三塘湖盆地二叠系芦草沟组油页岩微量元素和稀土元素地球化学特征

Geochemical characteristics of trace elements and Rare earth elements in Permian Lucaogou oil shale,Santanghu Basin

  • 摘要: 三塘湖盆地二叠系芦草沟组油页岩发育于石头梅凸起附近,位于三塘湖盆地西南缘。通过电感耦合等离子体质谱仪(ICP-MS)对油页岩中微量元素和稀土元素地球化学特征进行研究。研究表明:和中国煤相比研究区油页岩中比较富集V,Cr,Ni,Cu,Ge,As,Se,Rb,Sr,Mo,Cd,Sb,有毒元素、致癌元素Cd,Ni,As,Cd等含量明显高于地壳和中国煤中平均含量;REE富集情况低于北美页岩水平,稀土元素分布模式表明LREE明显富集,HREE相对亏损,Eu随深度正负异常变化频繁。δCe,δEu,Sr/Ca,Sr/Ba,V/(V+Ni)及V/Cr的值总体上反映出该区油页岩形成于贫氧-缺氧,水体盐度咸水-淡水的较深水环境

     

    Abstract: The Permian Lucaogou Formation oil shale in Santanghu Basin was developed near the Shitoumei uplift,lo- cated in the southwestern margin of the Santanghu Basin. The geochemical characteristics of trace elements and rare earth elements in the selected oil shale samples from the Santanghu area were measured by using inductively-coupled plasma mass spectrometer(ICP-MS)technique. The results show that the content of some elements,such as V,Cr,Ni, Cu,Ge,As,Se,Rb,Sr,Mo,Cd and Sb,in this studied area are higher than that in the Chinese coals,and also some toxic elements and Carcinogenic element (e. g. Cd,Ni,As,Cd) are obvious higher than that in the earth crust and the average content of the Chinese coals. The average contents of REE is lower than that in the North American Shale Composite (NASC),and the REE distribution patterns shows that the samples of the selected area has an obvious en- richment of the light rare earth elements (LREEs),than that of the heavy rare earth elements (HREEs),with Eu fre- quency changes with depths,reflecting a strong fractional degree among LREEs and a slight fractional degree among HREEs. On the whole,the value of δCe,δEu,Sr / Ca,Sr / Ba,V / ( V+Ni) and V / Cr indicate that the oil shale in this area was developed in oxygen poor to deficit condition,and reflect that the oil shale in this area was deposited in a rel- ative deeper-water environment with salinity water.

     

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