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Impacts environnementaux sur l’érosion des sols au Pléistocène supérieur et à L’holocène dans le cratère de maar du lac du Bouchet (Massif central, France)

Environmental impact on the Late Pleistocene and Holocene soil erosion in the “Lac Du Bouchet” maar crater (Massif Central, France)
Jean-Philippe Degeai and Jean-François Pastre
p. 149-159

Abstracts

A new use of the palynological, sedimentological and chronostratigraphical data issued from the intracrateric sedimentary filling of the “Lac du Bouchet” maar (Massif Central, France) gives an opportunity to study the relationships between the environmental changes and soil erosion in this volcanic crater from the Upper Pleistocene to the Holocene. A calculation method of the volume and mass of sediment layers deposited inside the crater were developed in order to assess the mean erosion rates in the drainage basin. These rates were very high during the coldest periods of the last Würmian glaciation (Lanterne I and III, Oldest Dryas), with values ranged from 180 to 210 t.km-2.yr-1. To the opposite, the erosion was slower for the Eemian and Holocene interglacial temperate periods, with rates varying between 10 and 50 t.km-2.yr-1. From the palynological and sedimentological studies of the intracrateric deposits, these numbers can be interpreted in the context of the regional palaeoenvironmental evolution. In the cold periods, erosion was deeply intense and coarsely detrital due to the fact that the drainage area was poorly protected by a low and open steppic vegetation. In contrast, during the temperate climatic episodes, the watershed ground surface was covered with forests, which induced a quieter morphogenesis and reduction of sedimentation fluxes. Besides, we can point out a rise in erosion rates throughout the second part of the Holocene, from the Subboreal, owing to the anthropogenic regional forest clearings for land cultivation.

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References

Bibliographical reference

Jean-Philippe Degeai and Jean-François Pastre, “Impacts environnementaux sur l’érosion des sols au Pléistocène supérieur et à L’holocène dans le cratère de maar du lac du Bouchet (Massif central, France)”Quaternaire, vol. 20/2 | 2009, 149-159.

Electronic reference

Jean-Philippe Degeai and Jean-François Pastre, “Impacts environnementaux sur l’érosion des sols au Pléistocène supérieur et à L’holocène dans le cratère de maar du lac du Bouchet (Massif central, France)”Quaternaire [Online], vol. 20/2 | 2009, Online since 01 June 2012, connection on 18 April 2024. URL: http://journals.openedition.org/quaternaire/5101; DOI: https://doi.org/10.4000/quaternaire.5101

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About the authors

Jean-Philippe Degeai

Laboratoire de Géographie Physique, UMR 8591 CNRS, 92195 Meudon Cedex, France. Courriel : degeaijp@hotmail.com

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Jean-François Pastre

Laboratoire de Géographie Physique, UMR 8591 CNRS, 92195 Meudon Cedex, France. Courriel : pastre@cnrs-bellevue.fr

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Copyright

The text and other elements (illustrations, imported files) are “All rights reserved”, unless otherwise stated.

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