Constraining erosion rates and patterns for glaciated basins in the European Alps using thermoluminescence thermochronology

Rates and patterns of erosion by glaciers and their contribution to the evolution of tectonically active mountain topographies remain poorly understood. Insights from apatite fission track and (U-Th)/He thermochronometry have been restricted by minimum detectable cooling ages measured in millions of years that are relevant to the exhumation of bedrock from depths of upwards of c. 2 km, whilst cosmogenic nuclide concentration methods reveal the timing of removal of only the uppermost 2 m of bedrock, which is relatively superficial in glacial erosion terms. We have therefore applied the relatively new technique of K-feldspar thermoluminescence thermochronometry (Brown & Rhodes, 2022) that is capable of resolving near-surface cooling histories of bedrock over timescales spanning the most recent glacial-interglacial cycle. This very low-temperature thermochronometer permits analysis of exhumation from depths of several hundred metres upwards and is therefore sensitive to the erosion processes of specific components of the glacier system as well as the dynamism and significance of major erosional landforms. Results are presented from two currently glaciated valleys in the central European Alps that possess contrasting features and longitudinal valley profiles, and these suggest the ability to better understand glacial process contributions to mountain geomorphic development and to improve glacial erosion laws commonly used in numerical landscape evolution models.