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现代地质 ›› 2019, Vol. 33 ›› Issue (04): 691-702.DOI: 10.19657/j.geoscience.1000-8527.2019.04.01

• 岩石学、矿物学、矿床学 • 上一篇    下一篇

秦昆结合部塔秀地区隆务河组碎屑锆石LA-ICP-MSU-Pb年代学及其地质意义

路宗悦1,2, 余心起1(), 刘满年2, 张振2, 魏立勇2, 赵常存2, 郑鑫2, 寇少磊2, 许安民2, 王照翻1   

  1. 1.中国地质大学 (北京) 地球科学与资源学院,北京 100083
    2.原中国人民武装警察部队 黄金第五支队,陕西 西安 710100
  • 收稿日期:2018-10-11 修回日期:2019-01-16 出版日期:2019-08-20 发布日期:2019-09-05
  • 通讯作者: 余心起
  • 作者简介:余心起,男,教授,博士生导师,1962年出生,构造地质学专业,主要从事应用构造地质学研究。Email: yuxinqi@cugb.edu.cn
    路宗悦,男,硕士研究生,1992年出生,构造地质学专业,主要从事区域构造地质学研究。Email: luzongyue2@163.com
  • 基金资助:
    中国地质调查局项目“中亚地区能源潜力调查分析”(121201104000150014);中国地质调查局项目“青海海南州塔秀—曲什安地区1∶5万区域地质矿产调查”(1212011220660)

LA-ICP-MS U-Pb Geochronology of Detrital Zircons from the Longwuhe Formation in Taxiu Area, the Junction Area Between the Qinling and Kunlun Orogenic Belts

LU Zongyue1,2, YU Xinqi1(), LIU Mannian2, ZHANG Zhen2, WEI Liyong2, ZHAO Changcun2, ZHENG Xin2, KOU Shaolei2, XU An’min2, WANG Zhaofan1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    2. Former No.5 Gold Geological Party, CAPF, Xi’an, Shaanxi 710100, China
  • Received:2018-10-11 Revised:2019-01-16 Online:2019-08-20 Published:2019-09-05
  • Contact: YU Xinqi

摘要:

秦昆结合部独特的地质组成与复杂的造山带结构受到广泛关注。前人对该地区沉积物质来源进行了初步分析,但存在较大争议。选取隆务河组碎屑岩为研究对象,运用碎屑锆石LA-ICP-MS U-Pb同位素年代学方法,探讨隆务河组物源特征。U-Pb测年结果表明,隆务河组碎屑锆石年龄谱明显分为4组:2 746~2 084 Ma,1 094~775 Ma,492~411 Ma,372~237 Ma。其中,372~237 Ma年龄组约占总体的56.79%,所占比例最大,年龄相对集中,且呈现出强烈的峰值,代表了阿尼玛卿洋向北俯冲碰撞产生的一系列构造岩浆事件,其余年龄段所占比例则较少。综合分析显示,隆务河组碎屑沉积物质来源较为复杂,具有明显的多元性,存在祁连造山带、柴北缘构造带和东昆仑造山带3个物源区,其中东昆仑造山带提供了大部分物源,为隆务河组贡献最大的物源区。

关键词: 物源, 隆务河组, 碎屑锆石, LA-ICP-MS锆石U-Pb年龄, 秦昆结合部

Abstract:

The junction area between the Qinling and Kunlun orogenic belts has received wide attention for its unique geological compositions and complex orogenic structures. The preliminary analysis has been performed previously on the provenance of sediments in this area but still remained controversy. This paper selects clastic rocks from the Longwuhe Formation and uses LA-ICP-MS U-Pb ages of detrital zircons to restrict their provenance characteristics. Our results show that the zircon U-Pb ages can be divided into four groups, i.e., 2 746-2 084 Ma, 1 094-775 Ma, 492-411 Ma and 372-237 Ma. Among them, the 372-237 Ma group accounts for 56.79% of the total. This largest proportion age group is relatively concentrated with a evident peak, representing a series of tectonic magma events caused by the subduction of the A’nyemaqen ocean. The comprehensive analysis reveals that the sources of clastic sediments in the Longwuhe Formation are complex and diverse, including the northern margin of the Qaidam Basin, the Qilian orogenic belt and the Eastern Kunlun orogenic belt. The Eastern Kunlun orogenic belt is the largest provenance area of the Longwuhe Formation and provides most sedimentary materials.

Key words: provenance, the Longwuhe Formation, detrital zircon, LA-ICP-MS zircon U-Pb age, the junction area between Qinling and Kunlun orogenic belts

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