Search results for "Glaciaire"
showing 9 items of 9 documents
Evidence of a complex phylogeographic structure in the common dormouse, Muscardinus avellanarius (Rodentia: Gliridae)
2012
Contact: amouton@ulg.ac.be; International audience; This is the first mitochondrial phylogeography of the common dormouse, Muscardinus avellanarius (Linnaeus, 1758), a hibernating rodent strictly protected in Europe (Habitat Directive, annex IV; Bern Convention, annex III). The 84 individuals of M. avellanarius, sampled throughout the distributional range of the species, have been sequenced at the mitochondrial DNA gene (cytochrome b, 704 base pairs). The results revealed two highly divergent lineages, with an ancient separation around 7.7 Mya and a genetic divergence of 7.7%. Lineage 1 occurs in Western Europe (France, Belgium, and Switzerland) and Italy, and lineage 2 occurs in CentralNor…
Subglacial depositional models and tunnel valley infill : example in the Quaternary record (Bray, Ireland) and application to the Upper Ordovicien re…
2012
The icehouse period during the lower Palaeozoic led to the development of large continental ice-sheet over the Gondwana. This ice-sheet fluctuated in size and repeatedly recovered the north-Gondwana platform. The resulting glacial record includes major erosional surfaces of regional extent, with subglacial landforms and morphologies, as well as glacial valleys and specific glaciogenic sedimentary record. Among these valleys, tunnel valleys refer to Quaternary analogues, associated with the development of ice-sheets over Europe and North-America. Tunnel valley defines elongated, linear to slightly sinuous depressions, measuring few kilometers in width and several kilometres in length. They s…
Quantification de l’ablation d’un bassin versant marno-calcaire alpin durant le Petit Age Glaciaire par l’étude d’un système lacustre (cas du lac du «…
2002
Measurements of present-day erosion may give heterogeneous results according to the methods used. This article proposes an approach to erosion during the Little Ice Age by the quantitative analysis of detritical materials trapped in a dammed lake. This infill is recognized through two drillings, and these specific observations are supplemented by a seismic reflexion survey which provided a reliable estimate of the geometry of the lake infill. The sedimentary production is calculated from three pieces of data: (1) the surface of the drainage area, (2) duration of the lake system activity and (3) the volume of trapped sediments. From the three determined variables, we propose a detritical product…
Structures de déformation induites par surpressions de fluide dans les environnements sous-glaciaires et marin profonds : implications paléoenvironne…
2014
Soft-sediment deformation structures (SSDs) occur in unconsolidated sediments, during or shortly after deposition. SSDs are abundant in subglacial and deep-marine environments because of the development of fluid overpressure. Case studies of these two sedimentary environments were used (1) to reconstruct palaeoenvironments from SSDS, and (2) to define the impacts of SSDS on glacial morphologies and (3) petrophysical properties.(1) Analyses of strain regimes, deformation mechanisms, and chronologies in SSDs served to improve palaeoenvironmental reconstructions. These structures were used as proxys to estimate variations of ice flow velocities, ice thickness, meltwater production, and positio…
Un enregistrement des flux sédimentaires sous glaciaires dans le lac du front de la mer de glace (Chamonix-France) : Bilans perspectives
2003
Le Quaternaire franc-comtois. Essai chronologique et paléoclimatique.
1982
Le but de ce travail est d'établir le cadre chronologique et paléoclimatique du Quaternaire en Franche-Comté à partir de l'étude des formations édifiées au cours de cette période.Deux grands types de dépôts ont été plus particulièrement étudiés: ·- Les remplissages karstiques d'avens, de porches de grottes et d'abris sous roche, donnant un éclairage intense, mais ponctuel, de l'environnement physique et biologique, grâce aux faunes abondantes et aux indices climatiques d'ordre sédimentologique.- Les dépôts glaciaires et paraglaciaires (moraines, fluvioglaciaires, glacio-lacustres) qui permettent de situer des coupures climatiques au cours du temps dans l'espace géographique étudié.L'étude d…
Intérêt de l’utilisation de la photogrammétrie SfM (Structure from Motion) pour le suivi des processus nivo-glaciaires. Application au bassin du glac…
2015
National audience; L’Arctique est reconnu comme un ex¬cellent indicateur des évolutions clima¬tiques contemporaines : sa sensibilité aux moindres sollicitations climatiques en fait une zone d’étude idéale. L’étude des pro¬cessus et des dynamiques glaciaires revêt, dans ce contexte, un intérêt majeur afin de mieux comprendre les impacts du climat sur la récession glaciaire observée durant cette dernière décade.
Analyse morphologique de talwegs et comportement scalant : applications des dimensions non-entières à la géographie physique
1999
Morphological talweg analysis and scaling behaviour: applying non-integer dimension to physical geography. -- The organisation of the talweg network is fundamental to the erosion system on the silty loamy plateaux of north-western France. The morphology of the Pays de Caux is a good example of successive runoff concentration caused by the nesting of small dry valleys. These are inherited from a periglacial climate and their general direction is governed by tectonics. However the detailed pattern of these forms remains complex and without obvious explanation. Non-integer dimensions may offer a ceratin logic to this relatively chaotic pattern. This paper has therefore sought to demonstrate th…
Caractérisation des marqueurs sédimentaires du ruissellement sur un massif saharien au Tardiglaciaire et à l'Holocène inférieur (Termit, Niger orient…
2007
13 pages; International audience