The present study focuses on the inorganic geochemical features of the bituminous coal samples from the Raniganj and the Jharia Basins, as well as the anthracite samples from the Himalayan fold-thrust belts of Sikkim, India. The SiO₂ content (48.05 wt% to 65.09 wt% and 35.92 wt% to 50.11 wt% in the bituminous and anthracite samples, respectively) and the ratio of Al₂O₃/TiO₂ (6.97 to 17.03 in the bituminous coal samples and 10.34 to 20.07 in the anthracite samples) reveal the intermediate igneous source rock composition of the minerals. The ratio of the K₂O/Al₂O₃ in the ash yield of the bituminous coal samples (0.03 to 0.09) may suggest the presence of kaolinite mixed with montmorillonite, while its range in the ash yield of the anthracite samples (0.16 to 0.27) may imply the presence of illite mixed with kaolinite. The chemical index of alteration values may suggest the moderate to strong chemical weathering of the source rock under sub-humid to humid climatic conditions. The plot of the bituminous coal samples in the A–CN–K diagram depicts the traditional weathering trend of parent rocks, but the anthracite samples plot near the illite field and are a bit offset from the weathering trend. This may imply the plausible influences of the potassium-metasomatism at post coalification stages, which is further supported by high K₂O/Na₂O ratio (29.88–80.13). The Fourier transform infrared spectra further reveal the hydroxyl stretching intensity of illite in the anthracite samples substantiating the effect of the epigenetic potassium-metasomatism. The decrease in total kaolinite intensity/compound intensity of quartz and feldspar may provide additional evidence towards this epigenetic event.

本研究的重点是来自 Raniganj 和 Jharia 盆地的烟煤样品以及来自印度锡金喜马拉雅褶皱冲断带的无烟煤样品的无机地球化学特征。SiO ₂含量（分别在烟煤和无烟煤样品中为 48.05 wt% 到 65.09 wt% 和 35.92 wt% 到 50.11 wt%）和 Al ₂ O ₃ /TiO ₂比（在烟煤样品中为 6.97 到 17.03 和无烟煤样品中的 10.34 至 20.07）揭示了矿物的中间火成岩源岩组成。K ₂ O/Al ₂ O _3之比烟煤样品的灰分含量（0.03 至 0.09）可能表明存在与蒙脱石混合的高岭石，而无烟煤样品的灰分含量范围（0.16 至 0.27）可能表明存在与高岭石混合的伊利石。蚀变值的化学指数可能表明烃源岩在亚湿润至湿润气候条件下的中度至强化学风化。A-CN-K图中烟煤样品的图描绘了母岩的传统风化趋势，但无烟煤样品绘制在伊利石附近，与风化趋势略有偏移。这可能暗示了钾交代作用在煤化后阶段的合理影响，这进一步得到了高 K ₂ O/Na _{2的支持。}O 比率（29.88–80.13）。傅里叶变换红外光谱进一步揭示了无烟煤样品中伊利石的羟基拉伸强度，证实了表观成因钾交代作用的影响。石英和长石的总高岭石强度/化合物强度的降低可能为这一表观成因事件提供额外的证据。