The Pyrenees: environments and landforms in the aftermath of the LGM (18.9–14.6 ka)

Magali Delmas (1) , Yanni Gunnell (2) , Marc Calvet (1) , Théo Reixach (1) , Marc Oliva (3)

1 HNHP - Histoire naturelle de l'Homme préhistorique
2 EVS - Environnement, Ville, Société
3 University of Barcelona

In the Pyrenees, the magnitude of ice fluctuations during the earlier part of the last glacial-to-interglacial transition (18.9–14.6 ka), or LGIT, is only well established for a dozen of small catchments, mostly on the basis of exposure ages. Constraints on the distribution and chronology of early LGIT glaciers in the eastern massifs have been used as proxies for palaeoclimatic reconstructions, with widespread evidence of rapid and extensive post-LGM deglaciation. In some Pyrenean valleys, such as in the upper Têt catchment, the LGM equilibrium-line altitude (ELA) rose from 2000–2100 m to ~2400 m as early as 19–20 cal ka BP. Thereafter, two glacier stillstands occurred around 19–18 ka and 17–16 ka. Glaciation patterns reveal systematically lower ELAs and higher glacier mass-balance gradients among massifs on the northern side of the range (thereby indicating cooler and wetter conditions) than on its southern side. These N–S climatic contrasts, still prominent today, have thus prevailed since the end of the LGM. In the central and western Pyrenees, data for the Noguera Ribagorçana, Noguera de Tor and Gállego valleys also document glaciers confined to the upper catchments around 17–16 ka.

Mots clés: Last glacial-to-interglacial transition; Stadial moraine; Terrestrial cosmogenic nuclide exposure dating; Climatic gradient; Pyrenees

Domaines: Géomorphologie

Magali Delmas, Yanni Gunnell, Marc Calvet, Théo Reixach, Marc Oliva. The Pyrenees: environments and landforms in the aftermath of the LGM (18.9–14.6 ka). European Glacial Landscapes, Elsevier, pp.185-200, 2023, 978-0-323-91899-2. ⟨10.1016/B978-0-323-91899-2.00040-1⟩. ⟨hal-03989968⟩