Ice-sheet expansion from the Ross Sea into McMurdo Sound, Antarctica, during the last two glaciations
Ice-sheet expansion from the Ross Sea into McMurdo Sound, Antarctica, during the last two glaciations
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DOI：
10.1016/j.quascirev.2022.107379
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发表时间：
2022-02
影响因子：
4
通讯作者：
Stephanie L. Heath;B. Hall;G. Denton;G. Henderson;C. Hendy
中科院分区：
文献类型：
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作者：
Stephanie L. Heath;B. Hall;G. Denton;G. Henderson;C. Hendy
了解南极冰盖（AIS）的行为对未来的海平面预测很重要。在这里，我们研究过去的冰盖历史在西部罗斯海的麦克默多声音地区在过去的两个冰川间冰期周期，以深入了解冰盖变化的驱动因素。地表水测绘，沿着与放射性碳测年的湖藻和铀钍不平衡的湖泊碳酸盐的冰坝湖泊，允许重建的时间和起源的接地冰在麦克默多声音在末次盛冰期（LGM）和倒数第二次冰期。在末次冰期，冰面海拔剖面和分布的erratics表明，冰流入南部麦克默多声音从罗斯海，而不是从皇家协会范围的当地冰川向海扩展。麦克默多湾的冰向西流动，堵住了皇家学会山脉的谷口，并对冰前湖形成了堤坝。在马歇尔谷，最大的冰范围在什么被称为罗斯海冰期，实现了18 ka，并保持接近这个位置，直到14 ka后。表层沉积物的模式表明，冰在倒数第二次冰期，当地命名的马歇尔冰期，是稍微更广泛的比末次冰期，但有类似的罗斯海的起源。马歇尔山谷最大冰的范围发生在距今145-150 ka; 138 ka后不久，地面冰可能已经从谷口消退。这两次冰的扩张都发生在南极气温较低的时期，这与太阳能最低值有关。然而，AIS上缺乏广泛的表面融化消融区表明，冰膨胀和轨道强迫之间的联系可能是间接的，可能是通过海洋驱动的。对马歇尔山谷冰川最大期的精确时间进行更仔细的研究表明，马歇尔冰川作用与倒数第二个全球最大期同步发生;冰衰退发生在终止II期间。相反，最大的冰范围在罗斯海冰川沿着皇家协会范围发生在全球末次盛冰期之后，在终止I。冰川消退主要是全新世早期的事件。我们将这种延迟的最大和冰川消退（相对于全球事件）的影响，冰盖质量平衡的积累上升。
An understanding of Antarctic Ice Sheet (AIS) behavior is important for future sea-level predictions. Here, we examine past ice-sheet history in the McMurdo Sound region of the western Ross Sea over the last two glacial-interglacial cycles in order to gain insight into the drivers of ice-sheet change. Surficial mapping, along with radiocarbon dates of lacustrine algae and uranium-thorium disequilibrium dates of lacustrine carbonates from ice-dammed lakes, allow reconstruction of the timing and origin of grounded ice in McMurdo Sound during the last glacial maximum (LGM) and penultimate glaciation. During the LGM, ice-surface elevation profiles and distribution of erratics indicate ice flow into southern McMurdo Sound from the Ross Sea, rather than seaward expansion of local glaciers from the Royal Society Range. The grounded ice in McMurdo Sound flowed westward to block the mouths of valleys in the Royal Society Range and to dam proglacial lakes. In Marshall Valley, maximum ice extent during what is termed the Ross Sea glaciation, was achieved by 18 ka and remained close to this position until after 14 ka. The pattern of surficial deposits suggests that ice during the penultimate glaciation, locally named the Marshall glaciation, was slightly more extensive than that of the LGM but had a similar Ross Sea origin. Maximum ice extent in Marshall Valley occurred at ∼145–150 ka; the grounded ice may have receded from the valley mouth shortly after 138 ka. Both ice expansions occurred broadly during times of low Antarctic air temperatures, which have been linked to insolation minima. However, the lack of widespread surface melting ablation zones on the AIS indicates that the link between ice expansion and orbital forcing is likely to be indirect and possibly driven through the ocean. Closer examination of the precise timing of the glacial maxima in Marshall Valley shows that the Marshall glaciation occurred synchronously with the penultimate global maximum; ice recession took place during Termination II. In contrast, maximum ice extent during the Ross Sea glaciation along the Royal Society Range occurred after the global LGM, during Termination I. Deglaciation was primarily an early Holocene event. We attribute this delayed maximum and deglaciation (relative to global events) to the effect of rising accumulation on ice-sheet mass balance.