Elevated East Antarctic outlet glaciers during warmer-than-present climates in southern Victoria Land
Elevated East Antarctic outlet glaciers during warmer-than-present climates in southern Victoria Land
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DOI：
10.1016/j.gloplacha.2011.07.012
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发表时间：
2010-12
影响因子：
3.9
通讯作者：
Kate M. Swanger;D. Marchant;J. Schaefer;G. Winckler;J. Head
中科院分区：
文献类型：
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作者：
Kate M. Swanger;D. Marchant;J. Schaefer;G. Winckler;J. Head
我们记录上新世更新世的变化，泰勒冰川，在南部维多利亚地排水泰勒圆顶的东南极冰盖（EAIS）的外围出口冰川的水平。年代控制来自3 He宇宙成因核素分析的27块巨石样品从漂移和冰碛在肯纳谷，一个小的悬谷，打开到泰勒冰川的周边叶在夸特梅因山脉。假设巨石侵蚀速率为10 cmMyr −1，我们的年龄模型跨越了过去的310万年，并要求从肯纳山谷口泰勒冰川现在的底部以上约200米的局部高点开始进行阶梯式冰衰退。所有绘制的冰碛和漂流物的纹理和沉积学表明，沉积来自冷基冰，类似于肯纳山谷口的现代泰勒冰川。肯纳谷的冰川记录显示出与全球平均气温的非典型关系，在全球温暖时期，包括上新世气候最佳时期（~3.1Ma）和海洋氧同位素阶段（MIS）31（~1.07Ma），冰川水平高于现在。肯纳谷的记录还表明，在中更新世过渡期后，冰面下降的速度在0.9Ma左右加快。我们的冰碛记录与发表的报告泰勒冰川在夸特梅因山脉的其他地方的波动，并与一个过时的冰碛记录从Ferrar冰川（泰勒圆顶的第二个出口）的相关性，揭示了类似的冰面变化，突出了轻微的，但广泛的冰衰退南部维多利亚土地自上新世中期至晚期。我们的记录在东南极冰盖的最小变化与最近的数据从附近的海洋核心，呼吁在罗斯湾的接地冰的体积的动态波动，并显着减少南极西部冰盖（WAIS）在温暖比现在的间隔。两者合计，这些记录从罗斯湾呼吁相当大的变化，以海洋为基础的南极西部冰和陆地南极东部出口冰川在上新世更新世的时间。
We document Plio-Pleistocene changes in the level of Taylor Glacier, an outlet glacier in southern Victoria Land that drains Taylor Dome on the periphery of the East Antarctic Ice Sheet (EAIS). Chronologic control comes from3He cosmogenic-nuclide analyses of 27 boulders sampled from drifts and moraines in Kennar Valley, a small hanging valley that opens onto a peripheral lobe of Taylor Glacier in the Quartermain Mountains. Assuming a constant boulder-erosion rate of 10cmMyr−1, our preferred age model spans the last 3.1Myr and calls for stepped ice recession from a local highstand ~200m above the present base of Taylor Glacier at the mouth of Kennar Valley. The texture and sedimentology of all mapped moraines and drifts indicate deposition from cold-based ice, analogous with the modern Taylor Glacier at the mouth of Kennar Valley. The Kennar Valley glacial record shows an uncharacteristic relationship with average global temperatures, exhibiting higher-than-present ice levels during globally warm periods, including the Pliocene climatic optimum (~3.1Ma) and Marine Oxygen Isotope Stage (MIS) 31 (~1.07Ma). The Kennar Valley record also suggests that the rate of ice-surface lowering accelerated after the mid-Pleistocene transition at ~0.9Ma. Correlation of our moraine record with published reports for fluctuations of Taylor Glacier elsewhere in the Quartermain Mountains, and with a dated moraine record from Ferrar Glacier (a second outlet for Taylor Dome), reveals similar ice-surface changes, highlighting minor, but widespread ice recession in southern Victoria Land since the mid- to late-Pliocene. Our record for minimal variability in the East Antarctic Ice Sheet contrasts with recent data from nearby marine cores that call for dynamic fluctuations in the volume of grounded ice in the Ross Embayment, and significant reduction of the West Antarctic Ice Sheet (WAIS) during warmer-than-present intervals. Taken together, these records from the Ross Embayment call for considerable variation in the response of marine-based West Antarctic ice and terrestrial East Antarctic outlet glaciers during Plio-Pleistocene time.