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

使用蚯蚓方解石颗粒对雷马根-施瓦尔本贝格黄土-古土壤序列进行放射性碳测年

• 批准号: 439443769
• 负责人: Dr. Peter Fischer
• 金额: --
• 依托单位: Lehrstuhl für Geomorphologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/439443769?language=en
• 关键词: Radiocarbon; dating; Loess; Palaeosol; Sequences

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.

在DFG资助的TERRACLIME项目的框架内，对雷马根（莱茵河河谷中部，德国）附近的施瓦尔本贝格黄土-古土壤-序列（LPS）进行精确测年是主要挑战之一。施瓦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。在记录和解释千年时间尺度的变暖时期，称为格陵兰岛Interstadials（GI）或Dansgaard-Oeschger事件及其对景观形成的影响的背景下，测年方法变得特别重要。在所调查的序列中，不同发育程度的土壤层位出现了间歇期，并且可以使用为TERRACLIME项目制定的多代理方法精确追踪。与此相反，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发光年龄的误差范围相对较大，部分超过了间歇期的持续时间。在这种情况下，最近开发了一种有希望的定年方法，该方法应用蚯蚓化石方解石颗粒（ECG）的放射性碳定年，该方法在Nussloch型剖面和法国西北部显示出非常有希望的结果（Moine等人，2017; Prud'homme等人，2019年）。这种新的方法是更重要的，因为传统的14 C-测年仍然是稀缺的LPS阻碍了强大的放射性碳年表的发展。在我们的预备性研究中，在施瓦本贝格制作了一个新的剖面图，并以高分辨率进行了采样（间隔5厘米，共105个样本）。该剖面的特点是几个棕色土壤，冻原潜育沟和MIS 3年龄的黄土沉积，表现出特别高的古土壤中的心电图。第一放射性碳年龄显着提高了年龄模型的Schwalbenberg LPS和样品的材料是适合14 C-定年。因此，本补充提案的主要目标是对施瓦本贝格剖面的另外40个样本进行放射性碳测年。这些数据将被纳入正在进行的TERRACLIME项目的工作，并有助于验证发光年龄和完善OSL协议。最近，已对新剖面的所有样品进行了同位素分析（δ 18 O和δ 13 C）。根据这些分析和补充心电图测年方法，将有可能解释一个强大的年代地层学背景下的基本古气候数据，并将它们与区域和全球古气候档案进行比较。