Petrographic, geochemical and carbon isotopic determinations were conducted on five samples from four seams within the Late Cretaceous-Paleocene of the Guaduas Formation in Colombia. The individual coal seams are thin, ranging from 0.59 to 1.2 m, and occur over a 157 m interval. The average weighted ash yield is 13.7% (dry basis), although one sample presented values >35%. Vitrinite reflectance increases from 1.33% in the stratigraphically uppermost seam (La Cuarta) to 1.44% in the lower most coal seam (Cisquera), indicating their rank to be medium volatile bituminous.

The studied sequence of the Guaduas Formation represents a peat environment influenced by shifting depositional settings, particularly in relation to the proximity of marine/brackish water environments as indicated by Sr/Ba values, sulfur, pyrite, δ¹³C and the proportion of telinite. A decrease in inertinite indicates that the peat mires were becoming relatively ‘wetter’ stratigraphically upwards. This trend, unlike that of Sr/Ba and telinite, may be driven by climatic shifts rather than only changes in depositional environment.

Both trace and rare earth elements, plus yttrium (REY) are related to the inorganic fraction of the coal. All rare earth elements are depleted relative to average worldwide hard coals (for trace elements) and average upper continental crust (for REY) with the notable exception of Li and Sb for the high ash yield sample (the La Cuarta lower coal seam). The abundance of some REY elements (i.e. Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) may be more influenced by the presence of illite rather than just the quantity of total ash yield. Based on the relationship between SiO₂ and Nb/Y, the provenance of the inorganics changed from a rhyolitic source at the lowest seam (Cisquera) to a dacite source in the middle layer (El Tesoro) to an andesite source in the stratigraphically uppermost seams (La Gemela and La Cuarta).

对来自哥伦比亚 Guaduas 组晚白垩世-古新世四个煤层的五个样品进行了岩石学、地球化学和碳同位素测定。单个煤层很薄，从 0.59 到 1.2 m，分布在 157 m 的间隔内。平均加权灰分产率为 13.7%（干基），尽管一个样本的值 >35%。镜质体反射率从地层最上层煤层 (La Cuarta) 的 1.33% 增加到最下层煤层 (Cisquera) 的 1.44%，表明它们的等级为中等挥发性沥青。

所研究的 Guaduas 组序列代表了受沉积环境变化影响的泥炭环境，特别是与 Sr/Ba 值、硫、黄铁矿、 δ ¹³ C 和 telinite 比例所指示的海洋/微咸水环境的接近程度有关。惰性物质的减少表明泥炭淤泥在地层向上变得相对“湿润”。与 Sr/Ba 和 telinite 不同，这种趋势可能是由气候变化驱动的，而不仅仅是沉积环境的变化。

微量元素和稀土元素以及钇 (REY) 都与煤的无机部分有关。相对于全球平均硬煤（微量元素）和平均上陆地壳（REY）而言，所有稀土元素都已耗尽，除了高灰分样品（La Cuarta 下煤层）的 Li 和 Sb 之外。某些 REY 元素（即 Eu、Gd、Tb、Dy、Y、Ho、Er、Tm、Yb 和 Lu）的丰度可能更多地受伊利石存在的影响，而不仅仅是总灰分产量的数量。基于SiO ₂和Nb/Y的关系，无机物的物源从最下层的流纹岩来源（Cisquera）转变为中层的英安岩来源（El Tesoro），再到地层最上层的安山岩来源。 （La Gemela 和 La Cuarta）。