Abstract. Situated at the southern edge of the proto-North Sea the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data of bulk organic matter (δ¹³C_TOC), organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation embedded into a new robust age model. This is based on eustatic sea-level changes, biostratigraphy, and a correlation to existing radiometric ages. Based on the δ¹³C_TOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ¹³C_TOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ¹³C_TOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least 4 minor CIEs with a maximum negative shift of −1.3 ‰ in δ¹³C_TOC in the upper part of the studied section are characteristic for the EECO. Palynological analysis across the Main Seam proved that shifts in δ¹³C_TOC values are correlated with changes in the peat forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to an angiosperm dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ¹³C_TOC values shortly after the onset of the CIE, which is here recognized as a common feature of terrestrial and marginal marine PETM-records worldwide and may be related to changes in the vegetation including different carbon isotope budgets of gymnosperms and angiosperms.

中文翻译：

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原始北海南部边缘褐煤层序中的早始新世碳同位素漂移（德国舍宁根）

摘要。德国下萨克森州 Helmstedt 褐煤矿区的始新世 Schöningen 组位于原始北海的南部边缘，其特征是几个褐煤煤层与河口至半咸水互层交替。在这里，我们展示了嵌入到新的鲁棒年龄模型中的 98 m 厚的 Schöningen 组序列的散装有机质 (δ ¹³ C _TOC )、有机碳含量 (%TOC) 和孢粉形态的碳同位素数据。这是基于海平面变化、生物地层以及与现有辐射年龄的相关性。基于 δ ¹³ C _TOC我们观察到六个负碳同位素偏移 (CIE) 的数据，反映了大规模的短期碳循环扰动。在主煤层和随后的海相夹层中，δ ¹³ C _TOC值的强 CIE 为 -2.6 ‰，这可能与古新世-始新世热最大值（PETM）有关。随后的 CIE 在 δ ¹³ C _TOC值中为 -1.7 ‰，可能与始新世热最大值 2 (ETM2) 或 ETM2 之前稍早的事件相关。包括至少 4 个次要 CIE 在内的高幅度气候波动，其中研究剖面上部的δ ¹³ C _TOC的最大负移为 -1.3 ‰，是 EECO 的特征。整个主接缝的孢粉学分析证明 δ 的变化¹³ C _TOC值与形成泥炭的湿地植被的变化相关，特别是在 PETM 开始时，从混合被子植物和裸子植物群变为以被子植物为主的植被。在 CIE开始后不久，与 PETM 相关的 CIE 显示出明显的回升至更高的 δ ¹³ C _TOC值，这里被认为是全球陆地和边缘海洋 PETM 记录的共同特征，可能与植被的变化有关包括裸子植物和被子植物的不同碳同位素预算。