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| Titel |
Glacial history of a mid-altitude mountain massif: cartography and dating in the Chablais area (France, Switzerland) |
| VerfasserIn |
A. Perret, E. Reynard, J.-J. Delannoy |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062369
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| Zusammenfassung |
| The Chablais area, considered as one of the cradles of glaciology (de Charpentier,
1841; Morlot, 1859), has been studied for a long time but several questions still
remain unresolved. This study aims to reconstruct the glacial history of the massif, in
order to explain the glacial landforms, which constitute an important part of the
local geomorphology. The study focuses on the last glacial cycle (OIS 5 – OIS
2).
The area is primarily associated with the the Valais glacier, by several local glacial flows
and, to a lesser extent, by the Giffre glacier. Its position at the interface of the important
Valais glacial flow and less powerful local flows is a specificity of the study area, which
implies several bifurcations, penetration of the main glacier into laterals valleys,
damming situations, and different responses of the various ice bodies to climatic
changes.
The study is divided in four steps. (1) The first step was to carry out a wide bibliographic
survey to identify the state of knowledge, especially in relation to areas previously poorly
studied and areas that needed to be reconsidered given developments in dating methods. (2)
Field surveys allowed us to complete observations and prepare local geomorphological maps
(of glacial landforms and associated phenomena). (3) The third step was to assemble
heterogeneous data (old and new maps, Digital Terrain Models, aerial photographies) in a
GIS to establish maps of glacial stages. (4) Finally, the absolute and relative chronology of
deglaciation (Guitter, 2003) was completed by cosmogenic nuclide dating. Results have
allowed us to address the conditions of glacial landform deposition and evolution
in a mid-altitude mountain range, and show the need to be prudent in comparing
results of different dating methods. Our results suggest that the ages obtained are
overall too young in regard to 10Be ages on the northern alpine foreland (Ivy-Ochs et
al., 2004) and are in conflict with 14C dates obtained in the area (Triganon et al.,
2005).
References
de Charpentier, J. (1841). Essai sur les glaciers et sur le terrain erratique du bassin du
Rhône. M. Ducloux, Lausanne.
Guiter, F. (2003). Contribution pollen-analytique à l’histoire de la végétation au cours des
derniers 100’000 ans dans la région d’Evian (Haute Savoie, France). Implications pour la
chronologie du dernier glacier du Rhône. Thèse, Université de Droit, d’Economie et des
Sciences d’Aix-Marseille, Aix-Marseille.
Morlot, A. (1859). Sur le terrain quaternaire du bassin du Léman. Bulletin de la société
vaudoise des sciences naturelles, 6, 101-108.
Triganon, A., G. Nicoud, F. Guiter, et B. Blavoux (2005). Contrôle de la construction de
l’ensemble détritique de la région d’Evian par trois phases glaciaires durant le Würm.
Quaternaire, 16(1), 57-63.
Ivy-Ochs, S., J. Schäffer, P. W. Kubik, H.-A. Synal, et C. Schlüchter (2004). Timing of
deglaciation on the northern Alpine foreland (Switzerland). Eclogae Geologicae Helvetiae,
97, 47-55. |
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