大兴安岭北段宜里地区早侏罗世二长花岗岩U-Pb年龄、地球化学特征及其构造意义
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项目(编号:DD20160047-23)的成果


U-Pb age and geochemical characteristics of the Early Jurassic monzogranite in Yili area,Northern Great Hinggan Mountains,and their tectonic implications
Author:
Affiliation:

Fund Project:

单位:
  • 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:

    本文对大兴安岭北段宜里地区二长花岗岩进行了系统的地球化学及锆石U- Pb同位素年代学研究,旨在查明其成岩时代及岩石成因,并探讨其构造意义。宜里地区二长花岗岩中的锆石均呈半自形—自形,振荡生长环带明显,暗示其岩浆成因。锆石LA- ICP- MS U- Pb同位素定年结果显示,宜里地区二长花岗岩形成于175.8~174.5 Ma,为早侏罗世岩浆事件的产物。岩石具有富硅(SiO2=71. 23%~74.52%)、富碱更富钾(Na2O+K2O=6.31%~8.31%,K2O=2.58%~4.78%)、贫镁(MgO=0.43%~1.50%)、贫钙(CaO=0.91%~1.81%)的特征,铝饱和指数(A/CNK=0.97~1.16),属于准铝质—弱过铝质高钾钙碱性花岗岩。富集Rb、Th、K等大离子亲石元素,相对亏损Nb、Ta等高场强元素和P、Ti等元素,轻重稀土元素分馏较强(La/Yb)N=14.07~50.34,无明显Eu异常(δEu=0.88~1.71)。花岗岩熔体的锆石饱和温度(714~745℃)明显低于A型花岗岩(>800℃),显示出高分异I型花岗岩的特征。岩石学及地球化学特征表明,宜里地区二长花岗岩的形成与俯冲形成的上涌热流加热新增生下地壳发生部分熔融有关。结合区域构造演化及构造判别,认为研究区早侏罗世二长花岗岩形成于蒙古—鄂霍茨克大洋板片南向俯冲作用相关的活动大陆边缘环境。

    Abstract:

    This paper provided LA-ICP-MS zircon U-Pb age,petrographic and geochemical characteristics of the monzogranite in Yili area,northern Great Hinggan Mountains,and discussed the formation age,genesis and geological significance of the rocks.Methods:Based on the field work,through the microscope observation, the whole rock chemical analysis and the LA-ICP-MS zircon U-Pb dating of monzogranite in Yili area.Results:Zircons from two representative intrusive rocks are euhedral—subhedral in shape and display oscillatory growth zoning in CL images,implying their magmatic origin.The dating results indicate that the monzogranites formed in the Early Jurassic during the age of 175.8~174.5 Ma,suggesting the Early Jurassic in age.The granites are characterized by high silicon (SiO2=71.23%~74.52%),high alkali and potassium(Na2O+K2O=6.31%~8.31%,K2O=2.58%~4.78%),low magnesium(MgO=0.43%~1.50%),low calcium(CaO=0.91%~1.81%),and A/CNK ratios ranging from 0.97 to 1.16.The granites are generally enriched in large ion lithophile elements(LILEs),such as Rb,K,Th,and relatively depleted in heavy rare earth elements(HREEs)and high field strength elements(HFSEs),such as Nb,Ta P,Ti,with(La/Yb)N ratios of 14.07~50.34.No obvious negative Eu anomalies(δEu=0.88~1.71)have been identified.Zircon saturation temperatures(714~745℃) are significantly lower than Cretaceous A-type granites(>800℃).Conclusions:Collectively,it is suggested that these granites belong to quasi aluminum-weak peraluminous and high-K calc-alkaline I-type ones.The petrological and geochemical features indicate that their primary magmas are derived from partial melting of the juvenile lower crust.Considering the background of regional tectonic evolution,it is suggested that the Early Jurassic monzonite granite from the Yili area formed in an active continental margin setting related to the southward subduction of the Mongol—Okhotsk oceanic plate.

    参考文献
    相似文献
    引证文献
引用本文

骆念岗,高莲凤,张璟,张振国,尹志刚,谢忠,崔建宇,吴子杰.2021.大兴安岭北段宜里地区早侏罗世二长花岗岩U-Pb年龄、地球化学特征及其构造意义[J].地质论评,67(6):1649-1669,[DOI].
LUO Niangang, GAO Lianfeng, ZHANG Jing, ZHANG Zhenguo, YIN Zhigang, XIE Zhong, CUI Jianyu, WU Zijie.2021. U-Pb age and geochemical characteristics of the Early Jurassic monzogranite in Yili area, Northern Great Hinggan Mountains, and their tectonic implications[J]. Geological Review,67(6):1649-1669.

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:2021-03-15
  • 最后修改日期:2021-06-23
  • 录用日期:
  • 在线发布日期: 2021-11-19
  • 出版日期: 2021-11-15