Quantifying fluvial and glacial erosion using detrital thermochronology, cosmogenic nuclides and numerical modelling: a case study in the European Alps

山地景观是构造、气候和侵蚀相互作用的结果。气候变化可显著影响侵蚀，特别是如果冰川平衡线高度(ELA)发生显著变化，导致侵蚀的位置和类型发生变化(河流侵蚀与冰川侵蚀)。在这个项目中，我们将使用宇宙成因核素和热年代学，并辅之以数值模拟，以量化高山地貌在几个冰川-间冰期周期中的演变。研究区域位于瑞士阿尔卑斯山中部的阿雷山谷，自0.9 Ma以来，由于冰川作用造成的山谷切割增加了大约10倍。相关的侵蚀速率的空间变化将被量化，碎屑热年代学将应用于今天的河流和来自地表和洞穴沉积的冰川沉积物。测量的年龄分布将根据源区基岩的热年代学年龄分布进行统计解释，以估计相对侵蚀速率图。用宇宙成因核素在同一水系沉积物上测量的整个流域的剥蚀率，以及公布的洞穴沉积的古剥蚀率，可以将相对剥蚀率图转换为绝对剥蚀率。此外，碎屑的热年代学结果将用于校准数值地表过程模型。这一多方法方法将提供有关第四纪气候变化期间高山环境的景观演变(例如地貌变化)的重要信息。

Mountain landscapes result from the interplay between tectonics, climate and erosion. Climate changes can noticeably influence erosion, especially if significant variations in the equilibrium line altitude (ELA) of glaciers occur, leading to changes in the location and style of erosion (fluvial vs. glacial erosion). In this project we will use cosmogenic nuclides and thermochronology accompanied by numerical modelling to quantify the evolution of alpine landscapes over several glacial-interglacial cycles. The study area is located in the central Swiss Alps in the Aare valley, for which an approximately 10-fold increase in valley incision caused by glaciations since ~0.9 Ma has been documented. Associated spatial variations in erosion rates will be quantified with detrital thermochronology applied to present-day streams and glacial sediments from surface and cave deposits. Measured age distributions will be statistically interpreted with respect to bedrock thermochronological age distributions of the source area to estimate relative erosion rate maps. Catchment-wide denudation rates measured with cosmogenic nuclides on same stream sediments and published palaeo-denudation rates from cave deposits serve to transform relative erosion rate maps to absolute rates. Furthermore, detrital thermochronological results will be used to calibrate numerical surface process models. This multi-methodological approach will give important information about landscape evolution (e.g. relief change) of alpine settings during Quaternary climate change.