The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules
The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules
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DOI：
10.1073/pnas.1614751114
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发表时间：
2017-06-13
影响因子：
11.1
通讯作者：
Rousseau, Denis-Didier
中科院分区：
文献类型：
--
作者：
Moine, Olivier;Antoine, Pierre;Rousseau, Denis-Didier
末次冰期千年时间尺度变暖阶段的特征，被称为interstadials或Dansgaard-Oeschger事件，需要精确的年表来研究古气候记录。在欧洲大陆，这样的年表只适用于几个主要位于地中海地区的末次冰期花粉和罕见的洞穴堆积物档案。再往北，在大陆低地，黄土和古土壤序列的许多高分辨率记录显示出一致的环境响应的stadial间stadial循环。然而，有限的精度和准确度的发光测年方法通常用于黄土沉积物排除古土壤层位与格陵兰间的精确相关性。为了克服这个问题，放射性碳定年协议已被开发到日期从Nussloch（德国）参考黄土序列的方解石颗粒。它的应用产生了一致的放射性碳年代学的所有土壤层之间形成的47和20万年，明确地显示了相关性的每一个格陵兰岛interstadial确定的同位素记录与特定的土壤层。此外，8个额外的小土壤层27.5和21万年之间只与格陵兰岛的灰尘记录略有减少。这种测年方法揭示了黄土古环境对北方气候变化的高度敏感性。黄土沉积速率之间的连接，芬诺斯堪的纳维亚冰盖的动力学，和海平面的变化。因此，放射性碳“生物钟”所带来的年代学上的改进极大地增强了我们对黄土记录的理解，从而更好地了解末次冰期气候变化对欧洲古环境的影响。
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.