Reconstruction of sea-surface temperature, salinity, and sea-ice cover in the northern North Atlantic during the last glacial maximum based on dinocyst assemblages
Reconstruction of sea-surface temperature, salinity, and sea-ice cover in the northern North Atlantic during the last glacial maximum based on dinocyst assemblages
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基于恐龙囊组合重建末次盛冰期北大西洋北部海面温度、盐度和海冰覆盖
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发表时间：
2000
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通讯作者：
J. Matthiessen
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作者：
A. Vernal;C. Hillaire‐Marcel;J. Turon;J. Matthiessen
通过对61个深海岩心的研究，研究了北大西洋北部在最后一次冰川盛期期间的过去海面状况。这里研究的最后一个冰期最大时间片对应于海因里士层H2和H1之间的间隔，在14C时间尺度上跨度约为20-16ka。基于海藻组合的传递函数被用来重建海表面温度、盐度和海冰覆盖。结果表明，加拿大东部边缘的海冰覆盖范围很广，海冰只在冬季在北大西洋北部的大部分地区扩散。总体而言，尽管8月份的天气相对温和(大多数离岸站点的气温为10-15摄氏度)，但冬季的天气要冷得多，这表明气温的季节性差异比今天更大。比目前更低的盐度被重建，特别是沿着加拿大东部和斯堪的纳维亚边缘，可能是因为周围冰盖融化的水供应。这些重建与CLIMAP在浮游有孔虫基础上建立的结果形成了对比。最后一次冰期高峰期的地层格架不是最后一次冰期阶段的最冷阶段，对这些差异进行了讨论。根据表层水的温盐特征和上层水团的垂直结构，还考察了恐囊和有孔虫记录的各自意义，这些水团明显比目前北大西洋北部更具层次性，从而防止了深水的形成。
Past sea-surface conditions over the northern North Atlantic during the last glacial maximum were examined from the study of 61 deep-sea cores. The last glacial maximum time slice studied here corresponds to an interval between Heinrich layers H2 and H1, and spanningabout 20-16 ka on a 14C time scale. Transfer functions based on dinocyst assemblages were used to reconstruct sea-surface temperature, salinity, and sea-ice cover. The results illustrate extensive sea-ice cover along the eastern Canadian margins and sea-ice spreading, only during winter, over most of the northern North Atlantic. On the whole, much colder winter prevailed, despite relatively mild conditions in August (10-15°C at most offshore sites), thus suggesting a larger seasonal contrast of temperatures than today. Lower salinity than at present is reconstructed, especially along the eastern Canadian and Scandinavian margins, likely because of meltwater supply from the surrounding ice sheets. These reconstructions contrast with those established by CLIMAP on the basis of planktonic foraminifera. These differences are discussed with reference to the stratigraphical frame of the last glacial maximum, which was not the coldest phase of the last glacial stage. The respective significance of dinocyst and foraminifer records is also examined in terms of the thermohaline characteristics of surface waters and the vertical structure of upper water masses, which was apparently much more stratified than at present in the northern North Atlantic, thus preventing deep-water formation.