Environmental and climate reconstruction of the late-glacial-Holocene transition from a lake sediment sequence in Aubrac, French Massif Central: Chironomid and diatom evidence

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Gandouin, Emmanuel, Rioual, Patrick, Paillès, Christine, Brooks, Stephen J., Ponel, Philippe, Guiter, F., Djamali, Morteza, Birks, H. John, B., Andrieu-Ponel, Valérie, Leydet, Michelle, Belkacem, Dahvya, Haas, Jean Nicolas, van Der Putten, Nathalie, de Beaulieu, Jacques-Louis
• Other Authors: Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement IRD : UMR237-Centre National de la Recherche Scientifique (CNRS), Institute of Geology and Geophysics Beijing (IGG), Chinese Academy of Sciences Beijing (CAS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences Bergen (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), University College of London London (UCL), Institute of Botany Innsbruck, Universität Innsbruck Innsbruck, Skane University Hospital Lund
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Subfossil insects; Temperature reconstruction; Past aquatic ecosystem; Western Europe; Palaeolimnology; Corynocera ambigua; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Arctic
• Online Access: https://hal.science/hal-01444637; https://hal.science/hal-01444637/document; https://hal.science/hal-01444637/file/17_Gandouin%20et%20al%202016-HAL.pdf; https://doi.org/10.1016/j.palaeo.2016.08.039

International audience The analysis of fossil chironomid and diatom assemblages from a sedimentary record from Les Roustières peat bog (Massif Central, France, 1196 m asl) allows the reconstruction of past environmental and climate changes during the late-glacial and early Holocene. Chironomid assemblages showed that the infilling of the palaeolake had commenced during the Oldest Dryas (GS-2b) as suggested by the rapid decrease in chironomid species associated with the cold and deep zone of lakes and by their replacement by littoral and eutrophic taxa. Quantitative July temperature reconstructions, based on the chironomid data, suggest that mean July air temperature (Tjul) ranged between 6 °C and 11 °C at the termination of the Oldest Dryas period (GS-2b). Climate began to warm at the start of the Bølling period (GI-1e), between 15,000 and 14,800 cal yr BP, with a rise in Tjul of about 4 °C. This climate warming is contemporaneous with lake eutrophication as suggested by diatoms and chironomids. Maximum temperatures of 13–14 °C were reached around 13,600 cal yr BP during the Allerød period (GI-1c–GI-1a). The Younger Dryas period (GS-1) is marked by a return to cold conditions with Tjul of about 10 °C during a first phase, then 13 °C in its terminal part. A probable increase in the duration of the ice-cover may have favoured arctic and alpine diatom species. The early-Holocene climate improvement is marked by a rise in Tjul of about 3 °C.