Elemental, biomarker, palynology and maceral data from Seam 1, Schöningen and associated interbeds

Sphagnum moss is the dominant plant type in modern boreal and (sub)arctic ombrotrophic bogs and is of particular interest due to its sensitivity to climate and its important role in wetland biogeochemistry. Here we reconstruct the occurrence of Sphagnum moss - and associated biogeochemical change - within a thermally immature, early Paleogene (~55 Ma) lignite from Schöningen, NW Germany using a high-resolution, multi-proxy approach. Changes in the abundance of Sphagnum-type spores and the C23/C31n-alkane ratio indicate the expansion of Sphagnum moss within the top of the lignite seam. This Sphagnum moss expansion is associated with the development of waterlogged conditions, analogous to what has been observed within modern ombrotrophic bogs. The similarity between biomarkers and palynology also indicates that the C23/C31n-alkane ratio may be a reliable chemotaxonomic indicator for Sphagnum during the early Paleogene. The d13C value of bacterial hopanes and mid-chain n-alkanes indicates that a rise in water table is not associated with a substantial increase in aerobic methanotrophy. The absence of very low d13C values within the top of the seam could reflect either less methanogenesis or less efficient methane oxidation under waterlogged sulphate-rich conditions.

泥炭藓（Sphagnum moss）是现代北方寒带及（亚）北极贫营养沼泽（ombrotrophic bogs）中的优势植物类群，因其对气候变化的敏感性以及在湿地生物地球化学循环中的关键作用而受到学界广泛关注。本研究以德国西北部舍宁根地区一处热未成熟的古近纪早期（约55 Ma）褐煤序列为研究对象，采用高分辨率多代用指标方法，重建了泥炭藓的出现历史及与之相关的生物地球化学变化。泥炭藓型孢子丰度与C23/C31正构烷烃比值的变化表明，褐煤煤层顶部的泥炭藓类群发生了显著扩张。该泥炭藓扩张事件与积水环境的发育密切相关，这与现代贫营养沼泽中观测到的生态过程高度相似。生物标志物与孢粉学分析结果的一致性还证实，C23/C31正构烷烃比值可作为古近纪早期泥炭藓的可靠化学分类学指标。细菌藿烷类化合物与中链正构烷烃的碳同位素（δ13C）值显示，研究区地下水位上升并未伴随有氧甲烷氧化作用的显著增强。煤层顶部未出现极低的δ13C值，这一现象可能反映了两种情况：一是富硫酸盐积水环境下甲烷生成量较低，二是该环境下甲烷氧化效率不足。