Many of the valleys on the southern slope of the Alps are over-deepened, having bedrock valley floors well below sea level. This has typically been attributed to incision that occurred during the Messinian Salinity Crisis (MSC) when sea level dropped by hundreds of meters, leading to incision of many of the margins of the Mediterranean. We reassess this interpretation by documenting the correct elevation of the valley floor of the Adige river, one of the major valleys draining the Southern Alps, and by estimating the vertical motion of that valley floor since the end of Messinian incision. We re-evaluated the bedrock incision in the Adige valley using existing borehole data and seismic profiles. We estimate the vertical post-Messinian uplift using thermochronometric data that reveal the removed rock mass and then infer the expected isostatic uplift. These data are combined to reconstruct paleo-river gradients and to test viability of incision profiles. We find that the erosive surfaces in the drill holes restore to a paleo-elevation well below estimates of the Messinian Salinity Crisis (MSC) sea level. Restored valley gradients are often reversed compared to todays river gradients, as the uplift correction is higher upstream. A Messinian age of the erosional unconformities within the Alps can therefore be excluded based on the current best estimates of Messinian Mediterranean sea level and post-Messinian rock uplift. Pleistocene glacial erosion left a major signature on the geomorphology of the valleys, which is documented by glacially over-deepended valleys in the northern Alps. These valleys are not influenced by the Messinian sea-level drawdown. Therefore, it is suggested that the over-deepened valleys on the southern slope of the Alps are also glacial in origin.

中文翻译：

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南阿尔卑斯山内的墨西尼或更新世山谷切口

阿尔卑斯山南坡上的许多山谷都被加深了，基岩山谷的底面远低于海平面。这通常归因于在墨西尼盐度危机（MSC）期间发生的切口，当时海平面下降了数百米，导致许多地中海边缘的切口。我们通过记录正确的阿迪杰河谷底高度（南阿尔卑斯山的主要流域之一）以及估计自墨西尼切口结束以来该谷底的垂直运动来重新评估这种解释。我们使用现有的钻孔数据和地震剖面重新评估了阿迪杰山谷的基岩切口。我们使用热年代计数据估算梅西尼亚后的垂直隆升，该数据揭示了去除的岩体，然后推断出预期的等静压隆起。这些数据被组合以重建古河梯度并测试切口轮廓的可行性。我们发现钻孔中的侵蚀性表面恢复到古高程，远低于墨西尼盐度危机（MSC）海平面的估计值。与今天的河流坡度相比，恢复的山谷坡度通常会反转，因为上游的隆升校正更高。因此，根据当前对墨西拿地中海海平面和墨​​西拿后岩石隆升的最佳估计，可以排除阿尔卑斯山内侵蚀不整合的墨西拿年龄。更新世的冰川侵蚀是山谷地貌的主要标志，阿尔卑斯山北部冰川超深的山谷记录了这一点。这些山谷不受墨西尼海平面下降的影响。因此，建议阿尔卑斯山南坡上的超深谷也起源于冰川。