Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)
Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)
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艾克湖（南52°，阿根廷）湖水氧同位素重建揭示南半球西风带末次冰期-间冰期转换期间的气候历史
DOI：
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
B. Zolitschka
中科院分区：
文献类型：
--
作者：
Jiayun Zhu;A. Lücke;H. Wissel;C. Mayr;D. Enters;K. J. Kim;C. Ohlendorf;F. Schäbitz;B. Zolitschka
抽象的。南半球西风带（SHW）在大规模海洋环流和全球碳循环中发挥着至关重要的作用。因此，重建末次冰期末期SHW带的纬度位置和强度如何变化对于理解全球气候波动至关重要。南美大陆最南端是唯一与SHW带大部分相交的大陆块。然而，由于缺乏合适的古气候档案，追溯到末次冰期的连续代理记录在巴塔哥尼亚南部很少见。在这里，我们展示了来自 Laguna Potrok Aike（南纬 52°，西经 70°）的水下水生苔藓芽的纤维素和纯化的大量有机物的氧同位素记录，这是一个位于半干旱、安第斯山脉外巴塔哥尼亚的玛珥深湖，覆盖了最后一次冰期-间冰期过渡期（26 000 至 8500 cal BP）。基于现代水生苔藓及其寄主水域的氧同位素值之间的高度显着相关性以及沉积物记录中保存完好的丰富苔藓遗迹，提出了湖水氧同位素（δ18Olw-corr）组成的高分辨率重建。末次冰期的重建δ18Olw-corr值约为。比现代值低3‰，最好的解释是气温普遍较低、水汽源区的变化，以及永久冻土的出现导致湖水停留时间延长。因此，直到 21 000 cal BP 之前的总体冰川 δ18Olw-corr 水平与南纬 52°SHW 与现在相比减弱或缺失的情况一致。在最后一次冰消期期间，重建的 δ18Olw-corr 值揭示了显着的两步上升，描述了湖泊水文平衡对这一基本气候变化的详细响应。快速变暖被认为是大约第一次上升的原因。 2&permil，在冰川消退的前两千年（17 600 至 15 600 cal BP）期间的 δ18Olw-corr 中，由于更多 18O 富集降水和温度引起的蒸发增加。根据这一解释，早期加强 SHW 是没有必要的。随后 δ18Olw-corr 下降高达 0.7‰，标志着 15 600 至 14 600 cal BP 之间的千年尺度过渡期，被解释为从由温度引起的蒸发驱动的系统向以风引起的蒸发为主的系统的转变。 δ18Olw-corr 记录在 14 600 cal BP 左右恢复其明显增加。湖水中 18O 的进一步累积富集可以解释为对自 14 600 cal BP 以来在 Laguna Potrok Aike 纬度（52°S）的 SHW 的加强和建立所引起的风驱动蒸发加强的响应。 δ18Olw-corr 在 8500 cal BP 左右接近现代值，这表明 SHW 对当时的湖泊水平衡产生了充分的影响，导致了 Laguna Potrok Aike 地区普遍存在更加干旱的草原气候。
Abstract. The Southern Hemisphere Westerlies (SHW) play a crucial role in large-scale ocean circulation and global carbon cycling. Accordingly, the reconstruction of how the latitudinal position and intensity of the SHW belt changed during the last glacial termination is essential for understanding global climatic fluctuations. The southernmost part of the South American continent is the only continental mass intersecting a large part of the SHW belt. However, due to the scarcity of suitable palaeoclimate archives continuous proxy records back to the last glacial are rare in southern Patagonia. Here, we show an oxygen isotope record from cellulose and purified bulk organic matter of submerged aquatic moss shoots from Laguna Potrok Aike (52° S, 70° W), a deep maar lake located in semi-arid, extra-Andean Patagonia, covering the last glacial–interglacial transition (26 000 to 8500 cal BP). Based on the highly significant correlation between oxygen isotope values of modern aquatic mosses and their host waters and abundant well-preserved moss remains in the sediment record a high-resolution reconstruction of the lake water oxygen isotope (δ18Olw-corr) composition is presented. The reconstructed δ18Olw-corr values for the last glacial are ca. 3‰ lower than modern values, which can best be explained by generally cooler air temperatures and changes in the moisture source area, together with the occurrence of permafrost leading to a prolonged lake water residence time. Thus, the overall glacial δ18Olw-corr level until 21 000 cal BP is consistent with a scenario of weakened or absent SHW at 52° S compared to the present. During the last deglaciation, reconstructed δ18Olw-corr values reveal a significant two-step rise describing the detailed response of the lake's hydrological balance to this fundamental climatic shift. Rapid warming is seen as the cause of the first rise of ca. 2&permil, in δ18Olw-corr during the first two millennia of deglaciation (17 600 to 15 600 cal BP) owing to more 18O enriched precipitation and increasing temperature-induced evaporation. Following this interpretation, an early strengthening of the SHW would not be necessary. The subsequent decrease in δ18Olw-corr by up to 0.7‰ marks a millennial-scale transition period between 15 600 and 14 600 cal BP interpreted as the transition from a system driven by temperature-induced evaporation to a system more dominated by wind-induced evaporation. The δ18Olw-corr record resumes its pronounced increase around 14 600 cal BP. This further cumulative enrichment in 18O of lake water could be interpreted as response to strengthened wind-driven evaporation as induced by the intensification and establishment of the SHW at the latitude of Laguna Potrok Aike (52° S) since 14 600 cal BP. δ18Olw-corr approaching modern values around 8500 cal BP reflect that the SHW exerted their full influence on the lake water balance at that time provoking a prevailing more arid steppe climate in the Laguna Potrok Aike region.
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影响因子：
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作者：
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DOI：
10.1177/0959683611429833
发表时间：
2012
期刊：
The Holocene
影响因子：
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作者：
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