Flood and earthquake disturbance of 210Pb geochronology (Lake Anterne, NW Alps) |
| |
| Authors: | F Arnaud V Lignier M Revel M Desmet C Beck M Pourchet F Charlet † A Trentesaux & N Tribovillard |
| |
| Institution: | Bilan et Processus en Domaine Sédimentaire UMR CNRS, Universitéde Lille 1, F-59655 Villeneuve d'Ascq Cedex, France,;Laboratoire de Géodynamique des Chaînes Alpines, UMR CNRS 5025, Cedex, France,;Universitéde Savoie, F-73376 Le Bourget du Lac Cedex, France,;OSUG, UniversitéJ. Fourrier, F-38400 Saint Martin d'Hères Cedex, France,;Laboratoire de Glaciologie et Géophysique de l'Environnement, UMR CNRS 5511, F-38402 Saint Martin d'Hères Cedex, France |
| |
| Abstract: | Dating recent lake sediment records yielding disturbed 210Pb profiles has been a problem of wide interest in palaeoclimatic and palaeoseismic studies over the last few centuries. When applied to an alpine lake sedimentary record, a high-resolution sedimentological study reveals that the 210Pb profile is disturbed by the occurrence of single-event deposits triggered by two different mechanisms: flood events deposits and gravity reworking. Removing disturbed layers from the 210Pb profile yields a logarithmic depth–activity relationship. Using a simple 210Pb decay model (CFCS) provides an assessment of mean accumulation rate of `continuous sedimentation', as opposed to `event-linked sedimentation'. The correlation of the thickest four gravity-reworked deposits with historically known earthquakes permits both validation and refinement of the age–depth relationship. This refinement highlights variations in accumulation rate consistent with post-Little Ice Age climatic variations. |
| |
| Keywords: | |
|
|
