Glacier thinning and retreat drives initial acceleration of glacier sliding and erosion, de-buttressing of steep valley walls, and destabilization of ice-marginal deposits and bedrock, which can lead to massive rock avalanching and accelerated incision of tributary watersheds. A compelling example of these changes occurred in Taan Fjord in SE Alaska due to the rapid thinning and retreat of Tyndall Glacier over the past half century. Increased glacier sliding speeds led to both increased rates of subglacial erosion and the evacuation of subglacially stored sediments into the proglacial basins. The shrinking glacier also exposed proglacial tributary watersheds to rapid incision and denudation driven by >350 m of baselevel fall in a few decades. Moreover, in October 2015 a large tsunamigenic landslide occurred at the terminus of Tyndall Glacier, largely due to thinning exposing oversteepened, unstable slopes. Sediment yields from the glacier, the landslide and the tributary watersheds, measured from surveys of the sediments in the fjord collected in 1999 and 2016, are compared to ongoing changes in glacier and fjord geometry to investigate the magnitude of glacial and paraglacial denudation in Taan Fjord during retreat. In the last 50 years, sediment yields from the glacier and non-glacial tributaries kept pace with the rapid rate of retreat, and were on par with each other. Notably, basin-averaged erosion rates from the paraglacial landscape were twice that from the glacier, averaging 58 ± 9 and 26 ± 5 mm a−1, respectively. The sharp increases in sediment yields during retreat observed from both the glacier and the adjacent watersheds, including the landslide, highlight the rapid evolution of landscapes undergoing glacier shrinkage.

中文翻译：

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冰川和冰川旁剥蚀对快速冰川退缩反应的比较

冰川变薄和退缩导致冰川滑动和侵蚀的初始加速，陡峭的谷壁去支撑，以及冰缘沉积物和基岩的不稳定，这可能导致大规模的岩石崩塌和支流流域的加速切割。由于廷德尔冰川在过去半个世纪中迅速变薄和退缩，这些变化的一个引人注目的例子发生在阿拉斯加东南部的坦恩峡湾。冰川滑动速度的增加导致冰下侵蚀率的增加和冰下储存的沉积物疏散到前冰期盆地中。萎缩的冰川还使前冰期支流流域在几十年内遭受超过 350 m 的基线下降所驱动的快速切割和剥蚀。此外，2015 年 10 月，廷德尔冰川的终点发生了一次大型海啸滑坡，主要是由于变薄暴露了过度陡峭、不稳定的斜坡。从 1999 年和 2016 年收集的峡湾沉积物调查中测得的冰川、滑坡和支流流域的沉积物产量与冰川和峡湾几何形状的持续变化进行比较，以研究塔安峡湾的冰川和冰旁剥蚀程度撤退期间。在过去的 50 年里，冰川和非冰川支流的沉积物产量与快速撤退的速度保持同步，并且彼此相当。值得注意的是，冰川旁景观的盆地平均侵蚀率是冰川的两倍，平均为 58 ± 9 和 26 ± 5 mm a 通过对 1999 年和 2016 年收集的峡湾沉积物的调查测量，将其与冰川和峡湾几何形状的持续变化进行比较，以研究退缩期间 Taan 峡湾的冰川和冰川旁剥蚀程度。在过去的 50 年里，冰川和非冰川支流的沉积物产量与快速退缩的速度保持同步，并且彼此相当。值得注意的是，冰川旁景观的盆地平均侵蚀率是冰川的两倍，平均为 58 ± 9 和 26 ± 5 mm a 通过对 1999 年和 2016 年收集的峡湾沉积物的调查测量，将其与冰川和峡湾几何形状的持续变化进行比较，以研究退缩期间 Taan 峡湾的冰川和冰川旁剥蚀程度。在过去的 50 年里，冰川和非冰川支流的沉积物产量与快速退缩的速度保持同步，并且彼此相当。值得注意的是，冰川旁景观的盆地平均侵蚀率是冰川的两倍，平均为 58 ± 9 和 26 ± 5 mm a 并且彼此相提并论。值得注意的是，冰川旁景观的盆地平均侵蚀率是冰川的两倍，平均为 58 ± 9 和 26 ± 5 mm a 并且彼此相提并论。值得注意的是，冰川旁景观的盆地平均侵蚀率是冰川的两倍，平均为 58 ± 9 和 26 ± 5 mm a-1， 分别。从冰川和邻近分水岭（包括滑坡）观察到的撤退期间沉积物产量的急剧增加，突显了冰川收缩景观的快速演变。