We describe glacial-geological observations and cosmogenic-nuclide exposure ages from the vicinity of the present grounding line of Tucker Glacier, a large alpine glacier flowing from the mountains of northern Victoria Land, East Antarctica, into the outer Ross Sea. These data are relevant for constraining the extent of ice sheet expansion and retreat in the Ross Sea, and associated eustatic sea level impact, between the Last Glacial Maximum (LGM) and the present. In addition, a terrestrial geological record of ice thickness change from this region could provide evidence for or against the hypothesis that rapid eustatic sea-level rise during meltwater pulse 1A (“MWP-1A”) at 14.6 ka was in part the result of rapid, large-scale thinning or breakup of a marine-based portion of the LGM ice sheet in the outer Ross Sea. Glacial-geological observations, exposure ages on glacial deposits, and a novel application of in-situ-produced cosmogenic 14C in quartz-bearing bedrock to identify the limits of LGM ice cover in the absence of direct geomorphic evidence, show that Tucker Glacier near its present grounding line was 300 to 350 m thicker than present during the LGM and thinned steadily between 17 to 5 ka. The largest possible rapid thickness change in the time period 14 to 15 ka that could be accommodated by the exposure-age data is ∼50 m, which is a small fraction of that predicted for the western Ross Sea by model simulations of the Antarctic contribution to MWP-1A. There do exist possible scenarios in which hypothesized marine ice sheet collapse in the outer Ross Sea during MWP-1A might not be recorded by ice thickness changes at Tucker Glacier. However, our record of ice thickness changes spanning this time period is the closest such record to the outer Ross Sea that is likely to exist, and it agrees with all exposure-age deglaciation chronologies from other regions of the Ross embayment in providing no evidence for such an event.

中文翻译：

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南极洲维多利亚州北部塔克冰川 - 怀特霍尔冰川汇合处的冰川地质和宇宙成因核素暴露年龄

我们描述了塔克冰川 (Tucker Glacier) 现有接地线附近的冰川地质观测和宇宙成因核素暴露年龄，塔克冰川是一个大型高山冰川，从南极洲东部维多利亚地北部的山脉流入外罗斯海。这些数据与限制罗斯海冰盖扩张和退缩的程度以及相关的海平面影响有关，在末次冰期最大值 (LGM) 和现在之间。此外，该地区冰层厚度变化的陆地地质记录可以提供证据支持或反对以下假设：在 14.6 ka 的融水脉冲 1A（“MWP-1A”）期间，海平面快速上升部分是快速上升的结果。 ，外罗斯海 LGM 冰盖的海洋部分大规模变薄或破裂。冰川地质观测，冰川沉积物的暴露年龄，以及在没有直接地貌证据的情况下，在含石英基岩中原位产生的宇宙成因 14C 的新应用，以确定 LGM 冰盖的极限，表明塔克冰川在其目前的接地线附近是 300在 LGM 期间比现在厚 350 m，并在 17 至 5 ka 之间稳定变薄。暴露年龄数据可以适应的 14 至 15 ka 时间段内可能的最大快速厚度变化为 ~50 m，这是通过南极对南极贡献的模型模拟预测的罗斯海西部的一小部分。 MWP-1A。在 MWP-1A 期间，外罗斯海的假设海洋冰盖坍塌可能无法通过塔克冰川的冰厚度变化记录下来。然而，