Earthworn calcite granules, a nex proxy for the reconstruction of Last glacial palaeoclimate in European loess sequences : application to the study of human-environment interactions in Palaeolithic

• Main Author: Prud'Homme, Charlotte
• Other Authors: Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Panthéon-Sorbonne - Paris I, Pierre Antoine, Christophe Lecuyer
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2017
• Subjects: Loess sequences; Last Glacial; Fossil granules of calcite; Granule de calcite de vers de terre; Séquences loessiques européennes; Dernier glaciaire; Isotope stable; Paléoclimat; [SHS.GEO]Humanities and Social Sciences/Geography; Arctic; Tundra
• Online Access: https://theses.hal.science/tel-04043145; https://theses.hal.science/tel-04043145/document; https://theses.hal.science/tel-04043145/file/PRUDHOMME.pdf

Recent studies highlighted the extreme sensitivity of western European loess sequences to the millennial climatic variations that characterize the Last Glacial. Fossil granules of calcite have been identified in this sequence. They are very abundant in palaeosols. These granules produced by earthworms are composed of rhomboedric calcite crystals, organized in a radial crystalline structure. In this context, the main objective of my PhD thesis is to develop an innovative approach to characterize millennial climatic variations recorded in the loess sequences contemporaneous with the human occupations of the recent Middle Palaeolithic and the Upper Palaeolithic. The granule and mollusc concentration variations suggest warmer climate conditions during the formation of tundra gley: and boreal and arctic brown soils with the development of biodiversity (biological activity and densification of vegetation cover). These observations reinforce the detection and the characterization of the rapid environmental changes in the loess sequences. Otherwise, the quantification of the temperature and the water available during the Last Glacial are key elements to reconstruct palaeoclimate in loess sequence. This original study highlights the potential of stable isotope composition of earthworm calcite granule as a new proxy (i) for absolute mean soil and air temperature measurements and (ii) for palaeoprecipitation during the Last Glacial interstadials in continental environments and provide some clues in the knowledge of the influence of the abrupt climate variability during the Last Glacial on the Palaeolithic occupation in western Europe. De nombreux travaux récents ont mis en évidence l’extrême sensibilité des séquences loessiques ouest-européennes aux variations climatiques millénaires qui caractérisent le Dernier glaciaire. Des granules de calcite fossiles ont été découverts dans les séquences loessiques montrant de fortes concentrations dans des horizons spécifiques (paléosols). Ces granules sont produits par des vers de ...