Timing and magnitude of the sea-level jump preluding the 8200 yr event
Timing and magnitude of the sea-level jump preluding the 8200 yr event
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DOI：
10.1130/g30439.1
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发表时间：
2010-03-01
期刊：
影响因子：
5.8
通讯作者：
Cohen, Kim M.
中科院分区：
文献类型：
--
作者：
Hijma, Marc P.;Cohen, Kim M.
陆地，冰川和全球气候模型重建的证据表明，融水释放引起的海平面上升与8.2万年冷却事件的触发。然而，没有使用精确的海平面数据直接测量这种跳跃。此外，融水脉冲的年代学是基于海洋数据，其测年精度有限。触发冷却事件的最合理的机制是劳伦蒂德冰前湖阿加西斯和Ojibway通过哈德逊海峡进入北大西洋ca的突然，可能是多阶段的排水。8470 +/- 300年前。在这里，我们展示了来自荷兰鹿特丹的详细海平面数据，海平面上升开始于8450 +/- 44年前。我们的时间大大缩小了现有的年龄，这个排水事件，并提供了支持的假设，一个双阶段的湖泊排水。海平面的跳跃在200年内达到了2.11 +/- 0.89米的局部震级，除了持续的背景相对海平面上升（1.95 +/- 0.74米）。在离释放地点相当远的地方观测到的这一量级表明，全球平均海平面上升幅度是以前估计的两倍（3.0 +/- 1.2米对0.4-1.4米）。这种差异表明，要么是同时代的南极贡献，或者更有可能是以前低估了美国湖泊的总排水量。
Evidence from terrestrial, glacial, and global climate model reconstructions suggests that a sea-level jump caused by meltwater release was associated with the triggering of the 8.2 ka cooling event. However, there has been no direct measurement of this jump using precise sea-level data. In addition, the chronology of the meltwater pulse is based on marine data with limited dating accuracy. The most plausible mechanism for triggering the cooling event is the sudden, possibly multistaged drainage of the Laurentide proglacial Lakes Agassiz and Ojibway through the Hudson Strait into the North Atlantic ca. 8470 +/- 300 yr ago. Here we show with detailed sea-level data from Rotterdam, Netherlands, that the sea-level rise commenced 8450 +/- 44 yr ago. Our timing considerably narrows the existing age of this drainage event and provides support for the hypothesis of a double-staged lake drainage. The jump in sea level reached a local magnitude of 2.11 +/- 0.89 m within 200 yr, in addition to the ongoing background relative sea-level rise (1.95 +/- 0.74 m). This magnitude, observed at considerable distance from the release site, points to a global-averaged eustatic sea-level jump that is double the size of previous estimates (3.0 +/- 1.2 m versus 0.4-1.4 m). The discrepancy suggests either a coeval Antarctic contribution or, more likely, a previous underestimate of the total American lake drainage.