| 内蒙古阿拉善右旗雅干地区二叠系埋汗哈达组硅质岩成因及其沉积环境 |
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| 引用本文： | 史冀忠,卢进才,魏建设,牛亚卓,韩小锋,张宇轩.内蒙古阿拉善右旗雅干地区二叠系埋汗哈达组硅质岩成因及其沉积环境[J].吉林大学学报(地球科学版),2018,48(6):1711-1724. |
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| 作者姓名： | 史冀忠 卢进才 魏建设 牛亚卓 韩小锋 张宇轩 |
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| 作者单位： | 中国地质调查局西安地质调查中心, 西安 710054 |
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| 基金项目： | 中国地质调查局项目（DD20160172）；国家自然科学基金项目（41402097） |
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| 摘 要： | 通过对内蒙古阿拉善右旗雅干地区好比如、杭乌拉剖面二叠系埋汗哈达组硅质岩岩石学特征、主量元素、稀土元素地球化学研究，探讨了硅质岩的成因及其沉积环境。地球化学测试结果显示：好比如剖面硅质岩SiO2质量分数为89.83%~94.16%，平均值为92.01%，Al/（Al+Fe+Mn）值为0.49~0.65，平均值为0.56，δCe值为0.87~0.92，平均值为0.89；杭乌拉剖面硅质岩SiO2质量分数为75.93%~90.14%，平均值为86.70%，Al/（Al+Fe+Mn）值为0.68~0.78，平均值为0.73，δCe值为0.89~0.94，平均值为0.90；在Al-Fe-Mn三角图上，样品全部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。好比如剖面硅质岩Al2O3/（Al2O3+Fe2O3）值为0.59~0.78，平均值为0.71，MnO/TiO2值为0.17~0.88，平均值为0.41，（La/Ce）N值为1.07~1.25，平均值为1.16，Ceanom值为-0.059~-0.026，平均值为-0.043；杭乌拉剖面硅质岩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；在硅质岩沉积环境判别图上，样品落在大陆边缘型硅质岩区域内，指示研究区硅质岩沉积于大陆边缘缺氧的水体环境。综合分析认为研究区早二叠世为大陆边缘滨海-浅海相沉积环境。
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| 关 键 词： | 阿拉善右旗 二叠系 硅质岩 地球化学 沉积环境 |
| 收稿时间： | 2018-01-25 |
Petrogenesis and Sedimentary Environment of Permian Maihanhada Formation Cherts in Yagan Region of Alxa Right Banner,Inner Mongolia |
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| Shi Jizhong,Lu Jincai,Wei Jianshe,Niu Yazhuo,Han Xiaofeng,Zhang Yuxuan.Petrogenesis and Sedimentary Environment of Permian Maihanhada Formation Cherts in Yagan Region of Alxa Right Banner,Inner Mongolia[J].Journal of Jilin Unviersity:Earth Science Edition,2018,48(6):1711-1724. |
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| Authors: | Shi Jizhong Lu Jincai Wei Jianshe Niu Yazhuo Han Xiaofeng Zhang Yuxuan |
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| Institution: | Xi'an Center, China Geological Survey, Xi'an 710054, China |
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| Abstract: | The authors discussed the petrogenesis and sedimentary environment of the Permian cherts from the Maihanhada Formation in Haobiru and Hangwula sections of Alxa Right Banner according to the study of the petrologic characteristics,major and rare earth elements. The geochemical test results show that the SiO2 content of the cherts from Haobiru Section is 89.83%-94.16%,with an average of 92.01%;Al/(Al+Fe+Mn) ratio is 0.49-0.65,with an average of 0.56;δCe value is 0.87-0.92,with an average of 0.89. The SiO2 content of the cherts from Hangwula Section is 75.93%-90.14%,with an average of 86.70%;Al/(Al+Fe+Mn) ratio is 0.68-0.78, with an average of 0.73; δCe value is 0.89-0.94, with an average of 0.90. In the Al-Fe-Mn triangular graph, the dots fall into the biochemically deposited area,which indicates its biochemical origin. On the other hand,Al2O3/(Al2O3+Fe2O3)value from Haobiru Section is 0.59-0.78,with an average of 0.71;MnO/TiO2 value is 0.17-0.88,with an average of 0.41;(La/Ce)N value is 1.07-1.25,with an average of 1.16; Ceanom value is -0.059——0.026,with an average of -0.043; Al2O3/(Al2O3+Fe2O3) value from Hangwula Section is 0.78-0.86,with an average of 0.83;MnO/TiO2 value is 0.04-0.40,with an average of 0.16;(La/Ce)N value is 1.02-1.15, with an average of 1.10;Ceanom value is -0.041——0.001, with an average of -0.029. In the discrimination plot of sedimentary environment of cherts,the rocks fall in the continental margin,indicating that the cherts in the study area were deposited in an oxygen-deficient environment. Based on the comprehensive analysis,it can be inferred that the sediments in the study area had been deposited in a coastal shallow marine environment in the continental margin during Early Permian. |
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| Keywords: | Alxa Right Banner Permian chert geochemistry sedimentary environment |
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