An integrated palaeoenvironmental investigation of a 6200 year old peat sequence from Ile de la Possession, Iles Crozet, sub-Antarctica

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Van Der Putten, N., Hébrard, J.P., Verbruggen, C., Van De Vijver, B., Disnar, Jean-Robert, Spassov, S., De Beaulieu, Jacques-Louis, De Dapper, M., Kéravis, Didier, Hus, Jozef, Thouveny, Nicolas, Frenot, Yves
• Other Authors: Geography Department, Universiteit Gent = Ghent University Belgium (UGENT), Institut Méditerranéen d'Ecologie et de Paléoécologie (IMEP), Université Paul Cézanne - Aix-Marseille 3-Centre National de la Recherche Scientifique (CNRS)-Avignon Université (AU)-Université de Provence - Aix-Marseille 1, National Botanic Garden of Belgium, Department of Cryptogamy, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Section du Magnétisme Environnemental, Centre de Physique du Globe de l?Institut Royal Météorologique de Belgique, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Ecosystèmes, biodiversité, évolution Rennes (ECOBIO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), French Polar Institute (Programme IPEV 136) and the CNRS (Zone atelier de recherches sur l'environnement antarctique et subantarctique)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Palaeoecology; Palaeoclimate; Macrofossil record; Rock magnetism; Geochemical analysis; Diatoms; Iles Crozet; Sub-Antarctic; Holocene; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Antarc*; Antarctica
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00342423; https://hal-insu.archives-ouvertes.fr/insu-00342423/document; https://hal-insu.archives-ouvertes.fr/insu-00342423/file/VanDerPutten-PPP-2008.pdf; https://doi.org/10.1016/j.palaeo.2008.09.014

International audience A 6200 year old peat sequence, cored in a volcanic crater on the sub-Antarctic Ile de la Possession (Iles Crozet), has been investigated, based on a multi-proxy approach. The methods applied are macrobotanical (mosses, seeds and fruits) and diatom analyses, complemented by geochemical (Rock-Eval6) and rock magnetic measurements. The chronology of the core is based on 5 radiocarbon dates. When combining all the proxy data the following changes could be inferred. From the onset of the peat formation (6200 cal yr BP) until ca. 5550 cal yr BP, biological production was high and climatic conditions must have been relatively warm. At ca. 5550 cal yr BP a shift to low biological production occurred, lasting until ca. 4600 cal yr BP. During this period the organic matter is well preserved, pointing to a cold and/or wet environment. At ca. 4600 cal yr BP, biological production increased again. From ca. 4600 cal yr BP until ca. 4100 cal yr BP a “hollow and hummock” micro topography developed at the peat surface, resulting in the presence of a mixture of wetter and drier species in the macrobotanical record. After ca. 4100 cal yr BP, the wet species disappear and a generally drier, acidic bog came into existence. A major shift in all the proxy data is observed at ca. 2800 cal yr BP, pointing to wetter and especially windier climatic conditions on the island probably caused by an intensification and/or latitudinal shift of the southern westerly belt. Caused by a stronger wind regime, erosion of the peat surface occurred at that time and a lake was formed in the peat deposits of the crater, which is still present today.