煤层微量元素分布特征及层位判别意义

Distribution Characteristics of Trace Elements in Coal Seams and Their Implications for Stratigraphic Identification

摘要: 煤中微量元素分布具有层位判别的潜在地球化学价值。以临涣矿区77件主采煤层钻孔煤芯样品为对象，其中5个样品数≥5的主采煤层共62件纳入统计对比。基于13种微量元素数据，采用Pearson相关分析、主成分分析和层次聚类等多元统计方法，系统分析了不同煤层微量元素分布规律、层间差异及其主控因素。结果表明：(1) Ti、Ba、Sr含量最高，Zn、Cu、V和Co的变异系数均大于0.87，结合箱线图显示其层间均值分离明显，是区分不同煤层的潜力指标；(2) 7₂号煤层以Ba-Sr富集为特征，8₁号煤层Ti高值且Pb相对富集，8₂号煤层Cu含量最高，各层呈现可区分的元素组合指纹；(3) 提取的前两个主成分累计解释46.7%的总方差，PC1反映陆源碎屑供给强度，PC2反映沉积环境氧化还原条件变化；(4) 层次聚类进一步揭示7₂号、8₁号煤层的元素组合具有独特性，8₂号与3₂号煤层较为接近。研究区微量元素层间差异受成煤环境氧化还原条件、陆源碎屑供给强度及后期岩浆热液改造三重因素联合控制，微量元素特征可为构造复杂区煤层层位辅助判别提供参考。

Abstract: The distribution of trace elements in coal has potential geochemical value for stratigraphic identification. Based on 77 drill-core coal samples from main minable seams in the Linhuan Mining Area, of which 62 samples from five seams with sample sizes of no less than 5 were included for statistical comparison, this study systematically analyzed the distribution patterns, interlayer differences, and controlling factors of trace elements in different coal seams using multivariate statistical methods including Pearson correlation analysis, principal component analysis (PCA), and hierarchical clustering, based on 13 trace element concentration data. The results show that: (1) Ti, Ba, and Sr exhibit the highest concentrations; the coefficients of variation for Zn, Cu, V, and Co all exceed 0.87, and combined with box plots, their interlayer mean separations are distinct, indicating their potential as indicators for distinguishing different coal seams; (2) the No. 7₂ seam is characterized by Ba-Sr enrichment, the No. 8₁ seam shows high Ti values with relatively enriched Pb, and the No. 8₂ seam has the highest Cu content, each displaying distinguishable elemental assemblage fingerprints; (3) the first two extracted principal components cumulatively explain 46.7% of the total variance, with PC1 reflecting terrigenous detrital supply intensity and PC2 reflecting changes in sedimentary redox conditions; (4) hierarchical clustering further reveals that the No. 7₂ and No. 8₁ seams have distinctive elemental assemblages, while the No. 8₂ and No. 3₂ seams are relatively similar. The interlayer differences of trace elements in the study area are jointly controlled by sedimentary redox conditions, terrigenous detrital input intensity, and post-depositional magmatic-hydrothermal modification. The trace element characteristics can provide references for auxiliary stratigraphic identification of coal seams in tectonically complex areas.