Collaborative Research: Late Quaternary History of Reedy Glacier

海洋西南极冰盖（WAIS）的稳定性仍然是一个重要的，未解决的问题，预测未来的海平面变化。最近的研究表明，今天冰盖的质量平衡可能是负的或正的。这种明显的差异可能部分源于流量的短期波动。相比之下，地质观测提供了更长时间尺度上的行为证据。最近的工作涉及冰川地质测绘，测年和冰穿透雷达调查表明，冰消的罗斯海海湾和沿海玛丽伯德土地持续到晚全新世，并留下了持续的冰消和接地线撤退的可能性。然而，以前在罗斯海海湾的工作是基于来自三个地点的数据，这些地点都远离目前的接地线。需要更多来自罗斯海海湾更南部的数据来调查经济衰退是否已经结束，或者从我们以前的研究中推断出的冰川消退的速度和模式是否仍然适用于目前的接地线。该奖项提供支持，以重建Reedy冰川的演变，在南部跨南极山脉，自末次冰期最大（LGM）。由于里迪冰川从接地线以上的山脉中出现，它的表面坡度和海拔应该记录了罗斯海迄今为止接地冰厚度的变化。因此，Reedy冰川的冰川消退年表可以表明WAIS的全新世退缩是否在数千年前结束，或者现在仍在继续。这个综合的冰川学、冰川地质学和宇宙成因同位素暴露测年项目将重建里迪冰川过去的水平。在两个野外季节中，将沿着沿着冰川的长度在不同的地点绘制冰碛的地图，确定年代并进行对比。将进行雷达和全球定位系统测量，以补充现有的冰厚和速度数据，这些数据是冰川动力学模型所需的投入。该模型将用于将地质测量与下游接地线位置联系起来。最终，该研究的绘图，测年和冰建模组件将被整合到一个重建中，该重建定义了自LGM以来罗斯海南部冰厚度的变化，并将这些变化与接地线撤退的历史联系起来。这项工作直接涉及西南极冰盖倡议的关键目标，即了解西南极冰盖的动态，最近的历史和未来可能的行为。

The stability of the marine West Antarctic Ice Sheet (WAIS) remains an important, unresolved problem for predicting future sea level change. Recent studies indicate that the mass balance of the ice sheet today may be negative or positive. The apparent differences may stem in part from short-term fluctuations in flow. By comparison, geologic observations provide evidence of behavior over much longer time scales. Recent work involving glacial-geologic mapping, dating and ice-penetrating radar surveys suggests that deglaciation of both the Ross Sea Embayment and coastal Marie Byrd Land continued into the late Holocene, and leaves open the possibility of ongoing deglaciation and grounding-line retreat. However, previous work in the Ross Sea Embayment was based on data from just three locations that are all far to the north of the present grounding line. Additional data from farther south in the Ross Sea Embayment are needed to investigate whether recession has ended, or if the rate and pattern of deglaciation inferred from our previous study still apply to the present grounding line. This award provides support to reconstruct the evolution of Reedy Glacier, in the southern Transantarctic Mountains, since the Last Glacial Maximum (LGM). Because Reedy Glacier emerges from the mountains above the grounding line, its surface slope and elevation should record changes in thickness of grounded ice in the Ross Sea up to the present day. The deglaciation chronology of Reedy Glacier therefore can indicate whether Holocene retreat of the WAIS ended thousands of years ago, or is still continuing at present. This integrated glaciologic, glacial-geologic, and cosmogenic-isotope exposure- dating project will reconstruct past levels of Reedy Glacier. Over two field seasons, moraines will be mapped, dated and correlated at sites along the length of the glacier. Radar and GPS measurements will be made to supplement existing ice thickness and velocity data, which are needed as input for a model of glacier dynamics. The model will be used to relate geologic measurements to the grounding-line position downstream. Ultimately, the mapping, dating and ice-modeling components of the study will be integrated into a reconstruction that defines changes in ice thickness in the southern Ross Sea since the LGM, and relates these changes to the history of grounding-line retreat. This work directly addresses key goals of the West Antarctic Ice Sheet Initiative, which are to understand the dynamics, recent history and possible future behavior of the West Antarctic Ice Sheet.