Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals
Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals
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DOI：
10.1016/j.epsl.2020.116405
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发表时间：
2020-08
影响因子：
5.3
通讯作者：
David J. Wilson;T. Struve;T. van de Flierdt;Tianyu Chen;Tao Li;A. Burke;L. Robinson
中科院分区：
文献类型：
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作者：
David J. Wilson;T. Struve;T. van de Flierdt;Tianyu Chen;Tao Li;A. Burke;L. Robinson
从末次盛冰期到全新世的深海环流变化序列为理解冰消期气候变化和深海在全球碳循环中的作用提供了重要的见解。虽然人们知道，大量的碳被封存在一个深翻转细胞在冰期和冰川消退期间释放，这些变化的驱动机制仍然没有解决。最近有人提出，南大洋海冰在确定全球深海分层和环流以及碳储存方面发挥着关键作用，但要检验这种概念和模型研究，就需要限制过去环流变化的数据。为此，我们提出了第一个冰消期数据集的钕（Nd）同位素测量的绝对日期的深海珊瑚从现代较低的绕极深水深度在德雷克海峡。我们的记录表明，在末次盛冰期期间，2.5 ε Nd单位的冰消变化，放射成因值高达ε Nd=-5.9，为分层冰川循环模式提供了证据，该模式限制了来自北大西洋深水的Nd在低细胞中的掺入。在冰消期，一个新的大西洋的影响，在深南大洋早在海因里希体育场1记录，与南极海冰退缩，其次是一个简短的返回到更太平洋的价值观在南极寒冷的Reasons。这些变化表明南大洋过程在设置深海环流方面的强烈影响，并支持建议的海冰对深海结构的控制。此外，通过限制在南大洋较低的绕极深水的Nd同位素组成，我们的新数据是重要的，解释在其他海洋盆地的冰消环流变化，并支持空间异步返回北大西洋深层东南和西南大西洋。
The sequence of deep ocean circulation changes between the Last Glacial Maximum and the Holocene provides important insights for understanding deglacial climate change and the role of the deep ocean in the global carbon cycle. Although it is known that significant amounts of carbon were sequestered in a deep overturning cell during glacial periods and released during deglaciation, the driving mechanisms for these changes remain unresolved. Southern Ocean sea-ice has recently been proposed to play a critical role in setting the global deep ocean stratification and circulation, and hence carbon storage, but testing such conceptual and modelling studies requires data constraining past circulation changes. To this end, we present the first deglacial dataset of neodymium (Nd) isotopes measured on absolute-dated deep-sea corals from modern Lower Circumpolar Deep Water depths in the Drake Passage. Our record demonstrates deglacial variability of 2.5 ε Nd units, with radiogenic values of up to ε Nd=− 5.9 during the Last Glacial Maximum providing evidence for a stratified glacial circulation mode with restricted incorporation of Nd from North Atlantic Deep Water in the lower cell. During the deglaciation, a renewed Atlantic influence in the deep Southern Ocean is recorded early in Heinrich Stadial 1, coincident with Antarctic sea-ice retreat, and is followed by a brief return to more Pacific-like values during the Antarctic Cold Reversal. These changes demonstrate a strong influence of Southern Ocean processes in setting deep ocean circulation and support the proposed sea-ice control on deep ocean structure. Furthermore, by constraining the Nd isotopic composition of Lower Circumpolar Deep Water in the Southern Ocean, our new data are important for interpreting deglacial circulation changes in other ocean basins and support a spatially asynchronous return of North Atlantic Deep Water to the deep southeast and southwest Atlantic Ocean.