内蒙古阿鲁科尔沁旗林西组泥岩地球化学特征及构造意义
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本文为中国地质调查局项目(编号1212010782001,1212011120970,1212011220906)资助成果。


Geochemical characteristics of mudstone from the Late Permian Linxi Formation in Alukeerqin Qi, Inner Mogolia and its structural significance
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    摘要:

    阿鲁科尔沁旗陶海营子剖面以灰、灰黑、黄绿色的砂板岩组合为特征,是林西组典型剖面之一,含双壳、叶肢介、植物和孢粉化石,结合碎屑锆石年龄,时代为晚二叠世晚期。本次所研究的林西组样品以暗色泥岩为主,主量元素平均含量SiO2=62. 90%,Al2O3=16. 85%,MgO=1. 78%,CaO=1. 01%,Na2O=1. 64%,K2O=4. 0%,K2O/Na2O为1. 10~5. 66;A12O3/(CaO+Na2O)比值为3. 57~12. 69;稀土元素ΣREE介于139. 85×10-6~231. 65×10-6之间,平均值为190. 74×10-6,δEu值介于0. 49~0. 87之间,平均值为0. 61,表现为铕的负异常,Ce介于0. 91×10-6~0. 96×10-6之间,为负异常,LREE富集,HREE亏损,微量元素以亏损Nb、Ta、Sr,富集Rb、Ba、La、Ce、Pb、Nd、Sm为特征。以上分析表明林西组形成于靠近大陆岛弧的活动大陆边缘构造背景。依据碎屑锆石年龄谱值信息,林西组沉积物源具多样性和复杂性,除东北各地块,同时存在华北板块和西伯利亚板块的物源信息,说明林西组沉积时期华北板块与西伯利亚板块可能已经开始俯冲过程。

    Abstract:

    The Taohaiyingzi section of the Linxi Formation in Alukeerqin Qi, Inner Mongolia, is one of the typical sections in northeastern China. It consists mainly of black and grayblack sandstone and slate. The newly found conchostracans, pollen and spores, along with the detrital zircon age, suggest that the section is late Late Permian in age. The samples from the Linxi Formation are dominantly dark mudstones. The major chemical compositions are SiO2 62. 90%, Al2O316. 85%, MgO 1. 78%, CaO 1. 01%, Na2O 1. 64%,K2O 4. 0%, K2O/Na2O between 1. 10 and 5. 66, A12O3/(CaO+Na2O) between 3. 57 and 12. 69. The ΣREE ranges from 139. 85×10-6 to 231. 65×10-6, with an average of 190. 74. δEu ranges from 0. 49 to 0. 87, with an average of 0. 61. δCe ranges from 0. 91 to 0. 96. The clastic rocks are characterized by LREE enrichment and HREE depletion. Trace elements are characterized by depletion of Nb, Ta, Sr, enrichment of Rb, Ba, La, Ce, Pb, Nd and Sm. The analysis above shows that the Linxi Formation formed in the active continental marginal structural background near the continental island arc. Based on detrital zircon age, the sediment sources of the Linxi Formation are diverse and complex. Besides the blocks in the northeast, provenance information also points to the North China plate and the Siberia plate at the same time, suggesting that the North China plate and the Siberia plate may have started subducting process during the deposition period of the Linxi Formation.

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张海华,张健,苏飞,黄欣,郑月娟,陈树旺,公繁浩.2019.内蒙古阿鲁科尔沁旗林西组泥岩地球化学特征及构造意义[J].地质学报,93(5):1125-1136.
ZHANG Haihua, ZHANG Jian, SU Fei, HUANG Xin, ZHENG Yuejuan, CHEN Shuwang, GONG Fanhao.2019. Geochemical characteristics of mudstone from the Late Permian Linxi Formation in Alukeerqin Qi, Inner Mogolia and its structural significance[J]. Acta Geologica Sinica,93(5):1125-1136.

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  • 收稿日期:2018-03-17
  • 最后修改日期:2018-08-16
  • 录用日期:2018-08-22
  • 在线发布日期: 2018-11-26
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