Changes in erosion patterns during the Holocene in a currently treeless subalpine catchment inferred from lake sediment geochemistry (Lake Anterne, 2063 m a.s.l., NW French Alps): The role of climate and human activities
2011
Giguet-Covex, Charline | Arnaud, Fabien | Poulenard, Jérôme | Disnar, Jean-Robert | Delhon, Claire | Francus, Pierre | David, Fernand | Enters, Dirk | Delannoy, Jean-Jacques | Environnements, Dynamiques et Territoires de Montagne (EDYTEM) ; Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG) | Institut des Sciences de la Terre d'Orléans (ISTO) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS) | Centre d'Études Préhistoire, Antiquité, Moyen-Age (CEPAM) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS)-Centre National de la Recherche Scientifique (CNRS) | Centre Eau Terre Environnement [Québec] (INRS - ETE) ; Institut National de la Recherche Scientifique [Québec] (INRS) | Geochimistry and Geodynamics Research Centre (GEOTOP) ; Université du Québec à Montréal = University of Québec in Montréal (UQAM) | 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) | Lower Saxony Institute for Historical Coastal Research ; Lower Saxony Institute for Historical Coastal Research | Programme INSU : Eclipse
International audience
显示更多 [+] 显示较少 [-]英语. A high-resolution sedimentological and geochemical study was performed on a 20 m long core from the alpine Lake Anterne (2063 m a.s.l., NW French Alps) spanning the last 10 ka. Sedimentation is mainly of minerogenic origin. The organic matter quantity (TOC%) as well as its quality (hydrogen (HI) and oxygen (OI) indices) both indicate the progressive onset and subsequent stabilization of vegetation cover in the catchment from 9950 to 5550 cal. BP. During this phase, the pedogenic process of carbonate dissolution is marked by a decrease in the calcium content in the sediment record. Between 7850 and 5550 cal. BP, very low manganese concentrations suggest anoxic conditions in the bottom-water of Lake Anterne. These are caused by a relatively high organic matter (terrestrial and lacustrine) content, a low flood frequency and longer summer stratification triggered by warmer conditions. From 5550 cal. BP, a decrease in TOC, stabilization of HI and higher sedimentation rates together reflect increased erosion rates of leptosols and developed soils, probably due to a colder and wetter climate. Then, three periods of important soil destabilization are marked by an increased frequency and thickness of flood deposits during the Bronze Age and by increases in topsoil erosion relative to leptosols (HI increases) during the late Iron Age/Roman period and the Medieval periods. These periods are also characterized by higher sedimentation rates. According to palynological data, human impact (deforestation and/or pasturing activity) probably triggered these periods of increased soil erosion.
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