An overview of the consequences of paraglacial landsliding on deglaciated mountain slopes: typology, timing and contribution to cascading fluxes

• Published in: Quaternaire
• Main Authors: Cossart, Etienne, Mercier, Denis, Decaulne, Armelle, Feuillet, Thierry
• Format: Article in Journal/Newspaper
• Language: English
• Published: Association française pour l’étude du quaternaire 2016
• Subjects: cascading system; landsliding; mountain slopes; northern hemisphere; paraglaciation; sediment fluxes; cascade sédimentaire; hémisphère nord; montagnes; mouvement de terrain; versants; geo; envir; Norway; Svalbard; Iceland
• Online Access: http://journals.openedition.org/quaternaire/6444

Three decades after the early definition of the "paraglacial" concept, a general model of paraglaciation was established, integrating the typical sediment paraglacial cascading system and the responses of associated sediment storages. The residuals of this model should now be examined and explained through controlling factors that may act at both regional (e.g. tectonics) and local (topography, lithology, etc.) scales. We compare here the patterns identified in a few mountain ranges of the northern hemisphere, located in various seismotectonic settings (especially western Alps, northwestern Scotland, central Norway, Svalbard and Iceland). By combining our field observations with a literature review, the effectiveness of the paraglacial response on mountain-slope erosion and the contribution of paraglaciation to the sedimentary cascading system are discussed. In most cases, paraglaciation generates sediment storage and aggradation in headwaters and glacial trough, as the evacuation rate into sinks remains low. Finally, paraglaciation appears to be a period of hillslope denudation, preparing reservoirs of sediments, which can only be effectively evacuated during further glaciation periods. Trois décennies après la définition initiale du concept de "paraglaciaire", un modèle général de la paraglaciation a été formalisé, intégrant la cascade sédimentaire paraglaciaire et les types de réponses des réservoirs de sédiments associés. Les écarts à ce modèle doivent maintenant être examinés et expliqués par des facteurs de contrôle agissant aussi bien à l’échelle régionale (tectonique, notamment) que locale (topographie, lithologie, etc.). Nous comparons ici des schémas établis dans quelques massifs montagneux de l'hémisphère nord, localisés dans des contextes séismo-tectoniques variés (notamment Alpes occidentales, nord-ouest de l'Ecosse, Norvège centrale, Svalbard et l'Islande). En combinant nos observations de terrain avec une recension bibliographique, nous discutons de l'efficacité de la réponse paraglaciaire sur ...