Considerable research has been focused on the syn-orogenic evolution of mountain belts in order to explore interactions between tectonic, climate and surface processes. Comparatively, limited work has been carried on the post-orogenic stage of mountain ranges. Because of the relatively small-sized of the orogen, the good quality of exposure and large volume of dataset, the Pyrenees are a natural laboratory to study orogenic processes. Moreover, the Pyrenees are characterized as a post-orogenic

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... ystem since at least 20 Ma and constitute a perfect target for this thesis. Our aim in not to solely resolve the post-orogenic history of the Pyrenees, but rather provide an understanding of fundamental behaviours and processes of the late syn- to post-orogenic systems. The purpose of this study is to better constrain the transition from crustal thickening to post-orogenic decay in mountain ranges in term of topographic and sediment flux toward foreland basins and surrounding continental margins. This is achieved through a multi-disciplinary approach combining analyses of low-temperature thermochronological data (apatite and zircon fission track, apatite helium and 4He/3He apatite data), topographic analyses from digital elevation model of the Pyrenees and landscape evolution models. Thermal histories inferred using a similar inverse modelling from pre-existing apatite and zircon fission track and apatite (U-Th)/He data document the syn-exhumation history and reveal the late syn- to post-orogenic transition in the Central Pyrenees. The main exhumation associated with the orogenic growth is diachronous in the Central Pyrenees and younging from north to south. In the Northern Pyrenean zone, the main exhumation occurred during Middle Miocene times (i.e. 40-45 Ma) whereas in the southern Axial Zone, main exhumation is recorded during Oligocene times (i.e. 30-25 Ma). Thermal histories also reveal an abrupt and diachronous cooling cessation across the Central Pyrenees. Cooling cessation, associated with the post-orogenic transit [...]