Moran Kathryn, Backman Jan, Brinkhuis Henk, Clemens Steven C, Cronin Thomas, Dickens Gerald R, Eynaud Frédérique, Gattacceca Jérôme, Jakobsson Martin, Jordan Richard W, Kaminski Michael, King John, Koc Nalan, Krylov Alexey, Martinez Nahysa, Matthiessen Jens, McInroy David, Moore Theodore C, Onodera Jonaotaro, O'Regan Matthew, Pälike Heiko, Rea Brice, Rio Domenico, Sakamoto Tatsuhiko, Smith David C, Stein Ruediger, St John Kristen, Suto Itsuki, Suzuki Noritoshi, Takahashi Kozo, Watanabe Mahito, Yamamoto Masanobu, Farrell John, Frank Martin, Kubik Peter, Jokat Wilfried, Kristoffersen Yngve
Graduate School of Oceanography & Department of Ocean Engineering, University of Rhode Island, Narragansett, Rhode Island 02882, USA.
Nature. 2006 Jun 1;441(7093):601-5. doi: 10.1038/nature04800.
The history of the Arctic Ocean during the Cenozoic era (0-65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from >400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm 'greenhouse' world, during the late Palaeocene and early Eocene epochs, to a colder 'icehouse' world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent approximately 14 Myr, we find sedimentation rates of 1-2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (approximately 3.2 Myr ago) and East Antarctic ice (approximately 14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (approximately 45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at approximately 49 Myr ago, before the onset of ice-rafted debris. Also, the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (approximately 55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change.
由于缺乏直接证据，新生代（0 - 6500万年前）北冰洋的历史在很大程度上尚不为人所知。在此，我们展示了一份新生代古海洋学记录，该记录是根据最近一次北冰洋罗蒙诺索夫海岭钻探探险获取的超过400米沉积岩芯构建而成。我们的记录显示了一个古环境转变，从晚古新世和早始新世时期温暖的“温室”世界，转变为从中始新世时期至今受海冰和冰山影响的较冷的“冰室”世界。在最近大约1400万年里，我们发现沉积速率为每千年1 - 2厘米，这与早期研究提出的显著更低的速率形成鲜明对比；新近纪的这份记录揭示了北极的变冷与格陵兰冰盖扩张（约320万年前）和东南极冰盖扩张（约1400万年前）是同步的。我们发现证据表明，在中始新世时期（约4500万年前）首次出现了冰筏碎屑，比之前认为的早约3500万年；在冰筏碎屑出现之前，约4900万年前存在新鲜地表水。此外，古新世/始新世极热事件期间（约5500万年前）的地表水温度似乎比之前估计的要高得多。最早的北极变冷事件时间的修订与南极洲的时间一致，支持了气候变化中两极对称性的观点。
