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现代地质 ›› 2004, Vol. 18 ›› Issue (3): 339-345.

• 岩石.矿物.矿床 • 上一篇    下一篇

湘东北涧溪冲变质火山岩的Sm-Nd同位素年龄及其成因

伍光英1,2,李金冬1,3,车勤建1,3,肖庆辉1,唐晓珊3,彭和求3   

  1. 1.中国地质大学地球科学与资源学院,北京100083;2.宜昌地质矿产研究所,湖北宜昌4430033.湖南省地质矿产勘查开发局,湖南长沙410011
  • 收稿日期:2004-04-01 修回日期:2004-05-31 出版日期:2004-03-20 发布日期:2004-03-20
  • 作者简介:伍光英,男,高级工程师,博士研究生,1965年出生,矿物学、岩石学、矿床学专业,从事基础地质的调查研究工作。
  • 基金资助:

    中国地质调查局基础地质计划项目(1212 010310206);中国地质调查局区域地质调查工作项目(200013000107)。

Sm-Nd DATING AND GENESIS OF THE JIANXICHONG GROUP METAMORPHIC VOLCANIC ROCKS IN NORTHEAST HUNAN

WU Guang-ying1,2,LI Jin-dong1,3,CHE Qin-jian1,3,XIAO Qin-hui1,TANG Xiao-shan3,PENG He-qiu3
  

  1. 1.China University of Geosciences,Beijing  100083,China
    2.Yichang Institute of Geology and Mineral Resources,Yichang,Hubei  443003,China
    3.Hunan Bureau of Geology and Mineral Resources Exploration and Development,Changsha,Hunan  410011,China
  • Received:2004-04-01 Revised:2004-05-31 Online:2004-03-20 Published:2004-03-20

摘要:

最近的区域地质调查研究发现,湘东北地区原中元古代冷家溪群实际上应划分为4部分,它们均形成于不同的时代和不同的构造环境,将其中分离出的最老的基本无序的变质沉积一火山岩系建立为“涧溪冲岩群”。根据其岩石学、岩石地球化学及同位素年代学等方面的研究认为:“涧溪冲岩群”是变质火山岩夹变质粘土质沉积岩经构造叠置起来的变质岩系,属绿片岩相一高绿片岩相。变质火山岩的Sm-Nd全岩等时线年龄为(2594±48)Ma,其形成的地质时代可能是新太古代。变质火山岩的原岩为在大洋拉张环境下形成的以拉斑玄武岩为主、钙碱性玄武岩次之的火山一次火山岩系,其物源为亏损地幔。

关键词: Sm-Nd年龄, 构造环境, 新太古代, “涧溪冲岩群”, 湘东北

Abstract:

Recent regional geologic investigations show that the original“Mesoproterozoic Lengjiaxi Group”in northeast Hunan should be divided into four parts,they were formed at different ages and in different tectonic settings.“Jianxichong Group”is the oldest one among them.They belong to metamorphic volcanic-sedimentary series.According to the study of petrology,geochemistry and isotopic geochronology,we conclude that the volcanic rocks series mainly belong to tholeiites basalt and a little belong to calc-alkaline series.The whole rock Sm-Nd age of the mafic-ultramafic volcanic rocks is(2,594±48)Ma,it belongs to Neoarchean.The metamorphic facies of those rocks belong to blues chist facies.The source of the mafic-ultramafic volcanic rocks is depleted mantle.And their tectonic settings are the ocean or ocean island.

Key words: Sm-Nd dating, tectonic setting, Neoarchean, the Jianxichong Group, northeast Hunan

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