Since the Last Glacial Maximum, ∼20 k.y. ago, Alpine glaciers have retreated and thinned. This transition exposed bare bedrock surfaces that could then be eroded by a combination of debuttressing or local frost cracking and weathering. Quantification of the respective contributions of these processes is necessary to understand the links between long-term climate and erosion in mountains. Here, we quantified the erosion histories of postglacial exposed bedrock in glacial valleys. Combining optically stimulated luminescence and terrestrial cosmogenic nuclide (TCN) surface exposure dating, we estimated the erosion rate of bedrock surfaces at time scales from 10¹ to 10⁴ yr. Bedrock surfaces sampled from the flanks of the Mer de Glace (Mont Blanc massif, European Alps) revealed erosion rates that vary from 3.5 ± 1.2 ⋅ 10⁻³ mm/yr to 4.3 ± 0.6 mm/yr over ∼500 m of elevation, with a negative correlation between erosion rate and elevation. The observed spatial variation in erosion rates, and their high values, reflect morphometric (elevation and surface slope) and climatic (temperature and snow cover) controls. Furthermore, the derived erosion rates can be used to correct the timing of deglaciation based on TCN data, potentially suggesting very rapid ice thinning during the Gschnitz stadial.

中文翻译：

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冰川后的基岩表面侵蚀和冰消时间：勃朗峰地块（西阿尔卑斯山）的新见解

自大约20年前的最后一次冰川最大值以来，高山冰川已经退缩并变薄。这种过渡暴露出裸露的基岩表面，然后可能因初次发芽或局部霜冻开裂和风化而被侵蚀。为了了解长期气候与山区侵蚀之间的联系，有必要对这些过程的各自贡献进行量化。在这里，我们量化了冰川谷后冰期暴露基岩的侵蚀历史。结合光激发的发光和地球上的宇宙成因核素（TCN）表面暴露测年，我们估计了时间尺度为10 ¹到10 ⁴的基岩表面的腐蚀速率年。从Mer de Glace（勃朗峰地块，欧洲阿尔卑斯山）两侧采集的基岩表面的侵蚀速率在海拔〜500 m范围内从3.5± 1.2⋅10 ^-3 mm / yr到4.3±0.6 mm / yr不等。侵蚀率与海拔高度呈负相关。观测到的侵蚀速率及其高值的空间变化反映了形态（高度和表面坡度）和气候（温度和积雪）控制。此外，得出的侵蚀速率可用于基于TCN数据校正冰消冰的时间，这可能暗示在格施尼茨（Gschnitz）恒星期冰非常稀薄。