Significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on Alpine limestone cliffs (Reintal, German Alps)
Significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on Alpine limestone cliffs (Reintal, German Alps)
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落石强度和碳酸盐溶解对高山石灰岩悬崖岩石坡度侵蚀和地貌工作的意义（德国阿尔卑斯山雷因塔尔）
DOI：
10.1016/j.geomorph.2012.04.007
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发表时间：
2012
期刊：
影响因子：
3.9
通讯作者：
D. Morche
中科院分区：
文献类型：
--
作者：
M. Krautblatter;M. Moser;L. Schrott;J. Wolf;D. Morche
在高寒和北极环境中，低、中、高震级岩质边坡破坏的比例贡献协调了岩质边坡侵蚀和岩崩灾害。在这项研究中，我们比较了在陡峭的阿尔卑斯Reintal槽谷中碳酸盐溶解的产沙量、地貌工作和岩壁退缩以及五种不同程度的岩质边坡破坏。我们结合了四年的岩崩收集测量140Mg碎片岩崩，20世纪的中型岩崩科学记录以及碳定年和15至19世纪岩石雪崩活动的历史记录。总岩崩产沙量8.6（±3.4）∗103m3 - 1年−1，主要是高震级的岩崩（bbb106m3: 62%）和低震级的碎屑落（<10m3: 18%），而中等震级的巨石、块体和悬崖落则不太重要。震级信号与硅质岩石的研究相矛盾，硅质岩石的中等震级岩崩主要是岩石边坡侵蚀。岩崩（123（±47）Wkm−2，即0.38（±0.15）mmyear−1）和溶质运移（34（±18）Wkm−2，即0.05（±0.03）mmyear−1）在17.3km2大流域释放的地貌作用超过了先前公布的高山值一个到多个数量级。我们假设小震级和高震级岩崩增强的震级信号是碳酸盐悬崖的特征。孔隙度的增加对破碎的敏感性和沿潜在滑动面持续的碳酸盐溶解可能有利于低震级和高震级岩质边坡的破坏。在这里，我们展示了岩质边坡破坏的震级信号如何影响岩壁退缩、地貌工作、岩崩沉积和沉积物连通性。
The proportional contribution of low-, mid- and high magnitude rock slope failure orchestrates rock slope erosion and rockfall hazard in Alpine and Arctic environments. In this study, we compare sediment yield, geomorphic work and rock wall retreat of carbonate dissolution and five different magnitudes of rock slope failure in the steep Alpine Reintal trough valley. We combine a four-year rockfall collector measurement of 140Mg of fragmental rockfall, a 20th century scientific record of mid-magnitude rockfall as well as carbon-dating and a historical record of 15th to 19th century rock avalanche activity. The total rockfall sediment yield of 8.6 (±3.4)∗103m3year−1is dominated by high-magnitude rock avalanches (>106m3: 62%) and low-magnitude debris falls (<10m3: 18%), while mid-magnitude boulder, block and cliff falls are less important. The magnitude signal contradicts studies on siliceous rocks where mid-magnitude rockfall dominates rock slope erosion. The geomorphic work released in the 17.3km2large catchment by rockfalls (123 (±47) Wkm−2, i.e. 0.38 (±0.15) mmyear−1) and solute transport (34 (±18) Wkm−2, i.e. 0.05 (±0.03) mmyear−1) exceeds previously published Alpine values by one to multiple orders of magnitude. We hypothesise that the magnitude signal of enhanced small and high magnitude rockfall is characteristic for carbonate cliffs. The elevated porosity-related susceptibility to fragmentation and persistent carbonate dissolution along potential sliding planes are likely to favour both low- and high-magnitude rock slope failures. Here we show how the magnitude signal of rock slope failure influences rock wall retreat, geomorphic work, rockfall deposition and sediment connectivity.