Earth’s Cryosphere, 2023, Vol. XXVII, No. 1, p. 3-11.

REGIONAL AND HISTORICAL GEOCRYOLOGY

LATE HOLOCENE CRYOGENIC DEFORMATIONS IN FLOODPLAIN SEDIMENTS OF RIVER VALLEYS IN THE SELENGA RIVER BASIN

Yu.V. Ryzhov1–3,*, V.L. Kolomiets4, M.V. Smirnov1,3

1 Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, Lermontova St. 128, Irkutsk, 664033 Russia
2 Sochava Institute of Geography, Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya St. 1, Irkutsk, 664033 Russia
3 Irkutsk State University, Lenina St. 1, Irkutsk, 664003 Russia
4 Geological Institute, Siberian Branch of the Russian Academy of Sciences, Sakhyanovoi St. 6a, Ulan-Ude, 670047 Russia
*Corresponding author; e-mail: ryv@crust.irk.ru

The morphology and age of cryogenic deformations (cryoturbations and ground wedges) in the Holocene floodplain sediments of river valleys in the Selenga River basin within the areas of seasonal, discontinuous, sporadic, and isolated permafrost were studied. Late Holocene ground wedges and cryoturbations were identified in the seasonally frozen layer of floodplain sections of the Itantsa, Il’ka, and Orkhon rivers. The time of formation of the cryogenic deformations was determined on the basis of detailed morphological descriptions and dating of low and high floodplain sediments of these rivers. The age of the alluvium with cryoturbation on the low floodplain is less than 2 kyr. Cryogenic deformations on the high floodplain formed in the Late Holocene (the last 4.2 kyr). It was determined that alluvium layers with cryoturbation are underlain by moderately wet to satiated wet loamy sands and loams. Cryogenic deformations are considered a paleoclimatic indicator of the Late Holocene in the Transbaikal region and northern and central Mongolia.

Keywords: frost cracking, ground wedge, cryoturbation, floodplain, Late Holocene, Selenga River Basin

Recommended citation: Ryzhov Yu.V., Kolomiets V.L., Smirnov M.V., 2023. Late Holocene cryogenic deformations in floodplain sediments of river valleys in the Selenga River basin. Earth’s Cryosphere XXVII (1), 3–11.