Collaborative Research: Late Quaternary History of Reedy Glacier

海洋南极西部冰盖（WAIS）的稳定性仍然是预测未来海平面变化的一个重要的、未解决的问题。最近的研究表明，今天冰盖的物质平衡可能是负的，也可能是正的。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的时间尺度上的行为证据。最近的冰川地质测绘、年代测定和破冰雷达调查表明，罗斯海海湾和沿海的玛丽伯德地的冰川消融一直持续到全新世晚期，并留下了持续的冰川消融和基准线退缩的可能性。然而，之前在罗斯海海湾的工作是基于三个地点的数据，这些地点都远在目前的接地线以北。要调查衰退是否已经结束，或者从我们以前的研究中推断出的冰川消融的速度和模式是否仍然适用于目前的基准线，还需要来自罗斯海海湾更南边的额外数据。该奖项为重建南极横贯山脉南部芦苇冰川自末次盛冰期（LGM）以来的演变提供了支持。因为芦苇冰川出现在接地线以上的山脉，它的表面坡度和海拔应该记录罗斯海接地冰厚度的变化，直到今天。因此芦苇冰川的脱冰年代学可以表明WAIS的全新世退缩是在几千年前就结束了，还是现在还在继续。这个综合冰川学、冰川地质和宇宙成因同位素暴露测年项目将重建芦苇冰川过去的水平。在两个季节的野外考察中，将绘制冰碛地图，确定时间，并在冰川长度沿线的地点进行对比。将进行雷达和GPS测量，以补充现有的冰厚和速度数据，这些数据需要作为冰川动力学模型的输入。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，该研究的制图、测年和冰模型组成部分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，并将这些变化与基准线退缩的历史联系起来。这项工作直接解决了南极西部冰盖倡议的关键目标，即了解南极西部冰盖的动态、近期历史和可能的未来行为。

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.