Programme des sessions > Recherche par auteur correspondant > Girault Igor

This presentation reports preliminary results of infra-red stimulated luminescence (IRSL) dating, electron spin resonance dating (ESR) and terrestrial cosmogenic nuclides (TCN) burial dating of fluvial deposits in the Adour basin. The Adour river today drains a 17,000 km² basin, extending on the northern side of the Pyrenees, towards the Atlantic Ocean. The Quaternary evolution of the Adour basin, as reflected in the spatial distribution of the fluvial terraces, is marked by dramatic changes in the river network resulting from the capture of its main tributaries. Five main terrace levels (T1, T2, T3, T4, T5) have been previously identified. Upstream, the main outlet river of the Lourdes ice lobe switched between the Gabas valley (T4), the Luy du Béarn valley (T3), the Adour valley (T2) and the Gave de Pau valley (T1). Downstream, the Adour river was successively captured by the Luy réunis (T3), the Gaves réunis (T2) and the Nive river (T1). Until now, these terrace levels have remained undated. Previous authors tentatively correlated each terrace level to a single glacial cycle. However, in other river basins, recent efforts at absolute dating of fluvial terraces have challenged this view. We propose a new chronology of the fluvial terraces in the Adour basin, based on eleven IRSL ages, seven ESR ages and six TCN burial ages spanning four main terrace levels (T1, T2, T3, T4). The results help us to better constrain the timing of the capture events that have shaped the Adour basin.