Calibration of microcharcoal proxy preserved in the marine sediment and reconstruction of paleofires in the Western Mediterranean region during the Holocene

• Main Author: Genet, Marion
• Other Authors: Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux, Anne-Laure Daniau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2022
• Subjects: Fire regime; Microcharcoal; Mediterranean region; Holocene; Régime de feu; Microcharbons; Région méditerranéenne; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; North Atlantic; North Atlantic oscillation
• Online Access: https://theses.hal.science/tel-03662242; https://theses.hal.science/tel-03662242/document; https://theses.hal.science/tel-03662242/file/GENET_MARION_2022_CORR.pdf

Microcharcoal particles were analyzed in marine surface sediments collected in the eastern Atlantic Ocean off the Iberian Peninsula and in the western Mediterranean Sea. They were also analyzed in a marine sedimentary record from the Gulf of Lion covering the last 8500 years. The concentration and morphometric parameters of the microcharcoal in the surface sediments were compared to factors that may influence the production, transport and deposition of microcharcoal in the ocean. At the scale of the Iberian Peninsula, high concentrations of highly elongated microcharcoal in surface sediments indicate rare, large and high intensity fires. Low concentrations of weakly elongated microcharcoal indicate frequent, smaller, lower intensity fires. At the Western Mediterranean scale, high concentrations of weakly elongated microcharcoal indicate high intensity fires under cool climatic conditions or low intensity fires propagating in closed and shrubby vegetation under warm and dry climatic conditions. Higher concentrations of highly elongated microcharcoal indicate fires in open, mixed vegetation under hot and dry conditions. The results observed at the Iberian Peninsula scale were applied to a marine sedimentary record covering the Holocene in the southwestern Iberian Peninsula. Thus, rare and large fires of high intensity are described since 8000 years coinciding with the progressive opening of the vegetation. The results observed at the Mediterranean scale were applied to a marine sedimentary record off southeastern France. Thus, between 8500 and 2700 years ago, rare small fires of high intensity are described whereas since 2700 years ago, an alternation of rare small fires of high intensity and frequent and large fires of low intensity is described. The occurrence of fires in southeastern France could be related to cold events, to the decrease of solar activity and to the negative modes of the North Atlantic Oscillation and of the East Atlantic atmospheric condition. Les microcharbons ont été analysés dans des ...