Abstract This study focuses on variations in petrographic composition and chemistry of macerals from different coalfields in Colombia. The coal-bearing formations in Colombia occur in the age interval from the Maastrichtian in the Upper Cretaceous to the Paleogene and Neogene (Paleocene, Eocene, Oligocene, and Late Pliocene) up to Early Pleistocene. The coals range in rank from lignite to semianthracite. Petrographically, the coal is composed dominantly of macerals of the vitrinite group (>50% by volume). The coals from the regions of Antioquia, Cordoba, and Caldas are characterized by relatively high proportions of liptinite (up to 30 vol%). The inertinite contents vary up to 30 vol%, and the coals from the regions of Boyaca and Guajira contain the highest quantities of this maceral group. The Colombian coals studied have low moisture, except for the coal from Caldas being lignite type A. The sulfur content ranges between 0.28 weigh % in coal from Guajira to slightly above 2% in coal from Cordoba and Cauca. The coal facies diagrams suggest that palaeomires developed mostly under limno-telmatic to wet forest mire conditions. The ratios of microlithotypes suggest that the original peat mires evolved under fluvial, upper deltaic and brackish settings. Overall coal petrography data suggest that peat-forming vegetation and water tables in palaeomires experienced significant variations between the Upper Maastrichtian to Pliocene - Early Pleistocene period. Variations in chemistry of coal macerals reflect to large extent the coal rank variations. Specifically, with the increase in vitrinite reflectance (Ro), the contents of aliphatic functional groups decrease whereas those of the aromatic groups increase. The values of CH2/CH3 ratios also decrease with increasing coal rank (2.24 in Boyaca and 0.97 in Cauca). Expectedly, spectral differences between individual macerals are most distinct in the low rank coals (0.48% Ro).

中文翻译：

---

哥伦比亚煤的岩石学特征、化学变化和古环境解释

摘要 本研究的重点是来自哥伦比亚不同煤田的岩相成分和化学成分的变化。哥伦比亚的含煤地层出现在上白垩统的马斯特里赫特到古近纪和新近纪（古新世、始新世、渐新世和晚上新世）到早更新世的时代区间。煤的等级范围从褐煤到半无烟煤。在岩相学上，煤主要由镜质组的微晶组成（>50% 体积）。安蒂奥基亚、科尔多瓦和卡尔达斯地区的煤具有相对较高比例的 liptinite（高达 30 vol%）。惰性物质的含量高达 30 vol%，来自 Boyaca 和 Guajira 地区的煤中含有最多的这种微晶组。研究的哥伦比亚煤含水量低，除了来自 Caldas 的煤是 A 型褐煤。 硫含量在 Guajira 煤的 0.28% 到 Cordoba 和 Cauca 煤的略高于 2% 之间。煤相图表明古盐沼主要是在湖沼-telmatic 到潮湿的森林泥沼条件下发育的。微岩型的比率表明原始泥炭沼泽是在河流、上三角洲和半咸水环境下演化的。总体煤岩学数据表明，在上马斯特里赫特至上新世-早更新世期间，古珊瑚中的泥炭形成植被和地下水位经历了显着变化。煤质化学变化在很大程度上反映了煤级的变化。具体而言，随着镜质体反射率（Ro）的增加，脂肪族官能团的含量减少，而芳香族官能团的含量增加。CH2/CH3 比值也随着煤等级的增加而降低（博亚卡为 2.24，考卡为 0.97）。可以预期，在低阶煤 (0.48% Ro) 中，单个煤体之间的光谱差异最为明显。