Syngenetic dynamic of permafrost of a polar desert solifluction lobe, Ward Hunt Island, Nunavut

Abstract

Repeated freeze-thaw cycles on slopes trigger sorting and solifluction mass movements, while subsequent displacement of material modifies the geomorphology of slopes as well as permafrost dynamics. This study focuses on the geomorphology and the cryostratigraphy of a polar desert stone-banked solifluction lobe with the objective to clarify the impact of slow mass movements on ground ice aggradation. The morphology of the solifluction lobe was characterized by peripheral ridges of coarse gravel, partially surrounding a depression filled with finer sediments saturated with water and covered by organics. Cryostratigraphic analysis demonstrated that the solifluction lobe's formation led to the development of a syngenetic layer of permafrost with an ice content that varied according to the location in the lobe. The ice-rich cryofacies formed in the central depression of the lobe should act as a buffer to potential active layer deepening, slowing down its thawing, whereas the ice-poor cryofacies formed under the ridges is expected to thaw faster than the central depression under climate warming scenarios. Thawing of the ice-rich zone in the future will result in differential thaw subsidence between the ridges and the central depression of solifluction lobes, along with increased drainage through the ridges and subsequent changes in hydrology.Key words: solifluction lobe, cryostratigraphy, syngenetic permafrost, ground ice, polar desert.Résumé : Les cycles de gel et de dégel répétés sur les pentes déclenchent le classement granulométrique et les mouvements de masse de solifluxion, tandis que le déplacement subséquent de la matière modifie la géomorphologie des pentes ainsi que la dynamique du pergélisol. Dans le cadre de cette étude, on se penche sur la géomorphologie et la cryostratigraphie d'un lobe de solifluxion à talus de pierre d'un désert polaire, et ce, dans le but d'expliquer l'impact de lents mouvements de masse sur le colmatage des glaces de sol. La morphologie du lobe de solifluxion était caractérisée par des crêtes périphériques de gros gravier, entourant partiellement une dépression remplie de sédiments fins saturés d'eau et couverts de composé organique. L'analyse cryostratigraphique a démontré que la formation du lobe de solifluxion est à l'origine du développement d'une couche syngénétique de pergélisol ayant une teneur en glace qui variait selon l'emplacement dans le lobe. Le cryofaciès riche en glace ainsi formé dans la dépression centrale du lobe devrait servir For personal use only.de tampon à l'approfondissement possible de la couche active, ralentissant son dégel, tandis que l'on s'attend à ce que le cryofaciès pauvre en glace formé sous les crêtes dégèle plus rapidement que la dépression centrale selon divers scénarios de réchauffement climatique. Par la suite, le dégel de la zone riche en glace causera un différentiel d'affaissement attribuable au dégel, et ce, entre les crêtes et la dépression centrale des lobes de solifluxion, avec l'écoulement accru à travers les crêtes et les cha...

Water tracks in the High Arctic: a hydrological network dominated by rapid subsurface flow through patterned ground

“…This deposition process could explain the absence of sorting in Sp-4 as well as the increasing amounts of fines and the decreasing amount of carbonates Bulk density (g cm towards the soil surface. Similar stratigraphic evidence was found where surface runoff and seepage occurs (Woo and Steer 1986;Woo and Xia 1995) and has also been reported at another site on Ward Hunt Island (Verpaelst et al 2017).…”

Periglacial slopewash dominated by solute transfers and subsurface erosion on a High Arctic slope

“…From there, however, the subsurface flow can take two pathways. It can follow a path where the deposition of fine sediment has created suitable conditions for the formation of solifluction lobes, which diffuses the water through its ridges into a colluviums slope 20 . It can also evolve into a blockstream, which maintains rapid flow because of its large pore sizes.…”

“…17 This occurs as the water is funneled into the path of least resistance through coarse areas of slopes and patterned ground, traveling in similar fashion to vertical funnel flow. 18 It has been suggested that patterned ground in such regions may be created by a mix of periglacial sorting processes, leaching, and lessivage, 19,20 with the capacity to increase the hydraulic conductivity of the substrate by at least an order of magnitude. 21 Underground erosion in patterned ground has already been reported in the literature, as a process enhancing the surface expression of sorted stripes on frost-affected slopes.…”

Hillslope water tracks in the High Arctic: Seasonal flow dynamics with changing water sources in preferential flow paths

“…Their importance in the periglacial landscape extends beyond that of a simple hydrological pathway, as they play specific roles in heat transfer and active layer development (Gooseff et al, ; Hastings, Luchessa, Oechel, & Tenhunen, ; Levy & Schmidt, ; Paquette, Fortier, Mueller, Sarrazin, & Vincent, ; Paquette, Fortier, & Vincent, ), solute transport (Levy, Fountain, Gooseff, Welch, & Lyons, ), and nutrient and carbon cycling (Ball & Levy, ; Cheng et al, ; Mcnamara, Kane, Hobbie, & Kling, ; Oberbauer, Tenhunen, & Reynolds, ). They also play a role in the development of the landscape, acting as an immature drainage network (Mcnamara, Kane, & Hinzman, ), as moisture provider for slow mass wasting processes (Verpaelst, Fortier, Kanevskiy, Paquette, & Shur, ), or as indications of denudation by leaching of fine material (Paquette et al, ).…”