Department of Earth Science and Engineering, Imperial College London, SW7 2AZ, London, UK.
The Grantham Institute for Climate Change and the Environment, Imperial College London, SW7 2AZ, London, UK.
Nat Commun. 2022 Jun 30;13(1):3763. doi: 10.1038/s41467-022-31116-7.
The interoceanic exchange of water masses is modulated by flow through key oceanic choke points in the Drake Passage, the Indonesian Seas, south of Africa, and south of Tasmania. Here, we use the neodymium isotope signature (ε) of cold-water coral skeletons from intermediate depths (1460‒1689 m) to trace circulation changes south of Tasmania during the last glacial period. The key feature of our dataset is a long-term trend towards radiogenic ε values of ~-4.6 during the Last Glacial Maximum and Heinrich Stadial 1, which are clearly distinct from contemporaneous Southern Ocean ε of ~-7. When combined with previously published radiocarbon data from the same corals, our results indicate that a unique radiogenic and young water mass was present during this time. This scenario can be explained by a more vigorous Pacific overturning circulation that supported a deeper outflow of Pacific waters, including North Pacific Intermediate Water, through the Tasman Sea.
水体的跨洋交换受到德雷克海峡、印度尼西亚海、非洲南部和塔斯马尼亚岛南部等关键海洋咽喉处的流量调节。在这里，我们利用来自中间深度（1460-1689 米）冷水珊瑚骨骼的钕同位素特征（ε）来追踪塔斯马尼亚岛南部在末次冰期期间的环流变化。我们数据集的关键特征是在末次冰盛期和 Heinrich 冰期 1 期间，ε 值长期呈现放射性特征，约为-4.6，这与同期南大洋的 ε 值约为-7 明显不同。当与同一珊瑚的先前发表的放射性碳数据结合时，我们的结果表明，在此期间存在一种独特的放射性和年轻水团。这种情况可以通过更强烈的太平洋翻转环流来解释，该环流支持更多的太平洋水通过塔斯曼海流出，包括北太平洋中层水。
