Deglaciation of the Marble Hills, Southern Ellsworth Mountains

该奖项支持了一个项目，该项目迄今为止收集了一系列样品，这些样品是在埃尔斯沃思山脉南端的大理石山进行侦察实地工作时收集的，在那里，WAIS流入Ronne- Filchner冰架的头部。这些不稳定的冰川样本覆盖了比现在的冰面高500米的海拔范围，它们大多是多面石样，这些石样是在大理石山的最高点从冰川最大值的冰撤退到现在的高度时搁浅的。这些样本将用宇宙起源的10 be测定年代，使我们能够获得这一基本上不受约束的冰盖部分的初步变薄历史。研究结果将为威德尔海地区自末次盛冰期以来WAIS的历史提供首次数值测年控制。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，这些重建主要基于缺乏年龄控制的地貌观测。这些结果将补充海洋地球物理限制，在冰川极大期将地面冰扩展到威德尔海，并沿着威德尔海北部海岸绘制冰界限和定年。大理石山的暴露年龄将与罗斯海和玛丽伯德地全新世冰川消融的时间过程重建提供有趣的比较。由于这些地区在气候、水深和河床特征上的差异，对它们的消冰历史进行比较将有助于深入了解冰盖的动力学，也许有助于解释在罗斯海及其周围的WAIS长期退缩。威德尔海也是南极底水（AABW）形成的重要地点，可能是连接南极底水与全球气候系统的重要纽带。由于威德尔海冰盖的扩张会改变AABW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.