Micropaleontological and Isotopic Perspective of Surface Water Mass Variability in the NE Atlantic from MIS 6 to 5e (188 to 115 ka)
Micropaleontological and Isotopic Perspective of Surface Water Mass Variability in the NE Atlantic from MIS 6 to 5e (188 to 115 ka)
复制标题
DOI：
10.3390/geosciences13050149
复制
发表时间：
2023-05
期刊：
影响因子：
2.7
通讯作者：
H. Rashid;Jiaxin Chen;M. Menke;Min Zeng
中科院分区：
文献类型：
--
作者：
H. Rashid;Jiaxin Chen;M. Menke;Min Zeng
倒数第二次冰期（海洋同位素阶段（MIS）6）被认为是区域极端相比，最后一次冰期最大，其中欧洲冰盖有一个巨大的面积范围。与最后一次冰消期（19-7 ka）相比，倒数第二次冰消期（140-130 ka）是晚更新世最快速的海洋学变化之一。在这项研究中，我们重建的近地表和温跃层在大西洋中部到东北部的变化，通过分析沉积物从两个综合大洋钻探计划远征306网站。U1313（41°00.6′ N，32°57.4′ W）和U1314（56°21.9′ N，27°53.3′ W）分别位于中大西洋海脊和东副极地北大西洋加达漂流的东侧。我们分析了南极有孔虫组合，冰筏碎片（IRD），和氧同位素在两个南极有孔虫，Globigerina bulloides，和Globorotalia inflata，从MIS 6到5e（185-115 ka）。温暖和寒冷的海面条件的变化，标志着极地，亚极地，和过渡性浮游有孔虫的相对丰度。氧同位素在G. bulloides和G. inflata表明，温跃层加深在亚热带站点U1313在MIS 6。缺乏Globorotalia inflata阻止我们剖析混合层和温跃层在亚极地站点U1314。与MIS 6相反，混合层和温跃层在末次间冰期重新分层。在这两个网站的主要IRD事件的缺乏表明，在MIS 6的劳伦提斯冰盖的稳定性相比，随后的冰川作用。海因里希事件11的存在表明，淡水的排放，使海面清新，导致混合层和温跃层之间的混合。我们的研究结果被放置在一个更广泛的背景下，使用已公布的数据，揭示了淡水排放到北大西洋的敏感性和以下变化与从倒数第二个冰期到间冰期的过渡在表面循环。
The penultimate glaciation (marine isotope stage (MIS) 6) is considered regionally extreme compared to the last glacial maximum, in which the European ice sheets had a vast areal extent. In contrast to the last deglaciation (19–7 ka), the penultimate deglaciation (140–130 ka) hosts one of the most rapid oceanographic changes of the late Pleistocene. In this study, we reconstructed changes in the near-surface and thermocline in the central to northeast Atlantic by analyzing sediments from two Integrated Ocean Drilling Program Expedition 306 sites. Sites U1313 (41°00.6′ N, 32°57.4′ W) and U1314 (56°21.9′ N, 27°53.3′ W) were drilled on the eastern flank of the mid-Atlantic ridge and Gardar Drift of the eastern subpolar North Atlantic, respectively. We analyzed planktonic foraminiferal assemblages, ice-rafted debris (IRD), and oxygen isotopes in two planktonic foraminifers, Globigerina bulloides, and Globorotalia inflata, from MIS 6 to 5e (185–115 ka). Warmer and colder sea-surface conditions were marked by a change in the relative abundance of polar, subpolar, and transitional planktonic foraminifers. Oxygen isotopes in G. bulloides and G. inflata suggest that the thermocline deepened at the subtropical Site U1313 during MIS 6. The lack of Globorotalia inflata prevented us from profiling the mixed layer and thermocline at the subpolar Site U1314. In contrast to MIS 6, the mixed layer and thermocline were re-stratified during the last interglacial. The lack of major IRD events at both sites suggests the stability of the Laurentide ice sheet during MIS 6 compared to the subsequent glaciation. The presence of Heinrich event 11 indicates the discharge of freshwater that freshened the sea surface, resulting in mixing between the mixed layer and thermocline. Our results were placed into a broader context using published data that shed light on the sensitivity of freshwater discharge to the North Atlantic and the following changes with a transition from a penultimate glacial to an interglacial period in surface circulation.