Deglaciation of the Marble Hills, Southern Ellsworth Mountains

该奖项支持一个项目，以确定一系列样本的年代，这些样本是在埃尔斯沃斯山脉南端的大理石山进行一些实地勘察工作时收集的，WAIS在那里流入罗恩-菲尔什内尔冰架的顶部。这些不稳定的冰川样本覆盖在目前冰面以上500米的高度范围内，大部分都是刻面的，直到随着覆盖冰川的最大冰层从大理石山的最高点退回到现在的水平，搁浅的石头。这些样品将以宇宙成因的10Be为年代，使我们能够获得这一基本上不受限制的冰盖部分的初步变薄历史。这一结果将提供自上一次冰盛期以来韦德尔海地区WAIS历史上的第一个数字测年控制。这些新数据将限制埃尔斯沃斯山脉的冰盖重建，到目前为止，冰盖重建在很大程度上是基于缺乏年龄控制的地貌观测。这一结果将补充海洋地球物理方面对冰川盛期期间地面冰向威德尔海扩张的限制，并将补充威德尔海北部海岸冰界限的测绘和年代测定。来自大理石山的暴露年代将提供一个有趣的对比，与重建罗斯海和马里伯德岛全新世冰川消融的时间进程相比较。由于这些地区在气候、水深和河床特征上的差异，对比它们的冰川消融历史将有助于深入了解冰盖的动态，并可能有助于解释WAIS在罗斯海及其周围地区的长期撤退。威德尔海也是南极底层水(AABW)形成的重要地点，它可能是连接WAIS和全球气候系统的重要纽带。由于威德尔海的冰盖扩大会改变AABW产量的分布，因此了解冰川消融的时间对于理解当今海洋环流模式的建立非常重要。

This award supports a project to date a series of samples that were collected during some reconnaissance fieldwork in the Marble Hills, at the southern end of the Ellsworth Mountains, where the WAIS flows into the head of the Ronne- Filchner Ice Shelf. These glacial erratic samples cover a range of altitudes up to 500 m above the present ice surface and are mostly faceted till stones that were stranded as overriding, glacial-maximum ice retreated from the highest point in the Marble Hills to its present level. The samples will be dated with cosmogenic 10 Be, allowing us to obtain a preliminary thinning history for this largely unconstrained sector of the ice sheet. The results will provide the first numerical dating control on the history of the WAIS in the Weddell Sea region since the last glacial maximum. This new data will constrain ice sheet reconstructions, which up to now have been based heavily on geomorphological observations lacking age control, in the Ellsworth Mountains. The results will complement marine geophysical constraints on the expansion of grounded ice into the Weddell Sea during the glacial maximum, and mapping and dating of ice limits along the northern coasts of the Weddell Sea. The exposure ages from the Marble Hills will provide an interesting comparison with reconstructions of the time-course of Holocene deglaciation in the Ross Sea and in Marie Byrd Land. Because of differences in climate, bathymetry, and bed characteristics between these regions, comparison of their deglaciation histories will provide insight into the dynamics of the ice sheet, and perhaps help to explain the prolonged WAIS retreat in and around the Ross Sea. The Weddell Sea is also an important site of Antarctic Bottom Water (AABW) formation, and it may act as an important link between the WAIS and the global climate system. Because an expanded ice sheet in the Weddell Sea would have altered the distribution of AABW production, knowing the timing of deglaciation is important for understanding the establishment of present-day patterns of ocean circulation.