Collaborative Research: Late Quaternary History of Reedy Glacier

海洋西南极冰盖(WAIS)的稳定性仍然是预测未来海平面变化的一个重要而悬而未决的问题。最近的研究表明，今天冰盖的质量平衡可能是负的，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，地质观察提供了更长时间尺度上的行为证据。最近涉及冰川地质测绘、测年和穿冰雷达调查的工作表明，罗斯湾和沿海的玛丽·伯德陆地的冰川消融一直持续到全新世晚期，留下了持续消融冰川和基准线后退的可能性。然而，之前在罗斯湾的工作是基于只有三个地点的数据，这三个地点都在目前接地线以北很远的地方。需要从罗斯海海湾更南边的地方获得更多数据，以调查衰退是否已经结束，或者从我们之前的研究中推断的冰川消融速度和模式是否仍然适用于目前的基准线。该奖项支持重建横贯北极山脉南部的芦苇冰川自末次冰盛期(LGM)以来的演变。由于芦苇冰川出现在接地线上方的山脉中，其表面坡度和海拔高度应该记录了罗斯海至今地面冰厚度的变化。因此，芦迪冰川的冰川消融年代学可以表明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年代测定项目将重建芦苇冰川的过去水平。在两个野外季节，冰川将在冰川长度沿线的地点进行测绘、日期测定和对比。将进行雷达和GPS测量，以补充现有的冰层厚度和速度数据，这些数据是冰川动力学模型所需的输入。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，这项研究的测绘、测年和冰建模部分将被整合到一项重建中，该重建定义了自末次盛冰期以来罗斯海南部冰层厚度的变化，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主要目标，即了解西南极冰盖的动态、近期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.