The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica
The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica
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南极洲最南端埃尔斯沃斯山脉冰川边缘线的百万年演变
DOI：
10.1016/j.epsl.2017.04.006
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发表时间：
2017
影响因子：
5.3
通讯作者：
M. Westoby
中科院分区：
文献类型：
--
作者：
D. Sugden;A. Hein;J. Woodward;S. Marrero;Á. Rodés;S. Dunning;F. Stuart;S. Freeman;Kate Winter;M. Westoby
在埃尔斯沃思山脉的西南极洲中心，一条升高的侵蚀纵倾线告诉我们过去的冰层较厚，代表了南极冰盖演变的一个重要但模糊的阶段。在这里，我们分析了最南端的遗产范围内，与纵倾线相关联的表面覆盖的surgical存款，有可能通过宇宙成因的核素分析，以确定日期的地貌。100个岩石样本的分析表明，一些碎屑已暴露在冰川塑造的表面为1.4马，也许超过3.5马，而其他反映在第四纪冰川周期的厚度波动。模拟年龄的基础上cosmogenic 10 Be，26 Al和21 Ne浓度从深度剖面的冰川塑造的基岩表面表明，最小暴露年龄为2.1-2.6马。我们的结论是，冰川侵蚀面相邻的纵倾线早于末次盛冰期，实际上是第四纪。由于侵蚀是由冰盖上缘附近的暖基冰造成的，因此我们认为它首先发生在中新世中期（1014 Ma）逐步冷却之前的南极洲早期冰川期。这是一个南极大陆内陆的夏天足够温暖，苔原植被生长，山区冰川由压力熔点的冰组成。在这些温和的条件下，以及随后，冰川槽的侵蚀很可能降低了冰盖表面相对于山脉的高度。这意味着轨道引起的冰厚周期性波动的范围已逐渐局限于较低的高度。
An elevated erosional trimline in the heart of West Antarctica in the Ellsworth Mountains tells of thicker ice in the past and represents an important yet ambiguous stage in the evolution of the Antarctic Ice Sheet. Here we analyse the geomorphology of massifs in the southernmost Heritage Range where the surfaces associated with the trimline are overlain by surficial deposits that have the potential to be dated through cosmogenic nuclide analysis. Analysis of 100 rock samples reveals that some clasts have been exposed on glacially moulded surfaces for 1.4 Ma and perhaps more than 3.5 Ma, while others reflect fluctuations in thickness during Quaternary glacial cycles. Modelling the age of the glacially moulded bedrock surface based on cosmogenic10Be,26Al and21Ne concentrations from a depth-profile indicates a minimum exposure age of 2.1–2.6 Ma. We conclude that the glacially eroded surfaces adjacent to the trimline predate the Last Glacial Maximum and indeed the Quaternary. Since erosion was by warm-based ice near an ice-sheet upper margin, we suggest it first occurred during the early glaciations of Antarctica before the stepped cooling of the mid-Miocene at ∼14 Ma. This was a time when the interior Antarctic continent had summers warm enough for tundra vegetation to grow and for mountain glaciers to consist of ice at the pressure melting point. During these milder conditions, and subsequently, erosion of glacial troughs is likely to have lowered the ice-sheet surface in relation to the mountains. This means that the range of orbitally induced cyclic fluctuations in ice thickness have progressively been confined to lower elevations.
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DOI：
10.5194/esurf-4-515-2016
发表时间：
2015-11
期刊：
--
影响因子：
--
作者：
M. Westoby;S. Dunning;J. Woodward;A. Hein;S. Marrero;Kate Winter;D. Sugden
通讯作者：
M. Westoby;S. Dunning;J. Woodward;A. Hein;S. Marrero;Kate Winter;D. Sugden
使用受现场证据约束的数值模型重建南极洲威德尔海海湾的末次盛冰期冰盖
影响因子：
4
作者：
Le Brocq A
通讯作者：
Le Brocq A
影响因子：
2.7
作者：
Marrero, Shasta M.;Phillips, Fred M.;Balco, Greg
通讯作者：
Balco, Greg
影响因子：
64.8
作者：
Naish, T.;Powell, R.;Williams, T.
通讯作者：
Williams, T.
埃尔斯沃思冰下高地：南极西部冰盖的形成和消退
影响因子：
4.9
作者：
Ross N
通讯作者：
Ross N