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晚中新世现代南极环极流的开始
作者:小柯机器人 发布时间:2024/1/20 20:33:28

西班牙巴塞罗那大学Evangelinos, Dimitris小组的一项最新研究揭示了晚中新世现代南极环极流的开始。2024年1月18日,国际知名学术期刊《自然—地球科学》发表了这一成果。

研究团队展示了过去3100万年中,来自西南太平洋和南印度洋沉积物岩芯的钕同位素和可分类的泥沙记录。数据显示,在中新世晚期变冷之前,像今天这样的环极洋流并不存在。研究表明,始新世—渐新世过渡期间(约34Ma),出现一股均匀而深远的强大南大洋环极流,并不仅仅与引发大陆规模南极冰盖扩张的南大洋门户开放和加深有关。

相反,研究人员发现,除了构造的预调节作用外中新世中期(约14Ma)以来,南极冰盖和海冰的扩张也起到了至关重要的作用。这导致了密度反差和穿过南大洋南方西风的增强,形成了一个强有力的深层环极流和一个增强的全球翻转环流,扩大了晚新生代全球降温。

据悉,南极环极流通过其对全球翻转环流、海洋热量和二氧化碳吸收的强大影响,在全球气候中发挥着关键作用。然而,南极环极流何时以及如何达到其类似现代的特征仍然存在争议。

附:英文原文

Title: Late Miocene onset of the modern Antarctic Circumpolar Current

Author: Evangelinos, Dimitris, Etourneau, Johan, van de Flierdt, Tina, Crosta, Xavier, Jeandel, Catherine, Flores, Jos-Abel, Harwood, David M., Valero, Luis, Ducassou, Emmanuelle, Sauermilch, Isabel, Klocker, Andreas, Cacho, Isabel, Pena, Leopoldo D., Kreissig, Katharina, Benoit, Mathieu, Belhadj, Moustafa, Paredes, Eduardo, Garcia-Solsona, Ester, Lpez-Quirs, Adrin, Salabarnada, Ariadna, Escutia, Carlota

Issue&Volume: 2024-01-18

Abstract: The Antarctic Circumpolar Current plays a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO2 uptake. However, when and how the Antarctic Circumpolar Current reached its modern-like characteristics remains disputed. Here we present neodymium isotope and sortable silt records from sediment cores in the Southwest Pacific and South Indian oceans spanning the past 31 million years. Our data indicate that a circumpolar current like that of today did not exist before the late Miocene cooling. These findings suggest that the emergence of a homogeneous and deep-reaching strong Antarctic Circumpolar Current was not linked solely to the opening and deepening of Southern Ocean Gateways triggering continental-scale Antarctic Ice Sheet expansion during the Eocene–Oligocene Transition (~34Ma). Instead, we find that besides tectonic pre-conditioning, the expansion of the Antarctic Ice Sheet and sea ice since the middle Miocene Climate Transition (~14Ma) played a crucial role. This led to stronger density contrast and intensified Southern Westerly Winds across the Southern Ocean, establishing a vigorous deep-reaching circumpolar flow and an enhanced global overturning circulation, which amplified the late Cenozoic global cooling.

DOI: 10.1038/s41561-023-01356-3

Source: https://www.nature.com/articles/s41561-023-01356-3

期刊信息
Nature Geoscience:《自然—地球科学》,创刊于2008年。隶属于施普林格·自然出版集团,最新IF:21.531