The large MIS 4 and long MIS 2 glacier maxima on the southern tip of South America
The large MIS 4 and long MIS 2 glacier maxima on the southern tip of South America
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南美洲南端的大 MIS 4 和长 MIS 2 冰川极大期
DOI：
10.1016/j.quascirev.2021.106858
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发表时间：
2021
影响因子：
4
通讯作者：
Schaefer, Joerg M.
中科院分区：
文献类型：
--
作者：
Peltier, Carly;Kaplan, Michael R.;Birkel, Sean D.;Soteres, Rodrigo L.;Sagredo, Esteban A.;Aravena, Juan Carlos;Araos, José;Moreno, Patricio I.;Schwartz, Roseanne;Schaefer, Joerg M.
要解决冰河时代气候开始和结束的时间和原因等基本问题，就需要可靠的冰川年表。南美洲最南端Estrecho de Magallanes（53°S；智利）附近的大型冰原裂片留下了保存完好的冰川沉积物，为重建最后两个主要冰川的时间和精细结构以及最后一次终止提供了独特的机会。我们提出了一个新的精确的10be表面暴露数据集，包含34个冰碛巨石，直接与最近发表的麦哲伦裂片留下的沉积物的高分辨率冰川地形图相关联。我们发现，在海洋同位素阶段4 （MIS 4）期间，巴塔哥尼亚冰盖的南段比MIS 2期间更广泛，代表了南美洲MIS 4冰川高潮的第一次直接测年。与MIS 2冰川极大期相似，在MIS 4中，我们确定（n = 6个样本）在67.5±2.1和62.1±2.0 ka之间有多个进展。在新西兰也发现了类似时间的MIS 4推进，表明这是一个半球范围的冰川气候信号，南大西洋和太平洋的温度代理记录进一步证实了这一点。在MIS 4冰碛复合体的内部，我们确定了一系列地貌上不同的MIS 2冰碛的年代，它们代表了冰川稳定的不同主要时期。MIS 2最大程度上发生27.4±0.8 ka (n = 4;算术平均值,平均数标准误差和3%产量传播错误),其次是至少四个完整的冰川上文25.7±0.8 (n = 3), 23.9±0.8 (n = 5), 19.1±0.7 (n = 3),和18.1±0.6 ka (n = 3),代表时期冰川处于平衡状态时的气候足够长的时间形成主要碛。在向内约18公里处，这个序列之后是较小规模的退潮冰碛峰，沉积在鼓状地形上，而不是冰碛漂移上，我们将其追溯到18.0±0.8 ka，表明冰川在这个时候处于净退缩状态。二维冰盖模型的初步结果表明，麦哲伦裂片可能是在夏季温度分别较低约4.5°C和5.5°C的气候条件下到达MIS 2的内部和外部冰碛的，假设年降水量相对于现代气候减少约25%。我们假设，在末次冰期旋回期间，副热带和亚南极锋面的变化以及相关的海洋-大气模式可以解释中纬度南部的MIS 4至2冰川行为。
Robust glacial chronologies are needed to address the fundamental questions of when and why Ice Age climates begin and end. Well-preserved glacial deposits left by large ice sheet lobes adjacent to Estrecho de Magallanes (53°S; Chile) in southernmost South America provide a unique opportunity to reconstruct the timing and fine structure of the last two major glaciations, as well as the last termination. We present a new precise10Be surface exposure dataset of 34 moraine boulders directly tied to a recently published, high resolution glacial geomorphic map of the deposits left by the Magallanes lobe.We find that the southern section of the Patagonian Ice Sheet was more extensive during Marine Isotope Stage 4 (MIS 4) than during MIS 2, representing the first direct dating of the MIS 4 glacier culmination in South America. Similar to the MIS 2 glacial maxima, within MIS 4 there were multiple advances that we date (n = 6 samples) to between 67.5 ± 2.1 and 62.1 ± 2.0 ka. A similarly timed MIS 4 advance was identified in New Zealand, indicating that this is a hemisphere-wide glacier-climate signal, which is further corroborated by South Atlantic and Pacific temperature proxy records. Inboard of the MIS 4 moraine complex, we date a sequence of geomorphically distinct MIS 2 moraines that represent separate major periods of glacial stability. The MIS 2 maximum extent occurred by 27.4 ± 0.8 ka (n = 4; arithmetic mean, with the standard error of the mean and 3% propagated production rate error) and was followed by at least four more full glacial culminations at 25.7 ± 0.8 (n = 3), 23.9 ± 0.8 (n = 5), 19.1 ± 0.7 (n = 3), and 18.1 ± 0.6 ka (n = 3), which represent periods when the glacier was in equilibrium with the climate for long enough to form major moraines. About 18 km inboard, this sequence is followed by smaller-scale recessional moraine crests, deposited on drumlinized terrain rather than a moraine drift, that we date to 18.0 ± 0.8 ka, indicating the glacier was in net retreat at this time. Tentative results from a 2D ice sheet model suggest that the Magallanes lobe may have reached mapped inner and outer MIS 2 moraines from a climate with approximately 4.5 °C and 5.5 °C cooler summers, respectively, assuming ∼25% less annual precipitation, relative to modern climate. We hypothesize that during the last glacial cycle, shifts in the subtropical and subantarctic fronts, and related ocean-atmosphere patterns, explain MIS 4 to 2 glacial behavior in the southern mid-latitudes.
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影响因子：
4
作者：
J. Schaefer;A. Putnam;G. Denton;M. Kaplan;S. Birkel;A. Doughty;Sam Kelley;D. Barrell;Robert C. Finkel;G. Winckler;Robert F. Anderson;U. Ninneman;S. Barker;R. Schwartz;B. G. Andersen;C. Schluechter
通讯作者：
J. Schaefer;A. Putnam;G. Denton;M. Kaplan;S. Birkel;A. Doughty;Sam Kelley;D. Barrell;Robert C. Finkel;G. Winckler;Robert F. Anderson;U. Ninneman;S. Barker;R. Schwartz;B. G. Andersen;C. Schluechter
影响因子：
5.8
作者：
Doughty, Alice M.;Schaefer, Joerg M.;Schwartz, Roseanne
通讯作者：
Schwartz, Roseanne
影响因子：
5.3
作者：
Kaplan, Michael R.;Strelin, Jorge A.;Travis, Scott G.
通讯作者：
Travis, Scott G.
末次盛冰期和终止期间智利巴塔哥尼亚 Última Esperanza 冰瓣（南纬 52°）的波动 1
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
E. Sagredo;P. Moreno;R. Villa;M. Kaplan;P. Kubik;C. Stern
通讯作者：
C. Stern
南美洲最南端的宇宙成因核素测量及其对景观变化的影响
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
M. Kaplan;A. Coronato;N. Hulton;J. Rabassa;P. Kubik;S. Freeman
通讯作者：
S. Freeman