Late Quaternary chronology of the Allier terrace sediments (Massif Central, France)

Abstract

The Late Quaternary terrace chronology of the middle Allier basin (Limagne, Massif Central, France) has been reconstructed by means of terrace (chemo)lithostratigraphy and with Th/U disequilibrium and 14C datings. The 25 m terrace level (Wb) has a Late Saalian age. The Weichselian Terrace levels Xa and Xb (20 and 10 m) contain at least four different lithostratigraphical units: one Middle Pleniglacial, two Late Pleniglacial and one Younger Dryas. The oldest Holocene ZY terrace sediments have Atlanticum ages. Timing of Allier incision and sedimentation during the Late Pleniglacial and Late Glacial appears to be mainly climate-related. Major fluvioglacial sediment fluxes from melting glaciers on the Mt. Dore and Cantal at the end of the Late Pleniglacial caused a strong rise of the Allier river bed level. This rise of approximately 20 m in the Limagne seems to have contributed to the formation of lakes like Marais de Ravel and the Grand Marais. Fluvial dynamics in the Allier basin seem to be mainly climate controlled.