Millennial-scale ice rafting events and Hudson Strait Heinrich(-like) Events during the late Pliocene and Pleistocene: a review
Millennial-scale ice rafting events and Hudson Strait Heinrich(-like) Events during the late Pliocene and Pleistocene: a review
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DOI：
10.1016/j.quascirev.2013.08.014
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发表时间：
2013-11
影响因子：
4
通讯作者：
B. Naafs;J. Hefter;R. Stein
中科院分区：
文献类型：
--
作者：
B. Naafs;J. Hefter;R. Stein
各种类型的突然/千年尺度的气候变率，如Dansgaard/Oeschger和Heinrich事件，是末次冰期的特征。在过去十年中，许多研究表明，这种千年尺度的气候变化不仅限于末次冰期，而且是第四纪气候所固有的。本文回顾了上新世晚期和更新世（最近3.4Ma）北大西洋千年一次的冰漂流事件的发生和起源，特别是北大西洋哈德逊海峡（HS）Heinrich（-like）事件。使用这个框架，并结合以前发表的结果，详细的调查发现在北大西洋的冰筏碎片（IRD）的有机和无机化学表明，在MIS 16（约650 ka）IRD在北大西洋并不起源于北方加拿大的哈德逊地区。这个早期IRD的签名与HS Heinrich Layers的签名明显不同。相反，上新世晚期和更新世早期的冰筏漂流事件主要来自格陵兰岛和芬诺斯堪的纳维亚冰盖的崩解，可能还有来自北美和英国冰盖的当地冰流的微小贡献。与北大西洋HS Heinrich事件相比，这些早更新世IRD事件对北大西洋地表水特征的影响有限。北大西洋HS Heinrich（类）事件首次发生在MIS 16期间。与此同时，在富含硅酸盐的IRD积累的主导频率从垂直度（41 ka）转移到100 ka的频率横跨北大西洋。冰山的生存能力或冰山轨迹的变化可能不会控制IRD状态的这种变化。这些结果进一步支持了现有的假设，即增加的Laurentide冰盖的大小（厚度）控制北大西洋HS海因里希事件的发生，有利于其发生的内部动力学机制。
Various types of abrupt/millennial-scale climate variability such as Dansgaard/Oeschger and Heinrich Events characterized the last glacial period. Over the last decade, a number of studies demonstrated that such millennial-scale climate variability was not limited to the last glacial but inherent to Quaternary climate. Here we review the occurrence and origin of millennial ice-rafting events in the North Atlantic during the late Pliocene and Pleistocene (last 3.4 Ma) with a special focus on North Atlantic Hudson Strait (HS) Heinrich(-like) Events.We show that Heinrich Layers 5, 4, 2, and 1 in marine sediment cores from across the North Atlantic all bear the organic geochemical fingerprint of the Hudson area. Using this framework and combining previously published results, detailed investigations into the organic and inorganic chemistry of ice-rafted debris (IRD) found across the North Atlantic demonstrate that prior to MIS 16 (∼650 ka) IRD in the North Atlantic did not originate from the Hudson area of northern Canada. The signature of this early IRD is distinctly different compared to that of HS Heinrich Layers. Rather ice-rafting events during the late Pliocene and early Pleistocene predominantly emanated from the calving of the Greenland and Fennoscandian ice sheets and possibly minor contributions from local ice streams from the North American and British ice sheets. Compared to North Atlantic HS Heinrich Events, these early Pleistocene IRD-events had a limited impact on surface water characteristics in the North Atlantic. North Atlantic HS Heinrich(-like) Events first occurred during MIS 16. At the same time, the dominant frequency in silicate-rich IRD accumulation shifted from the obliquity (41-ka) to a 100-ka frequency across the North Atlantic. Iceberg survivability or a change in iceberg trajectory likely did not control this change in IRD-regime. These results lend further support for the existing hypothesis that an increase in size (thickness) of the Laurentide ice sheet controls the occurrence of North Atlantic HS Heinrich Events, favoring an internal dynamic mechanism for their occurrence.