This study focuses on ascertaining controlling factors and differences on mineralogical and elemental contents for reconstructing palaeoenvironmental conditions of both seams applying standard coal characteristics, mineralogical, coal-petrologic, and elemental data of the Orhaneli coalfield. The studied coalfield, one of the important coalfields in NW Turkey, includes two workable coal seams, the lower with 0.5–2 m and the upper with 5–6 m in thickness, which are separated by 2–5 m thick, grayish-green limnic claystone. The floor rocks of the both seams are limnic claystones, whereas the roof rock of the upper seam is the tuffite layers-bearing lacustrine marls. Matrix and xylite-rich lithotypes are common in the upper seam, while alternations of xylite-clayey bands (detro-xylite and xylo-detritic) are common in the lower seam. The lower seam is also characterized with the presence of altered tuff layers, while freshwater gastropod shell-bearing bands were identified from the upper seam. Even though the banding character and maceral composition of the coals were invariant between the seams, there are distinct differences in mineralogy and elemental composition, that can be related to the nature of the clastic sediment influx and contemporary volcanic inputs into freshwater forested mires.

The lower seam is characterized by high ash yields (%44.2–64.3, d) and relatively high concentrations of aluminosilicate-affiliated elements and REY (rare earth elements and Y). In contrast, the upper seam has relatively low ash yield, and is slightly enriched B concentration. The B enrichment in the upper seam is presumably controlled by the presence of clay mineral (e.g., illite) and clastic volcanogenic accessory minerals (e.g., apatite). Arsenic is the only enriched element in both seams due to development of anoxic conditions. Although no traceable As was detected from syngenetic framboidal pyrite grains, the contemporary volcanic inputs (e.g., air-fall ash/tephra) along with leached surface waters into palaeomires might be source for As, while the development of anoxic conditions palaeomires could cause formation of syngenetic pyrite grains. Thus, the As concentrations of the studied samples are elevated. Nevertheless, the difference on ash yields and mineralogical compositions between studied seams might be related with different clastic influx ratios and contemporary volcanic inputs, in turn, aluminosilicate affiliated elements display different concentration coefficients (CC) values in the studied seams, and high B concentrations that are not expectable for a limnic coal Besides, enrichment of Cr, V and Ni in the upper seam are controlled by clastic V-bearing chromite grains from Orhaneli chromite deposit in the adjacent area. Furthermore, the contemporary volcanic inputs into the palaeomire of the lower seam, and their alteration under anoxic conditions caused REY enrichment and the formation of kaolinite and smectite matrices of clay aggregates in coal and altered tuff layers in this seam.

本研究的重点是确定控制因素和矿物和元素含量的差异，以应用Orhaneli煤田的标准煤特征，矿物学，煤岩学和元素数据重建两个煤层的古环境条件。所研究煤田是土耳其西北部重要煤田之一，包括2个可开采煤层，下部0.5-2 m，上部5-6 m，相隔2-5 m，灰绿色石灰质粘土岩。两层煤层底板岩为石灰质粘土岩，上部煤层顶岩为凝灰岩层—湖相泥灰岩。上层煤层常见基质和富含木料石的岩型，而下层煤层常见木石-粘土带（detro-xylite 和 xylo-detritic）交替。下层接缝的特征还在于存在改变的凝灰岩层，而从上层接缝处发现了淡水腹足类带壳带。尽管煤层之间的带状特征和煤质组成是不变的，但矿物学和元素组成存在明显差异，这可能与碎屑沉积物流入的性质和当代火山输入淡水森林沼泽有关。

下层煤层的特点是灰分产量高 (%44.2–64.3, d) 和相对高浓度的铝硅酸盐附属元素和 REY（稀土元素和 Y）。相比之下，上层煤层出灰量相对较低，B 浓度略高。上层煤层中的 B 富集可能受粘土矿物（例如伊利石）和碎屑火山成因副矿物（例如磷灰石）的控制。由于缺氧条件的发展，砷是两个接缝中唯一富含的元素。尽管从同生的枝状黄铁矿颗粒中未检测到可追踪的砷，但当代火山输入（例如，空气坠落灰/火山灰）以及浸出到古珊瑚的地表水可能是砷的来源，而缺氧条件的发展可能导致古珊瑚的形成同生黄铁矿颗粒。因此，所研究样品的 As 浓度升高。然而，研究煤层之间灰分产量和矿物组成的差异可能与不同的碎屑流入率和当代火山输入有关，反过来，铝硅酸盐附属元素在研究煤层中显示不同的浓度系数（CC）值，以及高 B 浓度，此外，上层煤层 Cr、V 和 Ni 的富集受邻近地区 Orhaneli 铬铁矿床的含碎屑 V 铬铁矿颗粒控制。此外，当代火山输入到下层煤层的古陆，