Evidence from the Northeastern Atlantic basin for variability in the rate of the meridional overturning circulation through the last deglaciation
Evidence from the Northeastern Atlantic basin for variability in the rate of the meridional overturning circulation through the last deglaciation
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DOI：
10.1016/j.epsl.2005.09.061
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发表时间：
2005-12-15
影响因子：
5.3
通讯作者：
Cortijo, E
中科院分区：
文献类型：
--
作者：
Gherardi, JM;Labeyrie, L;Cortijo, E
来自亚热带西大西洋的第一项研究，使用Pa-231/Th-230比值作为深水环流的运动学代理，提供了令人信服的证据，表明气候与末次冰消期经向翻转环流（MOC）速率之间存在密切联系。然而，这些结果值得确认从额外的位置和水的深度，因为沉积Pa-231/Th-230的比例在循环活力方面的解释可能会受到偏差的颗粒通量和成分的变化。我们已经测量了Pa-231/Th-230的核心从伊比利亚边缘，在东北大西洋盆地，并将这些新的结果从西大西洋盆地的数据进行了比较。我们发现，在H1和YD和随后的增加，首先认识到沉积在本努达隆起的沉积物中的循环减少也很明显，在东部盆地，在一个完全不同的沉积制度，证实沉积Pa-231/Th-230比记录全盆地的变化，在深水循环。然而，东部和西部的记录之间的一些差异也得到了承认，提供了初步的证据来区分更新率在两个北大西洋盆地和浅，深翻转。我们的研究结果表明，可能存在两个来源的冰川北大西洋中层深水（GNAIW），一个在拉布拉多海南部和另一个西部的罗卡尔高原。这两个来源都有助于北半球的翻转，但这两个有不同的敏感性，从Laurentide和Fermoscandian冰盖在冰消期的融水。这些结果表明，通过对比大西洋不同区域沉积物Pa-231/Th-230的演变，可以获得关于大西洋深部通风的几何形状和强度的更多信息。(C)2005 Elsevier B. V.保留所有权利。
A first study from the subtropical western Atlantic, using Pa-231/Th-230 ratios as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of Meridional Overturning Circulation (MOC) over the last deglaciation. However, these results warrant confirmation from additional locations and water depths because the interpretation of the sedimentary Pa-231/Th-230 ratio in terms of circulation vigor can be biased by variations in particle flux and composition. We have measured Pa-231/Th-230 in a core from the Iberian margin, in the Northeastern Atlantic basin, and have compared these new results to the data from the western Atlantic basin. We find that the reduction in the circulation during H1 and YD and the subsequent increases first recognized in the sediment deposited on Ben-nuda Rise are also evident in the eastern basin, in a totally different sedimentary regime, confirming that sedimentary Pa-231/Th-230 ratios record basin-wide changes in deep water circulation. However, some differences between the eastern and western records are also recognized, providing preliminary evidence to differentiate between renewal rates in the two North Atlantic basins and between shallower and deeper overturning. Our results suggest the possible existence of two sources of Glacial North Atlantic Intermediate Deep Water (GNAIW), one in the south Labrador Sea and another west of Rockall Plateau. Both sources contributed to the meridional overturning but the two had different sensitivity to meltwater from the Laurentide and the Fermoscandian ice sheets during the deglaciation. These results indicate that additional information on the geometry and strength of the ventilation of the deep Atlantic can be obtained by contrasting the evolution of sediment Pa-231/Th-230 in different sections of the Atlantic Ocean. (C) 2005 Elsevier B.V. All rights reserved.