史冀忠, 卢进才, 魏建设, 牛亚卓, 姜亭, 韩小锋, 许伟. 银额盆地及邻区二叠系硅质岩岩石学、地球化学特征及沉积环境[J]. 地质通报, 2018, 37(1): 120-131.
    引用本文: 史冀忠, 卢进才, 魏建设, 牛亚卓, 姜亭, 韩小锋, 许伟. 银额盆地及邻区二叠系硅质岩岩石学、地球化学特征及沉积环境[J]. 地质通报, 2018, 37(1): 120-131.
    SHI Jizhong, LU Jincai, WEI Jianshe, NIU Yazhuo, JIANG Ting, HAN Xiaofeng, XU Wei. Petrology, geochemistry and sedimentary environment of Permian siliceous rocks in Yingen-Ejin basin and its adjacent areas[J]. Geological Bulletin of China, 2018, 37(1): 120-131.
    Citation: SHI Jizhong, LU Jincai, WEI Jianshe, NIU Yazhuo, JIANG Ting, HAN Xiaofeng, XU Wei. Petrology, geochemistry and sedimentary environment of Permian siliceous rocks in Yingen-Ejin basin and its adjacent areas[J]. Geological Bulletin of China, 2018, 37(1): 120-131.

    银额盆地及邻区二叠系硅质岩岩石学、地球化学特征及沉积环境

    Petrology, geochemistry and sedimentary environment of Permian siliceous rocks in Yingen-Ejin basin and its adjacent areas

    • 摘要: 通过对研究区二叠系硅质岩岩石学特征、主量及稀土元素地球化学研究,探讨硅质岩的地球化学特征及其沉积环境。结果表明,杭乌拉下二叠统埋汗哈达组硅质岩Al/(Al+Fe+Mn)值介于0.68~0.78之间,平均值为0.73,δCe值为0.89~0.94,平均值为0.90,二断井中二叠统菊石滩组Al/(Al+Fe+Mn)值介于0.50~0.67之间,平均值为0.60,δCe值介于0.85~0.90之间,平均值为0.88,在Al-Fe-Mn三角图上,样品点落入生物成因硅质岩区,指示研究区硅质岩为海水生物沉积成因。杭乌拉下二叠统埋汗哈达组硅质岩Al2O3/(Al2O3+Fe2O3)值为0.78~0.86,平均值为0.83,MnO/TiO2值为0.04~0.40,平均值为0.16,(La/Ce)N值为1.02~1.15,平均值为1.10,Ceanom值为-0.041~-0.001,平均值为-0.029,二断井中二叠统菊石滩组硅质岩Al2O3/(Al2O3+Fe2O3)值为0.82~0.91,平均值为0.87,MnO/TiO2值为0.05~0.47,平均值为0.24,(La/Ce)N值为1.00~1.12,平均值为1.06,Ceanom值为-0.058~-0.033,平均值为-0.045。这些地球化学指标指示了研究区硅质岩沉积于大陆边缘缺氧的水体环境中。

       

      Abstract: The geochemical characteristics and depositional environment of Permian siliceous rocks were studied based on the petrological characteristics, major elements and rare earth elements. According to the test results, Hangwula sectional siliceous rocks' Al/(Al+Fe+Mn)values are 0.68~0.78, with an average of 0.73; δCe values are 0.89~0.94, with an average of 0.90; Erduanjing sectional siliceous rocks' Al/(Al+Fe+Mn)values are 0.50~0.67, with an average of 0.60; δCe values are 0.85~0.90, with an average of 0.88. In the Al-Fe-Mn triangular diagram, samples fall into biochemically-deposited area, which indicates a biochemically-deposited origin for these rocks. Hangwula sectional siliceous rocks' Al2O3/(Al2O3+Fe2O3)values are 0.78~0.86, with an average of 0.83; MnO/TiO2 values are 0.04~0.40, with an average of 0.16;(La/Ce)N values are 1.02~1.15, with an average of 1.10; Ceanom values are -0.041~-0.001, with an average of -0.029. Erduanjing sectional siliceous rocks' Al2O3/(Al2O3+Fe2O3)values are 0.82~ 0.91, with an average of 0.87; MnO/TiO2 values are 0.05~0.47, with an average of 0.24;(La/Ce)N values are 1.00~1.12, with an average of 1.06; Ceanom values are -0.058~-0.033, with an average of -0.045. All these geochemical characteristics suggest that these siliceous rocks were deposited in a continental margin setting where the sea water in the period of deposition was under an anoxic condition.

       

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