渭北煤田下峪口矿二叠纪煤中稀土元素地球化学研究

运用电感耦合等离子体质谱（ICP MS）对渭北煤田韩城下峪口矿二叠纪主采煤层及其顶底板中的稀土元素进行了测定。在此基础上，全面分析了稀土元素的含量特征和分布模式，探讨渭北煤田二叠纪煤中稀土元素的主要来源及赋存状态。结果表明：与华北和中国煤均值相比，本区煤层中稀土元素相对不富集，∑REY平均含量为87.70 μg/g；剖面上，2号煤中稀土含量稍高于3号煤，3号煤层中自上而下，稀土元素含量呈降低的趋势，在顶底板中出现富集。研究区煤层中轻稀土元素相对于重稀土元素明显富集，Ce呈微弱正异常，成煤沼泽受海水的影响程度较小。Eu明显负异常，且∑REY含量与CaO含量呈负相关关系，说明当时的成煤环境为酸性还原环境。煤层与其顶底板样品中稀土元素分布模式相似，成煤期间物质来源基本一致，陆源物质供应相对稳定。煤中稀土元素含量与灰分呈不太显著的正相关关系（R=0.216），表明煤中稀土元素可能以无机态和有机吸附态共存。

Study on the geochemistry of rare earth elements in the Permian coal from Xiayukou,Weibei Coalfield

The REY(REE+Y) content in the Permian coal seams mined at Xiayukou of Weibei were investigated by inductively coupled plasma mass spectrometry. The content characteristics and distribution patterns of REY were analyzed. Furthermore, the origin and occurrence states of REY were discussed. The results are as follows: compared with mean value of coal in China and North China, the REY are not obviously enriched in this research area with an average of 87.70 μg/g; the mean content of REY in No.2 coal is higher than that of No.3 coal due to the different coal forming micro environment between them; the ∑REY reduced from top to bottom in the No.3 coal seam and enriched in the floor and roof samples; the light REY is obviously enriched compared with the heavy REY. The weak positive anomaly value of Ce indicates that seawater had little influence on the coal swamps. The negative anomaly value of Eu and the negative correlation between ∑REY and CaO indicate the sediment environments were acid reducing environment. The REY distribution patterns in coal, roof and floor seam samples are similar, indicating that they had the same and stable material supply during the coal formation. Positive but insignificant correlation (R=0.216) of ∑REY vs. ash yields demonstrates the possible co existence of inorganic and organic states of REY in coals.