Termokarst i neotektonika (na primere Jano-Omolojskogo mezdurec'ja) Thermokarst et néotectonique, l'interfluve Jana-Omoloj servant de référence
Géographie de l'Europe ; Jakutija ; Néotectonique ; Périglaciaire ; Thermokarst ; URSS d'Asie
La tectonique agit en fracturant les roches gelées et en modifiant les conditions de l'échange de chaleur| ainsi elle influence la disposition des lacs de thermokarst.
Inherited features ; New Jersey ; Palaeogeography ; Periglacial features ; Permafrost ; Pleistocene ; Quaternary ; Sedimentary structure ; Thermokarst ; United States of America
permafrost degraded. These structures are interpreted in the context of the current understanding of thermokarst processes operating in permafrost regions today.
Asian part of Russia ; Climatic variation ; Climatic warming ; Fire ; Periglacial features ; Permafrost ; Sakha ; Salinisation ; Thawing ; Thermokarst
In spite of current climatic warming, there is no noticeable increase in regional thermokarst in Central Yakutia. Periodic forest fires significantly increase soil thermal conductivity and progressive soil salinization is occurring; however
, these are insufficient to cause thaw of the underlying icy sediments. Instead, active thermokarst should be regarded as a short-term catastrophic process. Use of the Kudryavtsev algorithm indicates that the depth of thaw beneath a water body in Central Yakutia can reach
8-10 m within 50 years, and 20+ m within 300 years. Field observations show that current thermokarst has a tendency for fast (5-10+ cm/year) subsidence.
Arctic Region ; Canada ; Cold area ; Delta ; Hydrochemistry ; Lake ; Northwest Territories ; Permafrost ; Thermokarst ; Tundra ; Water quality
Chemical data are presented for water from 22 lakes in small upland catchments (
) concentration of the pristine lakes is greater than the mean concentration of lakes disturbed by thermokarst slumping. Soluble materials released from degrading permafrost are transported to lakes by surface runoff, elevating concentrations in lake water
. The percentage of total basin area influenced by thermokarst is positively associated with ionic concentrations in lake water and inversely related to DOC.
Alaska ; Arctic Region ; Bathymetry ; Bedrock ; Coastal plain ; Geomorphometry ; Lake ; Permafrost ; Thermokarst
Detailed bathymetric data were collected for 28 thermokarst lakes across the Arctic Coastal Plain (ACP) of northern Alaska from areas with distinctly different surficial sediments and topography. Based on the variety of lakes that were surveyed
in the 3 study areas, these data suggest that thermokarst lake morphometry largely depends on the characteristics of the substrate beneath the lake and the availability of sediments eroded at the lake margin.
Asian part of Russia ; Coastal environment ; Cold area ; Geographical information system ; Periglacial features ; Remote sensing ; Satellite imagery ; Siberia ; Thermokarst
CORONA images have been used for the mapping of periglacial features on the Bykovsky Peninsula and adjacent Khorogor Valley. Features, mapped and analysed within a geographical information system, include thermokarst depressions, thermo-erosional
valleys, thermo-erosional cirques, thermokarst lakes, thermokarst lagoons and pingos. More than 50% of the area is strongly influenced by thermally-induced subsidence. Thermokarst in the area is probably less active today than in the early-middle Holocene.
Frozen ground ; Pedogenesis ; Periglacial features ; Russia ; Sedimentation ; Soil ; Thermokarst ; Yakutia
Alases are very dynamic, often geochemically closed thermokarst basin topographic forms that have a thin active layer and unique conditions of pedogenesis and vegetation development. In central Yakutia alone, there are about 16,00 alases
, with a total area of more than 4,400 km2. A unique process occurs in thermokarst depressions of central Yakutia, and it facilitates the formation of the alases themselves, as well as unique polycyclic parent materials. Due to periodic desiccation of lakes
The AA. review the literature that has contributed to our understanding of patterns, processes and feedbacks, and the environmental consequences of thermokarst, focusing on hillslope, thaw lake and wetland processes. Advances in remote sensing
techniques, and their application in a broad suite of change detection studies, indicate recent increases in the rates and magnitude of thermokarst. Field-based studies and modelling have enhanced the knowledge of processes and feedbacks associated
with warming permafrost, changes in talik geometry and accelerated thaw slump activity, and thaw lake expansion. Thermokarst research provides an important context for studying the environmental implications of permafrost degradation. Investigation
of the interactions between thermokarst and hydrologic and ecological processes has improved knowledge of the feedbacks that accelerate change or lead to stabilisation in terrestrial and thaw lake environments. Finally, the influence of permafrost thaw on soil carbon
dynamics will be an important focus of thermokarst research because of feedbacks with the global climate system.
