系盆地的研究却较为缺乏。为了丰富相关研究和揭示区域构造演化的特点,通过古水流方向统计、砂岩中碎屑矿物统计和碎屑锆石U-Pb测年等方法对祁连山三叠纪盆地物源进行系统研究。结果表明,祁连山三叠系盆地的古流向主要有南东向、正南向、南西向,物源来自岩浆弧和大规模褶皱造山作用的混合区。祁连山三叠系砂岩中的碎屑锆石的年龄谱主要峰值集中在250~290 Ma、360~460 Ma、1 600~2 000 Ma和2 200~2 600 Ma这4个年龄段。通过对比分析华北板块、华南板块中和秦祁昆中央造山带中岩浆锆石年龄谱特征可知:1 600~2 000 Ma和2 200~2 600 Ma年龄段的锆石来自华北板块,360~460 Ma年龄段的锆石来自北祁连造山带,250~290 Ma年龄段的锆石来自东昆仑的火山岛弧。此外,600~1 000 Ma年龄段锆石很少,这些锆石来自扬子板块,表明在三叠纪扬子克拉通和华北克拉通发生碰撞形成了秦岭造山带,阻断了来自扬子克拉通的物源。

关键词: 祁连山, 三叠系砂岩, 碎屑锆石U-Pb定年, 物源分析

Abstract:

Triassic detrital sediments occurring in the northern margin of the Tibetan Plateau, which has been well studied in the Songpan-Ganzi terrane, yet the Triassic basin in the Qilianshan remain poorly understood. In this contribution, we integrated stratigraphy, sedimentology, zircon U-Pb dating on the Triassic sandstones in the Qilianshan to decipher their complex regional tectonic evolution. The results show that the ages of detrital zircons concentrate at four populations in 250-290 Ma,360-460 Ma,1,600-2,000 Ma,and 2,200-2,600 Ma. By comparing with the zircon age spectra in the North China Craton, South China Craton, and the Qinling-Qilian-Kunlun Central Orogenic belt, we suggest that the 1,600-2,000 Ma and 2,200-2,600 Ma zircon age populations were probably sourced from North China Craton, whereas a zircon age population of 360-460 Ma was derived from the North Qilian Orogenic Belt. The 250-290 Ma zircon population may have sourced from the volcanic arc of Eastern Kunlun Orogen in the south. The rare 600-1,000 Ma zircons were probably sourced from the Yangtze Block, since the Triassic North China-Yangtze collision along the Qinling Orogen may have acted as a barrier for the sediments from the Yangtze Block.

Key words: Qilianshan, Triassic sandstone, detrital zircon U-Pb dating, provenance analysis

中图分类号: