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Paraglacial slope failures in the Aran valley (Central Pyrenees)
Quaternary International ( IF 1.9 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.quaint.2020.07.045
M. Fernandes , M. Oliva , G. Vieira

Abstract Slope failures are widespread phenomena in mid-latitude mountain environments that were glaciated during the Last Glacial Cycle. This is the case of the Aran valley, in the Upper Garonne catchment, Central Pyrenees, that included glaciers several hundred meters thick. Following postglacial warming and ice thinning, the recently deglaciated slopes were subject to intense stress readjustments - the so-called paraglacial dynamics. We have identified up to 135 major slope failures in the Aran valley, with only 10 units occurring outside the glaciated domain of the maximum ice extent of the Last Glacial. The presence of polished bedrock surfaces, till and moraine ridges next to some of these features evidence a close connection between glacial and slope processes. We have detected different types of slope failures affecting both bedrock (12 large catastrophic rock slope failures, 16 rock-slope deformation, 34 rockfalls, and 49 rockslides) and unconsolidated glacial sediments (14 slope readjustments on drift-mantled slopes). The average altitude of rock slope failures oscillates between 1551 and 1991 m, with a mean length ranging from 147 to 905 m and a width between 247 and 513 m. The affected surface is also highly variable, oscillating between 0.02 and 126.2 ha. Slope failures occur in different lithological settings, but they are most frequent in slate, lutite and limestone bedrocks. We conclude that most of the failures show a paraglacial origin, though other factors (i.e. lithology and topography) promoted slope instability.

中文翻译:

阿兰河谷(比利牛斯山脉中部)的冰河边坡崩塌

摘要 边坡失稳是末次冰期循环期间冰川作用的中纬度山区环境中普遍存在的现象。位于比利牛斯中部上加龙河流域的阿兰山谷就是这种情况,其中包括数百米厚的冰川。在冰后变暖和冰层变薄之后,最近冰川消融的斜坡受到强烈的应力调整——所谓的冰河边缘动力学。我们已经在阿兰河谷确定了多达 135 个主要的斜坡失稳,只有 10 个单位发生在末次冰川最大冰范围的冰川区域之外。抛光的基岩表面、耕地和冰碛山脊与其中一些特征相邻的存在证明了冰川和斜坡过程之间的密切联系。我们已经检测到影响基岩(12 次大型灾难性岩石斜坡破坏、16 次岩石斜坡变形、34 次落石和 49 次滑坡)和松散冰川沉积物(14 次对漂流覆盖斜坡进行斜坡调整)的不同类型的斜坡破坏。岩质边坡破坏平均海拔在1551~1991 m之间波动,平均长度147~905 m,宽度247~513 m。受影响的表面也变化很大,在 0.02 到 126.2 公顷之间波动。斜坡破坏发生在不同的岩性环境中,但最常见于板岩、黄灰岩和石灰岩基岩。我们得出的结论是,尽管其他因素(即岩性和地形)促进了斜坡的不稳定性,但大多数失败都显示出冰河缘起因。和 49 次岩石滑坡)和松散的冰川沉积物(14 次对漂流覆盖斜坡的斜坡重新调整)。岩质边坡破坏平均海拔在1551~1991 m之间波动,平均长度147~905 m,宽度247~513 m。受影响的表面也变化很大,在 0.02 到 126.2 公顷之间波动。斜坡破坏发生在不同的岩性环境中,但最常见于板岩、黄灰岩和石灰岩基岩。我们得出的结论是,尽管其他因素(即岩性和地形)促进了斜坡的不稳定性,但大多数失败都显示出冰河缘起因。和 49 次岩石滑坡)和松散的冰川沉积物(14 次对漂流覆盖斜坡的斜坡重新调整)。岩质边坡破坏平均海拔在1551~1991 m之间波动,平均长度147~905 m,宽度247~513 m。受影响的表面也变化很大,在 0.02 到 126.2 公顷之间波动。斜坡破坏发生在不同的岩性环境中,但最常见于板岩、黄灰岩和石灰岩基岩。我们得出的结论是,尽管其他因素(即岩性和地形)促进了斜坡的不稳定性,但大多数失败都显示出冰河缘起因。平均长度为 147 至 905 m,宽度为 247 至 513 m。受影响的表面也是高度可变的,在 0.02 到 126.2 公顷之间波动。斜坡破坏发生在不同的岩性环境中,但最常见于板岩、黄灰岩和石灰岩基岩。我们得出的结论是,尽管其他因素(即岩性和地形)促进了斜坡的不稳定性,但大多数失败都显示出冰河缘起因。平均长度为 147 至 905 m,宽度为 247 至 513 m。受影响的表面也变化很大,在 0.02 到 126.2 公顷之间波动。斜坡破坏发生在不同的岩性环境中,但最常见于板岩、黄灰岩和石灰岩基岩。我们得出的结论是,尽管其他因素(即岩性和地形)促进了斜坡的不稳定性,但大多数失败都显示出冰河缘起因。
更新日期:2020-11-01
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