10th International Conference on Geomorphology
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Glacial-periglacial transition in the northern Central Pyrenees from the Bølling–Allerød to the Younger Dryas

Marcelo Fernandes1, Marc Oliva2, Gonçalo Vieira1,3, José María Fernández-Fernández4, David Palacios4, Julia García-Oteyza2, Josep Ventura2, and Irene Schimmelpfennig5
Marcelo Fernandes et al.
  • 1University of Lisbon, Institute of Geography and Spatial Planning, Avenidas Novas - Lisboa, Portugal (marcelo.fernandes@live.com)
  • 2Department of Geography, Universitat de Barcelona, Catalonia, Spain
  • 3Associated Laboratory Terra, Portugal
  • 4Aix‐Marseille Université, CNRS, IRD, INRAE, Coll. France, UM 34 CEREGE, Aix‐en‐Provence, France
  • 5Consortium: Georges Aumaître, Karim Keddadouche

The Upper Garonne Basin hosted the largest glacier of the Pyrenees during Late Pleistocene glaciations. Glacial retreat started after the Last Glacial Maximum (20-19 ka) of the last glacial cycle, and by the onset of the Bølling–Allerød interstadial (B-A; 15-14 ka) ice masses were already confined within the glacial cirques and highest valleys. In the Aran Valley, headwaters of the Garonne Basin, the low glacial cirques (with maximum elevations of ~2600 m) preserve a significant variety of glacial and periglacial landforms of unknown age. This study focuses in the Locampo Cirque, where we conducted a detailed geomorphological mapping of the glacial and periglacial landforms and dated a set of 8 samples using 10Be Cosmic-Ray Exposure (CRE). This approach allowed to establish the chronology and identify the mechanisms involved in the transition from glacial to periglacial dynamics. CRE ages reveal that the external moraine closing the cirque (2210-2335 m) probably formed during the second half of the B-A at 13.7 ± 1.5 ka. Subsequently, glaciers retreated, and a rock glacier developed inside the external moraine (2210-2310 m) during the paraglacial phase. The final stabilization of this rock glacier most likely occurred during the Younger Dryas (YD)-Holocene transition, at 11.9 ± 0.7 ka. These results report the first chronology on the formation of rock glaciers in the northern slope of the Central Pyrenees and confirm the pattern observed in other mid-latitude mountains, showing that the final deglaciation occurred during the (cold but dry) YD, accompanied by the development and stabilization of rock glaciers.

How to cite: Fernandes, M., Oliva, M., Vieira, G., Fernández-Fernández, J. M., Palacios, D., García-Oteyza, J., Ventura, J., and Schimmelpfennig, I.: Glacial-periglacial transition in the northern Central Pyrenees from the Bølling–Allerød to the Younger Dryas, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-614, https://doi.org/10.5194/icg2022-614, 2022.