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Debris flow-dominated and rockfall-dominated talus slopes: Genetic models derived from GPR measurements

机译：泥石流为主和碎石为主的距骨坡度：从GPR测量得出的遗传模型

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Stratified talus deposits are reported from many different mountain environments. Numerous possible explanations are discussed in the literature; however, the sediment stores are rarely accessible as exposures are sparse. We applied ground-penetrating radar (25, 50 and 100 MHz antennae) to gain insight into the internal sediment structures of 23 alpine scree slopes; ten examples are presented in this paper. The study areas are spread over the Eastern European Alps at altitudes ranging from 1500 to 2900 m. The bedrock type is primarily limestone and dolostone; one area is composed of gneiss and mica-schist. GPR turned out to be highly suitable for investigating sediment structures of dry talus debris. The results showed that almost all of the deposits investigated are characterized by pronounced stratification. Several different types of layering were identified. Discordant layers which are restricted to confined parts of the talus are probably related to sediment redistribution processes like surficial debris flows or dry grain flows. These features frequently occur at the uppermost part of the slope caused by overland flow from the adjacent rock face, but may also develop in the downhill part of a talus. One talus in the Reintal area showed surface-parallel, persistent layers of different grain sizes which cannot be explained by any known models. We suggest a novel model of talus development which is driven by climatic fluctuations. In periods of enhanced freeze-thaw activity like the Little Ice Age, the delivery of coarse debris prevails. In warmer climate with a higher frequency of rainstorms, the depletion of finer-grained intermediate stores in less inclined rockwall positions leads to delivery of clasts smaller than 2 cm. The type of layering found within a talus is determined by rockwall parameters like height, steepness, topography and dissection of the rock face. The "storage depletion" model applies to high rockwalls with a considerable volume of intermediate storage.
机译：据报许多不同的山区环境都有分层的距骨沉积物。文献中讨论了许多可能的解释。然而，由于暴露量很少，因此沉积物存储很少。我们应用了探地雷达（25、50和100 MHz天线）来深入了解23个高山碎石坡的内部沉积物结构。本文提出了十个例子。研究区域分布在东欧阿尔卑斯山，海拔从1500到2900 m。基岩类型主要是石灰岩和白云岩。一个地区是由片麻岩和云母片岩组成。事实证明，GPR非常适合用于调查干燥距骨碎片的沉积物结构。结果表明，几乎所有调查的矿床都具有明显的分层特征。确定了几种不同类型的分层。限制在距骨狭窄部位的不协调层可能与沉积物的再分配过程有关，例如表面的泥石流或干粮流。这些特征经常出现在斜坡的最上部，该斜坡是由相邻岩面的陆上流引起的，但也可能在距骨的下坡部分发展。 Reintal地区的一个距骨显示出不同粒度的表面平行且持久的层，这无法通过任何已知模型进行解释。我们建议一种由气候波动驱动的距骨发育的新模型。在诸如小冰河世纪之类的冻融活动增强的时期，通常会输送粗碎屑。在温暖的气候中，暴雨的频率较高，在倾斜度较小的岩壁位置中，较细粒度的中间存储层的耗尽导致了小于2厘米的碎屑的输送。在距骨中发现的分层类型取决于岩壁参数，例如高度，陡度，地形和岩面的解剖。 “存储耗竭”模型适用于具有大量中间存储量的高岩壁。

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