| Summary: | International audience Deep-sea and terrestrial records allow to document the amplitude, timing and duration of the oceanic and vegetation responses to orbital and millennial-scale changes, in particular during North Atlantic cooling events (Heinrich events, HEs) in Western Europe during the Last Glacial Period (~115- 27 ka).We propose a multiproxy study based on two deep-sea cores retrieved in the Bay of Biscay (MD04-2845) and the Gulf of Lion (MD99-2343) to reconstruct vegetation and climatic changes in southwestern and southeastern France during Heinrich stadials 4, 5 and 6. These records are well chronologically constrained by numerical dating (new IRSL ages for the MD04-2845 deep-sea core) and new age-depth models, based on Bayesian statistics and stratigraphic constrains using ChronoModel software and ArchaeoPhases R-package. The comparison of both deep-sea cores with other terrestrial and marine records from NE Atlantic and NW Mediterranean regions show different magnitudes in the semi-desert expansions following Heinrich Stadials (HS, 4, 5 and 6) in Western Europe. Although in southwestern France, the development of the semi-desert is more pronounced during HS6 compared to HS 4 and 5, in the southeast, this stadial is marked by forest development. These contrasted responses during these events appear to be the result of different intensities of the thermohaline circulation and local oceanic processes associated with the instability of the Laurentian ice sheet.
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