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

在DFG资助的TERRACLIME项目的框架内，对德国雷马根附近施瓦本贝格(德国莱茵河中谷)调查的黄土-古土壤序列(LPS)的精确测年是主要挑战之一。Schwalbenberg的独特之处在于它保存了西欧最后一次冰川气候变化的完整陆地记录，特别是海洋同位素阶段3。在记录和解释千年时间尺度的变暖时期，即格陵兰间期(GI)或丹斯加德-奥施格事件及其对景观形成的影响方面，测年方法具有特别重要的意义。在所调查的层序中，间歇期表现为不同发育程度的土壤层，并可以使用为TERRACLIME项目精心设计的多代理方法进行精确追踪。相比之下，准确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，这部分超过了星际时期的持续时间。在这方面，最近开发了一种很有希望的测年方法，对化石蚯蚓方解石颗粒进行放射性碳测年，显示了Nussloch类型剖面和法国西北部非常有希望的结果(Moine等人，2017年；Prud‘homme等人，2019年)。这种新的方法甚至更加重要，因为在脂多糖中传统的14C可测年遗骸很少，这阻碍了可靠的放射性碳年代学的发展。在我们的前期研究中，在Schwalbenberg准备了一份新的剖面图，并以高分辨率(间隔5厘米，总共105个样本)进行了取样。该剖面以几种棕壤、冻土潜育体和MIS3年代的黄土沉积为特征，在古土壤中表现出特别高的心电信号。首先，~(14)C测年显着改进了Schwalbenberg LPS的年龄模式，表明样品适合于~(14)C测年。因此，这项补充提案的主要目标是对施瓦本贝格剖面的另外40个样品进行放射性碳测年。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完善OSL协议。最近，已经对新剖面的所有样品进行了同位素分析(δ18O和δ13C)。基于这些分析和互补的心电测年方法，将有可能在稳健的年代地层学的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.