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现代地质 ›› 2007, Vol. 21 ›› Issue (4): 675-682.

• 岩石学与矿床学 • 上一篇    下一篇

东秦岭二郎坪群硅质岩地球化学特征及其沉积环境意义

冯胜斌1,2，周洪瑞2，燕长海3，彭翼3，胡绍斌4，任建光2   

  1. 1中国石油 长庆油田公司勘探开发研究院，陕西 西安710021；2中国地质大学 地球科学与资源学院,北京100083；
    3河南省地质调查院，河南 郑州450007；4云南省地质调查院，云南 昆明653100
  • 收稿日期:2007-03-20 修回日期:2007-09-15 出版日期:2007-04-20 发布日期:2007-04-20
  • 作者简介:冯胜斌，男,硕士，1973年出生，古生物学与地层学专业，主要从事沉积地质与矿产研究工作。 Email: fsb_cq@petrochina.com.cn。
  • 基金资助:

    中国地质调查局国土资源大调查项目（199910200227）；中国地质调查局地质调查项目（2003102000015）

The Geochemical Characteristics of Cherts of Erlangping Group in East Qinling and Their Sedimentary Environment Importance

FENG Sheng-bin1,2,  ZHOU Hong-rui2 ,  YAN Chang-hai3,  PENG  Yi3,  HU Shao-bin4, REN Jian-guang2   

  1. 1Research Institute of Exploration and Development of Changqing Oilfield Company, PetroChina, Xi'an,  Shaanxi710021,China;
    2School of Earth Sciences and Resources, China University of Geosciences, Beijing100083,China;
    3Henan Institute of Geological Survey, Zhengzhou, Henan450007,China; 4Yunnan Institute of Geological Survey, Kunming, Yunnan653100,China
  • Received:2007-03-20 Revised:2007-09-15 Online:2007-04-20 Published:2007-04-20

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摘要：

东秦岭二郎坪群硅质岩成因分析对二郎坪群形成环境和构造背景研究具有重要意义。通过对二郎坪群中3类硅质岩地质特征、岩石地球化学特征（w(SiO2)=61.35%~96.01%、N(Si)/N(Al)=2.77~51.53）研究，认为二郎坪群硅质岩为非纯硅质岩；稀土元素的配分模式和特征值（∑REE、∑LREE、∑HREE、δCe、δEu)、常量元素含量（w(Al2O3)、w(TiO2)）和微量元素含量（w(Nb)、w(Rb)、w(Th)）的分析表明研究区硅质岩是热水成因型，但受陆源物质成分影响，陆缘物源对南阳盆地西硅质岩影响较大。地球化学综合分析揭示二郎坪群硅质岩产出于不同海相沉积环境，南阳盆地西硅质岩形成于大陆边缘海环境，而盆地以东硅质岩形成于远洋盆地环境，证实了二郎坪群形成于弧后盆地构造环境。

关键词: 二郎坪群, 硅质岩, 地球化学, 沉积环境, 东秦岭

Abstract:

The genesis study of Erlangping Group is the key to reveal its sedimentary environments and tectonic settings. By studying the geological and geochemical  characteristics(SiO2=61.35%~96.01%，Si/Al=2.77~51.53)of three types of cherts in Erlangping Group in east Qinling orogenic belt，it is believed that the cherts in Erlangping Group are impure silicalite. The normalized REE distribution patterns of chondrite and their characteristic values(∑REE-high，∑LREE-rich， ∑HREE-depletion，negative Eu and Ce anomaly)，the contents of the major elements (Al2O3，TiO2)and the trace elements(Nb，Rb，Th)indicate that the cherts are hydrothermal sediments and have a few continental margin materials， but the cherts formed at the west of Nanyang basin contain more. Comprehensive analysis of geochemical characteristics of cherts shows that the cherts in Erlangping Group are formed in different marine environments， the cherts formed at the west of Nanyang  basin are deposited in continental margin basin environment， and those formed at the east of Nanyang basin are deposited in pelagic environment，so Erlangping Group is marked by back-arc basin setting.

Key words: Erlangping Group, chert, geochemistry, sedimentary environment, East Qinling

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