Climatic and ecological controls on ice segregation and thermokarst: the case history of a permafrost plateau in northern Quebec
Baie ; Canada ; Dendrochronologie ; Glace du sol ; Hudson ; Mollisol ; Neige ; Palse ; Pergélisol ; Plateau ; Périglaciaire ; Québec ; Stratigraphie ; Température du sol ; Thermokarst ; Végétation
Active layer ; Bay ; Canada ; Dendrochronology ; Ground ice ; Hudson ; Palsa ; Periglacial features ; Permafrost ; Plateau ; Quebec ; Snow ; Soil temperature ; Stratigraphy ; Thermokarst ; Vegetation
couvert nival et l'analyse dendrochronologique de 209 épinettes. Mise en évidence de 4 couches, analyse de leur contenu en glace et du fonctionnement du thermokarst.
Asian part of Russia ; Geomorphology ; Glacial features ; Periglacial features ; Permafrost ; Thermokarst ; West Siberia
Les AA. proposent une série d'exemples pris en différents secteurs de cette région de Sibérie occidentale, où la relation du thermokarst lacustre et de versant actuel et récent avec des reliques de la glaciation est prouvée par la nature des glaces
elles-mêmes, dont les affleurements sont rares et éphémères, ainsi que par les conditions géomorphologiques et géologiques. Les AA. montrent également le rapport entre le thermokarst glaciaire et les principaux éléments de la morphosculpture glaciaire.
Nature and importance of thermokarst processes, Sand Hills moraine, Banks Island, Canada
Arctique canadien ; Banks Island ; Canada ; Couche active ; Dune ; Dynamique de versant ; Erosion littorale ; Glissement de terrain ; Géographie physique ; Littoral ; Moraine ; Mouvement de masse ; Permafrost ; Périglaciaire ; Thermokarst
Des mouvements de masse importants se produisent dans la moraine de Sand Hills. Ils sont dus au retrait du thermokarst et à l'érosion littorale. Les vitesses d'érosion sont particulièrement rapides (8,6 à 11,4 m/a). Les taux d'ablation dus au
retrait du thermokarst sur 1 km de côte sont deux fois plus élevés que ceux dus au ruissellement et à la solifluxion.
Ikirouta ja termokarsti Keski-Jakutiassa. (Permafrost and thermokarst in Central Yakutia)
Géographie de l'Europe ; Géomorphologie périglaciaire ; Holocène ; Jakutskaja ASSR ; Permafrost ; Périglaciaire ; Thermokarst ; URSS d'Asie ; Yakoutie ; Zone froide
been favoured by subsequent climatic conditions. The most pronounced Holocene changes in the relief have occurred in the lowlying areas, where thermokarst features account for almost a half of the relief. The exceptionally favourable conditions
for such processes are due principally to the geological history of the region and the intensive formation of ice-wedges due to the severity of the climate. The thermokarst features, mainly in the form of alas depressions, are largely the result of climatic changes
Alaska ; Climatic change ; Cold area ; Ecology ; Periglacial features ; Permafrost ; Snow ; Snow cover ; Temperature ; Thermokarst ; Vegetation
Observations and measurements were made of physical and ecological changes that have occurred since 1985 at a tundra site near Healy, Alaska. Air temperatures decreased (1985 through 1999) while permafrost warmed and thawed creating thermokarst
temperatures and ground-ice distribution on active-layer dynamics and thermokarst, and the impacts of thermokarst terrain on water redistribution, peat accumulation and shifting vegetation composition. The results provide insights into the processes, dynamics
Biogeochemical and geocryological characteristics of wedge and thermokarst-cave ice in the CRREL permafrost tunnel, Alaska
Alaska ; Biogéochimie ; Carbone ; Charge en solution ; Coin de glace ; Eau de fonte ; Glace ; Modèle ; Nutriment ; Pergélisol ; Périglaciaire ; Thermokarst ; Zone froide
Alaska ; Biogeochemistry ; Carbon ; Cold area ; Ice ; Ice wedge ; Meltwater ; Model ; Nutrient ; Periglacial features ; Permafrost ; Solution load ; Thermokarst
Partially eroded ice wedges and lenticularly shaped bodies of massive thermokarst-cave ice in ice-rich syngenetic permafrost (yedoma) are exposed in the CRREL tunnel near Fairbanks, Alaska. Here, the AA. report the biogeochemical characteristics
of one of these thermokarst-cave ice features and four nearby ice wedges. Based on these results they present a schematic model to describe how the thermokarst-cave ice was formed and preserved and what processes led to its current biogeochemical
and permanent snow bank ice are discussed, and specific examples are given from 3 different environments (ice-cored moraines, ice-cored deltas and icings). The impacts of thermokarst and retrogressive thaw flow erosion on the preservation of ground ice are also
Action anthropique ; Arctique ; Bilan hydrologique ; Canada ; Changement global ; Effet de serre ; Inondation ; Permafrost ; Périglaciaire ; Thermokarst ; Variation climatique ; Zone froide
Arctic Ocean;Arctic Region ; Canada ; Climatic variation ; Cold area ; Flood ; Global change ; Greenhouse effect ; Human impact ; Periglacial features ; Permafrost ; Thermokarst ; Water balance
Human-induced climatic warming will have major impacts on permafrost, which presently underlies half of Canada's land mass. The extent of permafrost will diminish, accompanied by modifications of the land surface through thermokarst or mass wasting