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Internal structure of a lithalsa in the Akkol Valley, Russian Altai Mountains

Auteur(s) et Affiliation(s)

IWAHANA, G.
Hokkaido Univ., Sapporo, Japon
FUKUI, K.
Caldera Sabo Museum, Tateyama, Japon
MIKHAILOV, N.
Dep. of Geography, Altai State Univ., Barnaul, Russie, Federation de
OSTANIN, O.
Dep. of Geography, Altai State Univ., Barnaul, Russie, Federation de
FUJII, Y.
National Inst. of Polar Research, Tokyo, Japon


Description :
Perennial frost mounds are present near the edges of ponds located on the terrace between the mountain flank and a valley-bottom lake in the Akkol valley. The AA. describe one mound, identified as a lithalsa, which had been eroded so as to expose almost its entire vertical cross-section, revealing its internal structure. The frozen core consisted mainly of soil segments suspended in reticulate ice lenses with a mean thickness of 11-48 mm and a maximum thickness of about 160 mm. The shapes of the soil segments matched their neighbours. Other features included soil segments suspended in the ice veins shaped like En echelon gash veins, and the presence of a radial structure of ice-rich and sediment-rich frozen bands. These features all suggest the greater importance of a differential stress field during heaving of the mound and after ice segregation, compared to the thermal gradient and water supply.


Type de document :
Article de périodique

Source :
Permafrost and periglacial processes, issn : 1045-6740, 2012, vol. 23, n°. 2, p. 107-118, nombre de pages : 12, Références bibliographiques : 43 ref.

Date :
2012

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley

Langue :
Anglais
Droits :
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