High-resolution geochemical record of environmental changes during MIS 3 from the northern Alps (Nesseltalgraben, Germany)
High-resolution geochemical record of environmental changes during MIS 3 from the northern Alps (Nesseltalgraben, Germany)
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DOI：
10.1016/j.quascirev.2019.06.013
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发表时间：
2019-08
影响因子：
4
通讯作者：
C. Mayr;P. Stojakowits;B. Lempe;M. Blaauw;Volker Diersche;Madleen Grohganz;M. L. Correa;C. Ohlendorf;P. Reimer;B. Zolitschka
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文献类型：
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作者：
C. Mayr;P. Stojakowits;B. Lempe;M. Blaauw;Volker Diersche;Madleen Grohganz;M. L. Correa;C. Ohlendorf;P. Reimer;B. Zolitschka
最近在德国东南部发现的内塞尔塔尔格拉本遗址的峡谷斜坡为北方石灰质阿尔卑斯山提供了独特的末次冰期沉积物记录。21米长的剖面主要由细粒湖相-沼泽相沉积物组成，上覆有几米长的冰川冲积砾石和末次冰盛期的沉积冰碛，下覆有杂岩。年龄模型包括29个放射性碳分析和一个古地磁异常（Laschamp事件），共同提供了一个模拟的年龄范围从c。59 - 29.6 ka cal BP，即海洋同位素阶段（MIS）3。除了描述岩相外，X射线荧光扫描和元素分析还提供了地球化学成分的高分辨率记录。XRF数据的多变量分析将Ca与其他主要元素分开。碳酸盐含量以Ca和总无机碳为代表，在反复出现的钙质粉砂到桑迪层中达到最大值，并与冰川成因有关。这些表明重复的内高山局部冰川在stadials的MIS 3。扫描电子显微镜和XRF数据证实了这些层的碎屑起源。与此相反，有机质和元素更耐化学风化（硅，钛，锆）积累在interstadials和同时升高Rb/Sr比值表明风化加剧。Nesseltalgraben确定的高频代理变化反映了与格陵兰冰芯和阿尔卑斯山洞穴沉积物的氧同位素记录相当的stadial stadial气候变率。因此，Nesseltalgraben是欧洲大陆覆盖整个MIS 3的极少数独立定年沉积物记录之一，反映了完整的Dansgaard-Oeschger气候变化。
Ravine slopes at the recently discovered Nesseltalgraben site in southeastern Germany provide a unique last glacial sediment record for the Northern Calcareous Alps. The 21 m-long profile is dominated by fine-grained lacustrine-palustrine sediments overlain by several metres of glacifluvial gravels and lodgement tills of the Last Glacial Maximum and underlain by a diamicton. The age model includes 29 radiocarbon analyses and one paleomagnetic anomaly (Laschamp event) together providing a modelled age range fromc. 59 to 29.6 ka cal BP, i.e. Marine Isotope Stage (MIS) 3. Apart from a description of the lithofacies, X-ray-fluorescence (XRF) scanning and elemental analyses provide high-resolution records of the geochemical composition. Multivariate analyses of XRF data separate Ca from other major elements. Carbonate contents, represented by Ca and total inorganic carbon, reach maxima in repeatedly occurring calcareous silty to sandy layers and are related to glacigenic origin. These indicate repeated inner-alpine local glaciations during stadials of MIS 3. Scanning electron microscopy and XRF data confirm the detrital origin of these layers. In contrast, organic matter and elements more resistant to chemical weathering (Si, Ti, Zr) accumulated during interstadials and concurrently elevated Rb/Sr ratios indicate intensified weathering. The high-frequency proxy variations determined for Nesseltalgraben reflect interstadial-stadial climate variability comparable with oxygen-isotope records from Greenland ice cores and Alpine speleothems. Thus, Nesseltalgraben is among the very few independently dated sediment records from continental Europe covering the entire MIS 3 and reflecting the full Dansgaard-Oeschger climate variability.