地学前缘 ›› 2012, Vol. 19 ›› Issue (5): 205-224.

• 论文 • 上一篇    下一篇

祁连造山带东段早古生代葫芦河群变质碎屑岩中碎屑锆石LA-ICP-MS U-Pb年龄：源区特征和沉积时代的限定

裴先治，李佐臣，李瑞保，裴磊，刘成军，高景民，魏方辉   

  1. 1. 西部矿产资源与地质工程教育部重点实验室， 陕西 西安 710054
    2. 长安大学 地球科学与资源学院， 陕西 西安 710054
    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:2012-06-10 修回日期:2012-06-18 出版日期:2012-09-10 发布日期:2012-09-10
  • 作者简介:裴先治（1963—），男，博士，教授，博士生导师，构造地质学专业，主要从事构造地质学和区域地质学研究。E-mail：peixzh@sina.com
  • 基金资助:

    国家自然科学基金项目（40972136，41172186，40572121）；中国高等学校博士学科点专项科研基金项目（20110205110004）；中央高校基本科研业务费专项资金项目（CHD2011TD020）；中国地质调查局地质调查项目（200013000154）

 LA-ICP-MS U-Pb ages of detrital zircons from the metadetrital rocks of the Early Palaeozoic Huluhe Group in eastern part of Qilian orogenic belt: Constraints of material source and sedimentary age.

  1. 1. Key Laboratory of Western China’s Mineral Resources and Geological Engineering, Ministry of Education, Xi’an 710054, China
    2. College of Earth Science and Resources, Chang’an University, Xi’an 710054, China
    3. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
  • Received:2012-06-10 Revised:2012-06-18 Online:2012-09-10 Published:2012-09-10

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摘要：

祁连造山带东段葫芦河群的形成时代长期存在争议。选择葫芦河群变质碎屑岩为研究对象，运用LAICPMS锆石UPb同位素年代学方法，探讨葫芦河群的形成时代和物源特征。结果表明，葫芦河群的2个样品碎屑锆石同位素年龄数据以及侵入其中的花岗岩同位素年龄表明，葫芦河群沉积时代限定为447～434 Ma，其主体形成时代为早志留世。葫芦河群变质碎屑锆石年龄谱明显分为4组：（1）震旦纪—早古生代年龄组，426～595 Ma，峰值为479 Ma；（2）新元古代年龄组，738～981 Ma，峰值为887 Ma；（3）中元古代年龄组，1 000～1 913 Ma，峰值为1 499 Ma；（4）古元古代—新太古代年龄组，2 053～2 872 Ma，峰值为2 448 Ma。其中，早古生代年龄组可进一步细分为426～493 Ma和527～595 Ma两个年龄段，峰值分别为445  Ma和559 Ma，前者年龄段指示其物源可能以邻近地区的北祁连造山带和西秦岭北缘构造带为主，是加里东期中南祁连和西秦岭微地块分别向北俯冲、碰撞产生的一系列火成岩在造山剥蚀后的沉积响应；后者年龄段则与北祁连造山带和西秦岭北缘构造带中泛非造山事件中的岩浆活动有关。新元古代年龄组可细分为738～799 Ma、839～862 Ma和902～981 Ma 3个年龄段，峰值分别为768 Ma、848 Ma和948 Ma，以902～981 Ma年龄组为主；第一年龄段（738～799 Ma）与北祁连造山带新元古代晚期岩浆事件的年龄大致相对应，与Rodinia超大陆的裂解事件相关；第二年龄段和第三年龄段（839～862 Ma、902～981 Ma）与中祁连地区和西秦岭北缘的新元古代早期构造岩浆事件年龄大致相对应，与Rodinia超大陆汇聚事件及岛弧型岩浆作用相关。中元古代年龄组可细分为1 000～1 197 Ma和1 243～1 913 Ma 2个年龄段，峰值分别为1 036 Ma和1 593 Ma，其物源可能来自祁连造山带和华北板块基底岩系。古元古代—新太古代年龄组反映了物源来自北祁连造山带和西秦岭北缘构造带的结晶基底，部分物源也有可能来自于华北板块基底岩系。综合分析显示，葫芦河群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、西秦岭北缘构造带和华北板块基底3个物源区，其中祁连造山带和西秦岭北缘构造带提供了大部分物源，而祁连造山带应为葫芦河群贡献最大的物源区。

关键词: 关键词：碎屑锆石, LA-ICP-MS锆石U-Pb年龄, 物源, 葫芦河群, 祁连造山带

Abstract:

Abstract: There was much controversy for long over the formation age of the Huluhe Group in eastern part of Qilian orogenic belt. Choosing the metadetrital rocks in the Huluhe Group as study objects, this article uses LAICPMS zircon UPb isotope chronology to study the formation age and material source of the Huluhe Group. The results show that the detrital zircons isotope ages of the two samples from the Huluhe Group and the age of the granite intruded in it show that the sedimentary age of the Huluhe Group ranges from 447434 Ma, mainly the early Silurian. The zircon age spectrum can evidently divided into four groups: SinianEarly Paleozoic age group from 426595 Ma, the peak value is 479 Ma; Neoproterozoic age group from 738981 Ma, the peak value is 887 Ma; Mesoproterozoic age group from 10001913 Ma, the peak value is 1499 Ma; PaleoproterozoicNeoarchaean age group from 20532872 Ma, the peak value is 2448 Ma. The SinianEarly Paleozoic age group can further be divided into 426493 Ma and 527595 Ma, the peak values are 445 Ma and 559 Ma respectively. The former indicates that its material source mainly be the adjacent North Qilian orogenic belt and northern margin of the West Qinling tectonic zone, which is a sedimentary response to the orogenic erosion of a series of igneous rocks caused by the northward subduction and collision of the MiddleSouth Qilian and West Qinling microblock in the Caledonian, respectively. The latter is related to the magmation of the FanAfrican orogenic event in the North Qilian orogenic belt and northern margin of West Qinling tectonic zone. The Neoproterozoic age group can further be divided into 738799 Ma, 839862 Ma and 902981 Ma, the peak values are 768 Ma, 848 Ma and 948 Ma respectively, and 902981 Ma age datas have the largest proportion. The 738799 Ma age datas are approximately corresponding to the age of Late Neoproterozoic tectonomagmatic event in the North Qilian orogenic belt, and are related to the breakup of the supercontinent Rodinia. The 839862 Ma and 902981 Ma age datas are approximately correponding to the age of Early Neoproterozoic tectonomagmatic event in Middle Qilian and northern margin of West Qinling area, and are related to the convergence of the supercontinent Rodinia and arc magamtism. The Mesoproterozoic age group can be divided into 10001197 Ma and 12431913 Ma, the peak values are 1036 Ma and 1593 Ma respectively, and its material source may be the basement of Qilian orogenic belt and North China block. The PaleoproterozoicNeoarchaean age group reflects that the material source is the crystalline basement of North Qilian orogenic belt and northern margin of West Qinling tectonic belt, part may also be from the basement of North China block. Comprehensive analyses show that the material source is much complicated, with obvious diversity, including the Qilian orogenic belt, northern margin of West Qinling tectonic zone and the basement of North China block, among which the first two was the predominate source areas to the sediments, but Qilian orogenic belt is the main source of the Huluhe group.

Key words: detrital zircon, LA-ICP-MS zircon U-Pb age, material source, Huluhe Group, Qilian orogenic belt

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