Late Miocene onset of the modern Antarctic Circumpolar Current
Late Miocene onset of the modern Antarctic Circumpolar Current
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DOI：
10.1038/s41561-023-01356-3
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发表时间：
2024-01
影响因子：
18.3
通讯作者：
D. Evangelinos;J. Etourneau;T. van de Flierdt;X. Crosta;C. Jeandel;José-Abel Flores;D. Harwood;L. Valero;Emmanuelle Ducassou;I. Sauermilch;A. Klocker;Isabel Cacho;L. Pena;K. Kreissig;Mathieu Benoit;M. Belhadj;E. Paredes;E. Garcia-Solsona;Adrián López‐Quirós;Ariadna Salabarnada;C. Escutia
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文献类型：
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作者：
D. Evangelinos;J. Etourneau;T. van de Flierdt;X. Crosta;C. Jeandel;José-Abel Flores;D. Harwood;L. Valero;Emmanuelle Ducassou;I. Sauermilch;A. Klocker;Isabel Cacho;L. Pena;K. Kreissig;Mathieu Benoit;M. Belhadj;E. Paredes;E. Garcia-Solsona;Adrián López‐Quirós;Ariadna Salabarnada;C. Escutia
南极绕极流通过对全球翻转环流、海洋热量和二氧化碳吸收的强烈影响，在全球气候中发挥着举足轻重的作用。然而，南极绕极流何时以及如何达到现代特征仍存在争议。在这里，我们展示了过去 3100 万年西南太平洋和南印度洋沉积物岩心中的钕同位素和可分类淤泥记录。我们的数据表明，在中新世晚期冷却之前，像今天这样的环极流并不存在。这些发现表明，均匀且深入的强烈南极绕极流的出现并不仅仅与始新世-渐新世过渡期间（~34Ma）期间引发大陆规模南极冰盖扩张的南大洋门户的开放和加深有关。相反，我们发现除了构造预处理之外，中新世中期气候转变（∼14Ma）以来南极冰盖和海冰的扩张也发挥了至关重要的作用。这导致了更强的密度对比和南大洋上的南西风增强，形成了强烈的深层环极流和增强的全球翻转环流，从而加剧了新生代晚期的全球变冷。
The Antarctic Circumpolar Current plays a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO2uptake. 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 (∼34 Ma). Instead, we find that besides tectonic pre-conditioning, the expansion of the Antarctic Ice Sheet and sea ice since the middle Miocene Climate Transition (∼14 Ma) 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.