Earth’s Cryosphere, 2020, vol. XXIV, No. 4, pp. 5-16
10.21782/EC2541-9994-2020-4(5-16)

FEATURES OF FORMATION OF THE COMPOSITION OF RELIC GROUND VEINS IN THE BASE OF COVERING DEPOSITS IN THE FOREST-STEPPE OF THE TOBOL RIVER REGION

S.I. Larin1, V.A. Alekseeva2, S.A. Laukhin3, N.S. Larina4, V.l. Guselnikov5

1Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS, 86, Malygina str., Tyumen, 625026, Russia; silarin@yandex.ru
2Lomonosov Moscow State University, Faculty of Geography, 1, Leninskie Gory, Moscow, 119991, Russia
3Ordzhonikidze Russian State Geological Prospecting University, Faculty of Hydrogeology,
23, Miklukho-Maclay str., Moscow, 117997, Russia
4Tyumen State University, Institute of Chemistry, 6, Volodarskogo str., Tyumen, 625003, Russia
5LLC EcoStroiPererabotka, 1, Chernyshevskogo str., Tyumen, 625001, Russia

The results of studying of the morphology and material composition of relic polygonal structures – small cracks, pockets, and larger wedge-shaped veins, stripped at the base of the covering carbonated deposit strata within the second fluvial terrace of the Tobol River valley – are presented. The particle size distribution analysis of the studied deposits displays the predominance of the coarse silt and fine sand fractions. The quartz grain surface textures reveal the predominance of sand grain with aeolian processing (up to 92 %). The total fraction of particles with eluvial features and traces of water transfer is small and ranges from 0 to 12–16 and 4 to 8 %, respectively. The particle roundness ratio varies from 51 to 59 %, averaging 54 % through the vein section. High values of the quartz grain fraction with traces of cryogenic processing (60–84 %), as well as the coefficient of cryogenic contrast (1.03–1.99) reflect the intense manifestation of cryogenic processes during the vein formation. Geochemical proxies and major element indices demonstrate a low degree of hypergenic transformation of the sediments filling the veins. The obtained data have revealed that the formation of the studied structures as originally ground veins in the active layer (possibly together with drying cracks), had occurred in the second half of the Sartan cryochron and at the beginning of the Holocene.

Key words: cryogenesis, polygonal structures, covering deposits, Sartan cryochron, particle size distribution analysis, quartz grain surface texture, cryogenic contrast ratio, geochemical indices, aeolian processes

Please cite as:

Larin S.I., Alekseeva V.A., Laukhin S.A., Larina N.S., Guselnikov V.l. Features of formation of the composition of relic ground veins in the base of covering deposits in the forest-steppe of the Tobol river region.  Earth’s Cryosphere, 2020, vol. XXIV, No. 4, pp.5-16, DOI: 10.21782/EC2541-9994-2020-4(5-16)