沁水盆地晚古生代煤中稀土元素地球化学特征

摘要：研究煤中稀土元素对分析成煤环境具有重要意义。运用电感耦合等离子质谱、X射线荧光光谱、X射线衍射等方法分析了沁水盆地晚古生代煤及其顶底板炭质泥岩、粉砂岩、灰岩和黄铁矿脉中稀土元素的地球化学特征，探讨了煤中稀土元素的赋存特征及富集成因。结果表明，沁水盆地晚古生代煤中稀土元素含量整体较低，剖面上太原组煤中稀土元素的含量大于山西组，平面上具有南高北低的分布特征。煤中稀土元素主要赋存在粘土矿物和黄铁矿中，碳酸盐矿物和氧化物中稀土元素含量较低，相当部分的稀土元素赋存在有机质中。相关分析表明，稀土元素与Si、Al关系密切。研究认为，沁水盆地煤中稀土元素的富集受控于聚煤古环境，煤层及其顶底板岩石中稀土元素的来源具有一致性，成煤时期海水对泥炭沼泽的影响导致太原组煤中相对富集重稀土，但没有导致Ce的亏损。

Geochemistry characteristics of rare earth elements in the late Paleozoic coal from Qinshui Basin

Abstract: The study of rare earth elements (REE) in coal is of great significance to analyze coal-forming environment. Geochemistry characteristics of REE in late Paleozoic coal and roof and floor rocks including carbon mudstone, siltstone, limestone and veined pyrite from Qinshui Basin are analyzed using inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry and X-ray diffraction. Occurrence mode of REE and their geological origin are discussed based on geological parameters of REE. The results show that the content of REE in coal from Qinshui Basin is lower than the average content of REE in Chinese coals. The content of REE in coal of Taiyuan formation is higher than that of Shanxi formation. Horizontal distribution of REE shows that the content of REE in southern part of Qinshui Basin is higher than that in the northern part. REE in coal mainly occurs in clay minerals and pyrite, and the contents of REE in carbonate minerals and oxides are relatively low. Furthermore, quite a part of the REE in coal occurs in organic matter. Correlation analysis indicates that REE is highly correlated to the content of Si and Al. It is suggested that the enrichment of REE in coal from Qinshui Basin is controlled by coal-forming environment and the source of REE in coal and roof and floor rocks are consistent. The influence of sea water on the peat bog lead to higher heavy REE in coal of Taiyuan formation but it didn’t result in negative anomaly of Ce.