Local and regional controls on Holocene sea ice dynamics and oceanography in Nares Strait, Northwest Greenland
Local and regional controls on Holocene sea ice dynamics and oceanography in Nares Strait, Northwest Greenland
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DOI：
10.1016/j.margeo.2020.106115
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发表时间：
2020-04-01
期刊：
影响因子：
2.9
通讯作者：
Masse, Guillaume
中科院分区：
文献类型：
--
作者：
Georgiadis, Eleanor;Giraudeau, Jacques;Masse, Guillaume
纳雷斯海峡是连接北冰洋和巴芬湾的三条海峡之一。海峡独特的海冰条件导致在其北方和南端形成了不动陆的冰拱。这些冰拱调节了北极海冰和淡水通过海峡的输出，并促进了北水冰穴的开放。本研究解决了缺乏卫星前记录的环境条件在纳雷斯海峡地区，并旨在重建全新世海冰条件和海洋环流在海峡。该调查是基于海洋沉积物核心战略检索下目前的冰拱在凯恩盆地的纳雷斯海峡南部，并提供了一个连续的记录跨越过去约9 kyrs。我们使用底栖有孔虫组合和海冰生物标志物来推断全新世海洋环流和海冰条件在凯恩盆地的变化。凯恩盆地现代海洋环流的建立与冰盖退缩和冰后期反弹有关，而海冰覆盖的变化与北极涛动（AO）的重大变化一致。我们的研究结果表明，在凯恩盆地的海冰覆盖是高度可变的约9.0和8.3 cal.ka BP，增加之前，可能与8.2冷事件和开放的纳雷斯海峡。一个短时期的最小海冰覆盖和最大的大西洋底层水的影响发生在约8.1和7.5卡。ka BP，当凯恩盆地深于全新世的其余部分。随着大气温度的下降，海冰覆盖加剧凯恩盆地之间约7.5和5.5 cal. ka BP，但强风下普遍积极的AO条件下可能会阻止冰拱的形成在内尔斯海峡。在此期间，我们的微体古生物学数据表明，大西洋水逐渐排除凯恩盆地的冰后期均衡反弹。越来越冷的大气温度和转向更负阶段的AO可能促进了建立冰拱在纳雷斯海峡之间约5.5和3.0 cal.ka BP。凯恩盆地冰拱约3.0卡尔。ka BP的不稳定性与AO向盛行正相的转变相吻合，而冰拱的短暂恢复发生在更负的AO条件之间约1.2和0.2卡尔。ka BP。
Nares Strait is one of three channels that connect the Arctic Ocean to Baffin Bay. Unique sea-ice conditions in the strait lead to the formation of landfast ice arches at its northern and southern ends. These ice arches regulate Arctic sea-ice and freshwater export through the strait and promote the opening of the North Water polynya. The present study addresses the paucity of pre-satellite records of environmental conditions in the Nares Strait area, and aims at reconstructing Holocene sea-ice conditions and ocean circulation in the strait. The investigation is based on a marine sediment core strategically retrieved from under the current ice arch in Kane Basin to the south of Nares Strait, and provides a continuous record spanning the past ca 9 kyrs. We use benthic foraminiferal assemblages and sea-ice biomarkers to infer changes in Holocene ocean circulation and sea-ice conditions in Kane Basin. The establishment of the modern ocean circulation in Kane Basin is related to ice sheet retreat and postglacial rebound, while changes in sea-ice cover concur with major shifts in the Arctic Oscillation (AO). Our results suggest that sea-ice cover in Kane Basin was highly variable between ca 9.0 and 8.3 cal. ka BP, before increasing, probably in link with the 8.2 cold event and the opening of Nares Strait. A short period of minimum sea-ice cover and maximum Atlantic bottom water influence occurred between ca 8.1 and 7.5 cal. ka BP, when Kane Basin was deeper than for the remaining of the Holocene. As atmospheric temperatures dropped, sea-ice cover intensified in Kane Basin between ca 7.5 and 5.5 cal. ka BP, but strong winds under prevailing positive-like AO conditions likely prevented the formation of ice arches in Nares Strait. During this time, our micropaleontological data show that Atlantic water was progressively excluded from Kane Basin by the postglacial isostatic rebound. Increasingly cooler atmospheric temperatures and a shift towards more negative phases of the AO may have promoted the establishment of ice arches in Nares Strait between ca 5.5 and 3.0 cal. ka BP. Instabilities in the Kane Basin ice arch ca 3.0 cal. ka BP coincide with a shift towards prevailing positive phases of the AO, while a brief recovery of the ice arch occurred during more negative-like AO conditions between ca 1.2 and 0.2 cal. ka BP.