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

点击翻译按钮获取中文摘要

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.