Laboratoire de Géographie Physique, Environnements Quaternaires et Actuels, Centre National de la Recherche Scientifique (CNRS)/Université Paris 1 Panthéon-Sorbonne/Université Paris-Est-Créteil-Val-de-Marne (UPEC), 92195 Meudon, France;
Laboratoire de Géographie Physique, Environnements Quaternaires et Actuels, Centre National de la Recherche Scientifique (CNRS)/Université Paris 1 Panthéon-Sorbonne/Université Paris-Est-Créteil-Val-de-Marne (UPEC), 92195 Meudon, France.
Proc Natl Acad Sci U S A. 2017 Jun 13;114(24):6209-6214. doi: 10.1073/pnas.1614751114. Epub 2017 May 30.
The characterization of Last Glacial millennial-timescale warming phases, known as interstadials or Dansgaard-Oeschger events, requires precise chronologies for the study of paleoclimate records. On the European continent, such chronologies are only available for several Last Glacial pollen and rare speleothem archives principally located in the Mediterranean domain. Farther north, in continental lowlands, numerous high-resolution records of loess and paleosols sequences show a consistent environmental response to stadial-interstadial cycles. However, the limited precision and accuracy of luminescence dating methods commonly used in loess deposits preclude exact correlations of paleosol horizons with Greenland interstadials. To overcome this problem, a radiocarbon dating protocol has been developed to date earthworm calcite granules from the reference loess sequence of Nussloch (Germany). Its application yields a consistent radiocarbon chronology of all soil horizons formed between 47 and 20 ka and unambiguously shows the correlation of every Greenland interstadial identified in isotope records with specific soil horizons. Furthermore, eight additional minor soil horizons dated between 27.5 and 21 ka only correlate with minor decreases in Greenland dust records. This dating strategy reveals the high sensitivity of loess paleoenvironments to Northern Hemisphere climate changes. A connection between loess sedimentation rate, Fennoscandian ice sheet dynamics, and sea level changes is proposed. The chronological improvements enabled by the radiocarbon "earthworm clock" thus strongly enhance our understanding of loess records to a better perception of the impact of Last Glacial climate changes on European paleoenvironments.
末次冰期千年尺度变暖阶段的特征，被称为间冰段或丹斯加德-奥舍格事件，需要精确的年代学来研究古气候记录。在欧洲大陆，只有几个末次冰期花粉和罕见洞穴石笋档案有这样的年代学，主要分布在地中海地区。在更北的大陆低地，大量高分辨率的黄土和古土壤序列记录显示出与冰期-间冰期循环一致的环境响应。然而，在黄土沉积物中常用的发光测年方法的精度和准确性有限，排除了古土壤层与格陵兰间冰段的确切关联。为了克服这个问题，开发了一种放射性碳测年方案，用于对来自德国努斯罗赫（Nussloch）参考黄土序列的蚯蚓方解石颗粒进行测年。它的应用产生了所有在 47 到 20 千年前形成的土壤层的一致放射性碳年代学，并明确显示了在同位素记录中识别出的每一个格陵兰间冰段与特定土壤层的相关性。此外，在 27.5 到 21 千年前确定的另外 8 个次要土壤层仅与格陵兰尘埃记录的轻微减少相关。这种测年策略揭示了黄土古环境对北半球气候变化的高度敏感性。提出了黄土沉积速率、芬诺斯堪的亚冰盖动力学和海平面变化之间的联系。放射性碳“蚯蚓钟”带来的年代学改进极大地增强了我们对黄土记录的理解，使我们更好地认识到末次冰期气候变化对欧洲古环境的影响。
