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Alpine topography in the light of tectonic uplift and glaciation

机译：从构造隆起和冰川作用看高山地形

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In steady-state orogens, topographic gradients are expected to increase with elevation whereas the European Alps feature a transition from increasing to decreasing slopes. This peculiar pattern has been interpreted to reflect either the critical slope stability angle or a premature fluvial landscape but is also consistent with the glacial buzz-saw hypothesis. To disentangle the contributions of each of these principles we split the Alps into contiguous domains of structural units and analyze their slope-elevation distributions emphasizing glaciated and non-glaciated realms. In comparable structural units within the extent of the last glacial maximum (LGM) the transition from increasing to decreasing slopes is located at the equilibrium line altitude (ELA) of the LGM and we interpret this to be evidence for the impact of glacial erosion. Decay rates of glacial landforms towards steady-state slopes depend on lithological properties leading to a landscape characterized by different transient states. Beyond the LGM limits the slope-elevation distributions show local maxima as well, but these are located at varying altitudes implying a tectonic driver. This observation and data from surrounding basins suggests that at least parts of the European Alps experienced a pre-Pleistocene pulse of tectonic uplift. The resulting presence of premature low-gradient terrain above the ELA during the global cooling in Plio-Pleistocene times would have heavily influenced the onset and the extent of an alpine ice cap. (C) 2015 Elsevier B.V. All rights reserved.
机译：在稳态造山带中，地形梯度预计会随着海拔的升高而增加，而欧洲阿尔卑斯山则具有从增加到减少的过渡。这种奇特的模式已被解释为反映了临界边坡稳定角或过早的河流景观，但也与冰川动锯假说相符。为了弄清每个原则的贡献，我们将阿尔卑斯山划分为结构单元的连续区域，并分析了它们的坡度-高程分布，重点是冰川和非冰川领域。在最后一次冰川最大值（LGM）范围内的可比较结构单元中，从增加的坡度到减少的坡度的过渡位于LGM的平衡线高度（ELA），我们认为这是冰川侵蚀影响的证据。冰川地貌向稳态斜坡的衰减率取决于岩性，从而形成以不同瞬态为特征的景观。超出LGM限制，坡度-高程分布也显示局部最大值，但是它们位于不同的高度，这意味着构造驱动力。来自周围盆地的观测和数据表明，至少欧洲阿尔卑斯山的部分地区经历了更新世前的构造隆升脉冲。在上新世时期全球冷却期间，在ELA上方出现的低坡度过早出现的地形将严重影响高山冰盖的形成和程度。 （C）2015 Elsevier B.V.保留所有权利。

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