Deglaciation of the Marble Hills, Southern Ellsworth Mountains

该奖项支持一个项目，以确定一系列样品的日期，这些样品是在埃尔斯沃思山脉南端的大理石山进行实地考察时收集的，WAIS在那里流入伦讷-菲尔希纳冰架的头部。 这些冰川不稳定的样本覆盖了目前冰面以上500米的高度范围，大部分是刻面的，直到被搁浅的石头作为压倒性的，冰川最大的冰从大理石山的最高点撤退到现在的水平。这些样品将与宇宙成因10 Be的日期，使我们能够获得一个初步的变薄的历史，这在很大程度上不受约束的部门的冰盖。结果将提供第一个数字测年控制的历史上的韦德尔海地区的WAIS自末次冰期以来的最大。这一新数据将限制埃尔斯沃思山脉冰盖的重建，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。 这些结果将补充海洋地球物理方面的制约因素，即在冰川最大期期间，地面冰向威德尔海的扩展，以及威德尔海北方沿着冰限的测绘和测年。从大理石山暴露年龄将提供一个有趣的比较与重建的时间过程中全新世冰消作用在罗斯海和玛丽伯德土地。由于这些地区之间的气候，水深和床特征的差异，比较它们的冰川消退历史将提供深入了解冰盖的动态，也许有助于解释长期WAIS撤退罗斯海及其周围。威德尔海也是南极底层水（AABW）形成的重要场所，它可能是连接WAIS和全球气候系统的重要纽带。由于威德尔海冰盖的扩张会改变AABW的分布，因此了解冰川消退的时间对于了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.