Glacial and erosional contributions to Late Quaternary uplift of the European Alps

现今地球表面的速度场包含了有关构造活动的空间模式和速率的宝贵信息。然而，在欧洲阿尔卑斯山，那里的抬升速度高达~2毫米/年，对于哪个过程驱动了观测到的抬升，没有达成共识。解释隆升的过程包括对构造缩短的均衡响应、末次冰川消融、长期侵蚀、西阿尔卑斯山板块的剥离以及地幔对流导致的岩石圈和地表偏转。在这个项目中，我们想要检验一个假设，即冰川和侵蚀过程中的时空瞬变对均衡调整有重大影响，并且它们的量化使我们能够分离与构造和/或地球动力学过程有关的隆起。现场观测表明，在上一次冰川周期中，阿尔卑斯山冰盖迅速膨胀和收缩，并对先前假定的均衡平衡的有效性提出了质疑。此外，在阿尔卑斯山过深的山谷和周围的湖盆中，沉积物的圈闭导致了对侵蚀的均衡响应的瞬变。因此，我们将在包括侵蚀过程的最后一个冰川周期中使用瞬变数值冰流模拟，并根据现场观测进行校准，以估计地表加载和卸载。我们将把模型结果与新的岩石圈模型结合起来使用，这些模型来自AlpArray数据，以预测地表过程引起的岩石抬升速率。模拟的岩石抬升与观测到的岩石抬升的比较将澄清冰川作用和侵蚀在今天阿尔卑斯山抬升中的作用，并允许剩余抬升与构造和/或地球动力学过程联系起来。此外，我们将把我们的结果提升到更长的时期，例如中更新世以来，以评估第四纪冰川侵蚀对阿尔卑斯山岩石抬升和折返的综合影响。我们的模拟方法建立在SPP第一阶段的结果基础上，并将提供关键的限制，将现代和第四纪岩石隆起的空间模式与深层过程联系起来。

The present-day velocity field of the Earth’s surface holds valuable information about the spatial patterns and rates of tectonic activity. However, in the European Alps, which are uplifting at rates of up to ~2 mm/yr, no consensus exists on which processes drive the observed uplift. The processes suggested to account for uplift include isostatic response to tectonic shortening, the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as well as lithospheric and surface deflection due to mantle convection. In this project, we want to test the hypothesis that spatiotemporal transients in glaciation and erosion have a significant influence on isostatic adjustments and that their quantification allows us to isolate the uplift related to tectonic and/or geodynamic processes. Field observations suggest rapid expansion and shrinkage of the Alpine ice cap during the last glacial cycle, and cast doubt on the validity of previously assumed isostatic equilibrium. Furthermore, trapping of sediments in overdeepened valleys of the Alps and in peripheral lake basins induces transients in the isostatic response to erosion. We will therefore employ transient numerical ice flow modeling during the last glacial cycle that includes erosion processes, calibrated to field observations, to estimate surface loading and unloading. We will use the model results in conjunction with new lithospheric models, derived from AlpArray data, to predict rock uplift rates due to surface processes. Comparison of modeled with observed rock uplift will clarify the role of glaciation and erosion in the present-day uplift of the Alps, and allow residual uplift to be linked to tectonic and/or geodynamic processes. Furthermore, we will upscale our results to longer periods, e.g., since the mid-Pleistocene transition, to estimate the integrated effect of Quaternary glacial erosion on rock uplift and exhumation in the Alps. Our modeling approach builds on results from the first phase of the SPP and will provide key constraints for linking spatial patterns of present-day to Quaternary rock uplift to deep-seated processes.