Internal structure, dynamics and genesis of small debris-covered glacier systems located in alpine permafrost environments

• Main Author: Bosson, Jean-Baptiste
• Format: Thesis
• Language: English
• Published: Université de Lausanne, Faculté des géosciences et de l'environnement 2016
• Subjects: geo; envir; Bris; Ice; permafrost
• Online Access: https://serval.unil.ch/resource/serval:BIB_5295901FC463.P001/REF.pdf; http://nbn-resolving.org/urn/resolver.pl?urn=urn:nbn:ch:serval-BIB_5295901FC4632

Small debris-covered glaciers are commonly associated with large and possibly frozen sediment accumulations in alpine permafrost environments. Tens of thousands of these complex systems, referred to herein as small de- bris-covered glacier systems located in alpine permafrost environments (SDCGSAPE), are present on Earth and similar landforms were observed on Mars. Their absolute number even increases around the world in the current climatic context. Glaciers become smaller and less dynamic with the recent intensification of glacier decline. Ice melt rate is especially rapid in temperate environments and ice masses are progressively confined within the cold- est areas, subject to permafrost conditions. Finally, the debris layers on the glaciers surface extend in high relief environments, due to the deglaciation and permafrost degradation in the surrounding relief, and the decrease of glacier dynamics. Dynamics of small glaciers, glacier-permafrost interactions or the influence of the debris cover on glaciers behaviour remain however topics rather understudied by the scientific community. Thus, despite their very large and increasing numbers, and their importance as freshwater reservoirs and sediment accumulations in high relief environments, SDCGSAPE are still barely known. This contribution synthetizes the results of five years of researches on these complex systems. Their internal struc- tures, dynamics and genesis were investigated in seven sites, located in the northwest Alps. The results collected and the review of scattered literature allowed to lay the foundation of a comprehensive knowledge on these fascinating systems. Ice and debris concentrations varied in time and space in these systems according to Holocene climatic fluctu- ations. The current highest ice concentration was found in the upper central zone of each study site, where a small glacier, inherited from past climate, subsisted. The glacier was the most dynamical components of these systems. Glacier flow and thinning were observed, reaching ...