Neodymium isotope evidence for coupled Southern Ocean circulation and Antarctic climate throughout the last 118,000 years
Neodymium isotope evidence for coupled Southern Ocean circulation and Antarctic climate throughout the last 118,000 years
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过去 118,000 年南大洋环流和南极气候耦合的钕同位素证据
DOI：
10.1016/j.quascirev.2021.106915
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发表时间：
2021
影响因子：
4
通讯作者：
Glaubke, Ryan
中科院分区：
文献类型：
--
作者：
Williams, Thomas John;Martin, Ellen E.;Sikes, Elisabeth;Starr, Aidan;Umling, Natalie E.;Glaubke, Ryan
围绕末次冰期循环开始和加剧的一连串事件仍然相对知之甚少。特别是，南大洋古环流变化的作用是不受约束的，部分原因是缺乏沉积记录，从这个地区。在这项研究中，我们提出了多代理数据-包括钕同位素和可分选的淤泥测量-在深（3167米水深）的南大洋印度部分的古循环变化的一个新的沉积物芯，TT 1811 - 34 GGC（41.718°S，80.163°E）。我们发现在过去的118，000年中，即使在海洋同位素阶段（MIS）5.4至5.1的冰川开始的初始阶段，环流变化，南极气候和大气CO2浓度之间也存在紧密的耦合。我们发现，冷却期对应于北南极源沃茨在南大洋深处的夹带减少，证明了更多的放射性钕同位素值的深水洗澡我们的核心网站。冷却也对应于通常较慢的底层水流速，如由更细的可分选的淤泥粒度级所指示的。MIS 5.4-5.1期间，大西洋环流较强，北大西洋来源的沃茨水的夹带减少，这表明南半球控制了当时的古环流变化。我们假设，在MIS 5.4期间，南大洋海冰的扩大增加了南大洋深层的密度，降低了南极源沃茨混合成低绕极深层水的能力。这导致太平洋深层水在低环流圈内的贡献扩大，并增加了南大洋深层的分层。这些古环流的变化可以帮助解释大气CO2在MIS 5.5到5.4过渡期间的减少，并有助于解释末次冰期的事件链。
The chain of events surrounding the initiation and intensification of the last glacial cycle remain relatively poorly understood. In particular, the role of Southern Ocean paleocirculation changes is poorly constrained, in part, owing to a paucity of sedimentary records from this region. In this study we present multiproxy data – including neodymium isotope and sortable silt measurements – for paleocirculation changes within the deep (3167 m water depth) Indian sector of the Southern Ocean from a new sediment core, TT1811-34GGC (41.718°S, 80.163°E). We find a tight coupling between circulation changes, Antarctic climate, and atmospheric CO2concentrations throughout the last 118,000 years, even during the initial stages of glacial inception of Marine Isotope Stage (MIS) 5.4 to 5.1. We find that periods of cooling correspond to reductions in the entrainment of North Atlantic-sourced waters within the deep Southern Ocean, as evidenced by more radiogenic neodymium isotope values of deep water bathing our core site. Cooling also corresponds to generally slower bottom water flow speeds, as indicated by finer sortable silt size fractions. A reduction in entrainment of North-Atlantic sourced waters occurred during MIS 5.4–5.1, when Atlantic circulation was strong, suggesting a Southern hemisphere control on paleocirculation changes at that time. We hypothesise that expanded Southern Ocean sea-ice during MIS 5.4 increased the density of the deep Southern Ocean, reducing the ability of Atlantic-sourced waters to mix into Lower Circumpolar Deep Water. This led to an expanded contribution of Pacific Deep Water within the lower circulation cell and increased stratification within the deep Southern Ocean. These paleocirculation changes can help account for the reduction in atmospheric CO2across the MIS 5.5 to 5.4 transition, and in doing so help explain the chain of events surrounding the decent into the last glacial period.
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DOI：
--
发表时间：
1991
期刊：
影响因子：
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作者：
Young‐Hyang Park;L. Gamberoni;E. Charriaud
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DOI：
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发表时间：
1997
期刊：
影响因子：
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作者：
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DOI：
10.1016/j.dsr.2019.103135
发表时间：
2019-12
期刊：
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影响因子：
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影响因子：
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T. Stichel;M. Frank;J. Rickli;B. Haley
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David J. Wilson;T. Struve;T. van de Flierdt;Tianyu Chen;Tao Li;A. Burke;L. Robinson