Lithological control on the post-orogenic topography and erosion history of the Pyrenees

Numerous studies on active mountain ranges have demonstrated the interaction between tectonics and climate in shaping topography. Here we explore how variations in rock types have affected the topographic development of the Pyrenees since cessation of orogenesis ca. 20 Ma. Our study is based on a multidisciplinary approach and integrates topographic analyses, rock strength measurements and thermal modelling of low-temperature thermochronological data published across the Central Pyrenees. Results indicate a strong influence of rock strength in determining the post-orogenic morphology of the Pyrenees. We observe a correlation between rock strength and the normalized channel steepness index (k(sn)) of the different lithologies. Moreover, the highest topography is dominated by the Variscan plutonic massifs which have highest rock strength. Consequently, the drainage divide appears to track the position of these massifs. Abrupt deceleration of exhumation recorded in inverse modelling of low-temperature thermochronologic data suggests that the exhumation of the Variscan massifs also played role in lowering in erosion rates over the massifs during orogenesis. Crown Copyright (C) 2019 Published by Elsevier B.V. All rights reserved.