CONTRASTING PATTERNS OF THERMO-EROSION GULLIES FORMED IN SYNGENETIC ICE WEDGE POLYGONAL TERRAINS ON BYLOT ISLAND, EASTERN CANADIAN ARCTIC: CASE STUDIES FROM THREE DIFFERENT SEDIMENTARY ENVIRONMENTS

Audrey Veillette, Daniel Fortier, Etienne Godin

In the proceedings of: GeoQuébec 2015: 68th Canadian Geotechnical Conference & 7th Canadian Permafrost Conference

Session: Characterization of Permafrost State and Variability II / Caractérisation et variabilité du pergélisol II

ABSTRACT: Ice wedge polygonal terrains, typical of Arctic permafrost geosystems, are vulnerable to thermo-erosional gullying and thermokarst. Gullies located on Bylot Island (NU) have distinct shapes and dynamics on factors such as their age, alluvial activity level, water balance and nature of the sedimentary environment. In this paper we focus on the contrasts differencing gullies observed in aeolian sands, colluvium/alluvium and peaty-loess deposits. Polygons areas, ice wedges size and consequently gully shapes were distinct for each environment: the peaty-loess-zone had medium-sized polygons and generally larger ice wedges, which erosion resulted in well-developed multi-channel gullies. The aeolian sands-zone had smaller polygons and thinner ice wedges, where quasi-linear gullies were formed. The colluvium/alluvium-zone had large polygons with large primary ice wedges. The erosion was concentrated, very active, and essentially restricted to the primary ice wedges. The role of the ice wedges geometry and size in the evolution of the gullies was major, putting thermo-erosion gullies as distinct landforms from gullies found in warmer, non-permafrost zones.

RÉSUMÉ: Le pergélisol parsemé de polygones à coin de glace caractérisant le haut-Arctique est vulnérable au thermokarst et au ravinement. Les ravins (Ile Bylot, NU) ont une dynamique qui dépend de facteurs tels que leur âge, leur stabilité, leur bilan hydrologique et la nature de leur environnement de déposition. Cet article porte sur les contrastes propres aux ravins se trouvant dans des dépôts éoliens sableux, des loess organiques et des colluvions/alluvions. Les ravins dans la zone de loess organiques se sont formés dans des polygones de taille moyenne composés de coins de glace larges, résultant en de grands ravins multi-branches; les polygones et les coins de glace dans la zone de dépôts sableux éoliens étaient petits et les ravins résultants quasi-linéaires; en zone de colluvions, les polygones étaient e pergélisol par rapport à celui des zones tempérées non pergélisolées.

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Audrey Veillette; Daniel Fortier; Etienne Godin (2015) CONTRASTING PATTERNS OF THERMO-EROSION GULLIES FORMED IN SYNGENETIC ICE WEDGE POLYGONAL TERRAINS ON BYLOT ISLAND, EASTERN CANADIAN ARCTIC: CASE STUDIES FROM THREE DIFFERENT SEDIMENTARY ENVIRONMENTS in GEO2015. Ottawa, Ontario: Canadian Geotechnical Society.

@article{765,author = Audrey Veillette; Daniel Fortier; Etienne Godin,title = CONTRASTING PATTERNS OF THERMO-EROSION GULLIES FORMED IN SYNGENETIC ICE WEDGE POLYGONAL TERRAINS ON BYLOT ISLAND, EASTERN CANADIAN ARCTIC: CASE STUDIES FROM THREE DIFFERENT SEDIMENTARY ENVIRONMENTS,year = 2015}