Radiocarbon dating of Loess-Palaeosol-Sequences from Remagen-Schwalbenberg using Earthworm Calcite Granules

在dfg资助的terraclime项目框架内，来自Remagen（德国中莱茵河谷）附近Schwalbenberg的已调查黄土-古溶土层序列（LPS）的精确测年是主要挑战之一。施瓦尔本贝格是独一无二的，因为它保存了中欧西部末次冰期气候变化的完整陆地记录，特别是海洋同位素阶段（MIS） 3。在记录和解释千年尺度的变暖时期的背景下，被称为格陵兰间冰期（GI）或Dansgaard-Oeschger事件，以及它们对景观形成的影响，定年方法尤为重要。间期在所研究的层序中表现为不同发育程度的土壤层，可以使用为terraclime项目精心设计的多代理方法精确追踪。相比之下，确切的年代地层位置仍然不确定，特别是由于不利的矿物学特征和相对较大的发光年龄误差范围，部分超过了间冰期的持续时间。在这种背景下，最近开发了一种有希望的测年方法，应用化石蚯蚓方解石颗粒（ECG）的放射性碳测年，在Nussloch类型剖面和法国西北部显示了非常有希望的结果（Moine等人，2017;Prud 'homme等人，2019）。这种新方法更为重要，因为传统的14c测年残留物在LPS中很少，阻碍了可靠的放射性碳年表的发展。在我们的准备研究中，在Schwalbenberg准备了一个新的剖面，并以高分辨率（5厘米间隔，共105个样品）进行了采样。该剖面的特征是几种棕壤、冻土带和MIS 3年龄的黄土沉积，在古土壤中显示出特别高的ECG数量。首先，放射性碳年龄显著改善了Schwalbenberg LPS的年龄模型，并表明样品适合于14c定年。因此，本补充建议的主要目标是对来自施瓦尔本贝格剖面的另外40个样品进行放射性碳定年。这些数据将被整合到terraclime项目正在进行的工作中，并有助于验证发光年龄和改进OSL协议。最近，对新剖面的所有样品进行了δ18O和δ13C同位素分析。基于这些分析和互补的ECG测年方法，将有可能在可靠的年代地层学背景下解释基本的古气候数据，并将它们与区域和全球古气候档案进行比较。

In the frame of the DFG-funded TERRACLIME-project, precise dating of investigated Loess-Palaeosol-Sequences (LPS) from the Schwalbenberg near Remagen (Middle Rhine valley, Germany) is one of the major challenges. The Schwalbenberg is unique because it preserves a complete terrestrial record of Last Glacial climate variability in western Central Europe, and especially of Marine Isotope Stage (MIS) 3. In context to the documentation and interpretation of millennial-timescale warming periods, named Greenland Interstadials (GI) or Dansgaard-Oeschger events, and their impact on landscape formation the dating approach gains particular importance. The interstadial periods appear as soil horizons of different development degrees within the investigated sequences and can be traced precisely using the multi-proxy-approach elaborated for the TERRACLIME-project. In contrast, the exact chronostratigraphic position remains uncertain, especially due to unfavourable mineralogical characteristics and relatively large error ranges of luminescence ages, which partly exceed the duration of interstadial periods. In this context, a promising dating approach has recently been developed applying radiocarbon dating of fossil Earthworm Calcite Granules (ECG) that shows very promising results for the Nussloch type section and northwestern France (Moine et al., 2017; Prud’homme et al., 2019). This new approach is even more important as conventional 14C-datable remains are scarce in LPS hampering the development of robust radiocarbon chronologies. Within our preparatory studies, a new profile at the Schwalbenberg was prepared and sampled in high resolution (5 cm intervals, 105 samples in total). The profile is characterised by several brown soils, tundra gleys and loess deposits of MIS 3 age, showing particularly high numbers of ECG in palaeosols. First radiocarbon ages significantly improved the age model for the Schwalbenberg LPS and shows that the sampled material is suitable for 14C-dating. Thus, the main objective of this supplementary proposal is radiocarbon dating of additional 40 samples from the Schwalbenberg profile. The data will be integrated into the ongoing work of the TERRACLIME-project and help to validate luminescence ages and refine OSL protocols. Recently, isotope analyses (δ18O und δ13C) have already been conducted on all samples from the new profile. Based on these analyses and the complementary ECG dating approach, it will be possible to interpret essential palaeoclimate data against the background of a robust chronostratigraphy and to compare them to regional and global palaeoclimate archives.