This study focuses on determining mineralogical and elemental compositions of coal seams (to the upwards, D, C, B, A, and S0) within seven coal exploration wells from the Alpu coalfield (Eskişehir, Central Türkiye). Furthermore, the special goal of the study is a comparative analysis of the relations between the elements by using agglomerative hierarchical clustering algorithm with different linkage methods as well as different similarity measures. Clay minerals and quartz are commonly detected as abundant to dominant phases, while natural zeolite formations were detected in the studied seams C, B, A, and S0. The SEM-EDX data shows that clinoptilolites in zeolite minerals were observed within the organic matter, while crystalline and non-crystalline analcime minerals along with syngenetic authigenic rhomboid K-feldspars were only detected in the seam A from one studied well. The existence of some micron-sized minerals such as apatite, monazite, and Ti-oxides within the smectite matrix and the measurable amount of Ti in smectite imply that alteration of epiclastic and contemporaneous volcanic inputs was developed under weak acidic to neutral conditions during peat accumulation. The lack of natural zeolite and carbonate minerals in the seam D could be an indicator of weak acidic to neutral conditions and semi-closed hydrogeological conditions. Nevertheless, the alkalinity of mire water, water table, and hydrogeological regime seem to be variable during the accumulation of precursor peats of seams C, B, A, and S0. In turn, alteration of volcanic inputs was observed under neutral to weak alkaline conditions and semi-closed to closed hydrogeological regime. Hence, syngenetic authigenic, micron-sized clinoptilolites were formed. Moreover, the existence of authigenic rhomboid K-feldspars and syngenetic authigenic analcimes in certain exploration well could suggest local increases on dissolved Na⁺ concentrations, alkalinity, and water table. Except for volcanogenic origin for minerals, accessory micron-sized minerals, like chromite, pentlandite, and allanite grains presumably originated from clastic influxes of ophiolitic rocks in the basement into palaeomires. The variations in mire water chemistry and clastic-influx source area could also control the elemental enrichments in the studied seams. Epiclastic and contemporaneous volcanic inputs into palaeomires seem to control enrichments of Li, B, Sc, and Ti in coal samples, while clastic influx from ophiolitic rocks into palaeomires caused to enrichments of Cr, V and Ni. Furthermore, the liberated Ba, Sr, and As ions from the alteration of epiclastic and contemporaneous volcanic inputs are absorbed by syngenetic zeolite minerals, while anoxic conditions in the palaeomires resulted in precipitation of Sr-barite and As-bearing pyrite grains during peat accumulation and/or early diagenetic stages. Overall, the differences in water chemistry of mire water, epiclastic and contemporaneous volcanic inputs, and clastic influx from the adjacent areas also caused several elemental enrichments and variations in mineralogical compositions of the Middle Miocene coal seams in the Alpu coalfield.

本研究的重点是确定 Alpu 煤田（土耳其中部埃斯基谢希尔）七个煤炭勘探井内煤层（向上，D、C、B、A 和 S0）的矿物学和元素成分。此外，该研究的特殊目标是通过使用具有不同链接方法以及不同相似性度量的凝聚层次聚类算法对元素之间的关系进行比较分析。通常检测到粘土矿物和石英丰富至主要相，而在研究的煤层 C、B、A 和 S0 中检测到天然沸石形成。 SEM-EDX 数据显示，在有机质中观察到了沸石矿物中的斜发沸石，而结晶和非结晶方沸石矿物以及同生自生菱形钾长石仅在一口研究井的煤层 A 中检测到。蒙脱石基质中存在一些微米级矿物，如磷灰石、独居石和钛氧化物，以及蒙脱石中可测量的钛含量，表明泥炭堆积期间，在弱酸性至中性条件下，发生了外碎屑和同期火山输入的蚀变。 。 D 煤层中缺乏天然沸石和碳酸盐矿物可能是弱酸性至中性条件和半封闭水文地质条件的指标。然而，在 C、B、A 和 S0 煤层的前体泥炭堆积过程中，泥浆水的碱度、地下水位和水文地质状况似乎是变化的。反过来，在中性至弱碱性条件和半封闭至封闭水文地质状况下观察到火山输入的变化。因此，形成了同生自生、微米尺寸的斜发沸石。 此外，某些探井中自生菱形钾长石和同生自生方沸石的存在可能表明溶解的Na ⁺ 浓度、碱度和地下水位局部增加。除了矿物的火山成因之外，微米级的副矿物，如铬铁矿、镍黄铁矿和铜铁矿颗粒，可能源自基底中蛇绿岩的碎屑流入古岩。泥沼水化学和碎屑流入源区的变化也可以控制所研究煤层中的元素富集。古岩中的外碎屑和同期火山活动似乎控制了煤样中 Li、B、Sc 和 Ti 的富集，而蛇绿岩中的碎屑流入古岩中则导致了 Cr、V 和 Ni 的富集。此外，从外碎屑和同生火山输入的蚀变中释放出的 Ba、Sr 和 As 离子被同生沸石矿物吸收，而古矿的缺氧条件导致泥炭堆积和沉积过程中 Sr 重晶石和含 As 黄铁矿颗粒的沉淀。 /或早期成岩阶段。总体而言，沼泽水、碎屑和同时期火山输入以及来自邻近地区的碎屑流入的水化学差异也导致了阿尔普煤田中中新世煤层矿物成分的多种元素富集和变化。