The Cyclical Structure of the Isotopic Diagram of a Lithalsa and Its Radiocarbon Age, Sentsa River Valley, Eastern Sayan

Vasil’chuk, Y.K.; Vasil’chuk, J.Y.; Alexeev, S.V.; Budantseva, N.A.; Alexeeva, L.P.; Vasil’chuk, A.C.; Kozyreva, Y.A.; Svetlakov, A.A.

Авторы: Vasil’chuk Yu K., Vasil’chuk J.Yu, Alexeev S.V., Budantseva N.A., Alexeeva L.P., Vasil’chuk A.C., Kozyreva Ye A., Svetlakov A.A.
Журнал: Doklady Earth Sciences
Том: 489
Номер: 2
Год издания: 2019
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 1456
Последняя страница: 1460
DOI: 10.1134/S1028334X19120158
Аннотация: This paper reports on the nature and history of the mineral-rich frost heave mounds—lithalsas— developed on the first terrace of the Sentsa River in Okinsk region of Buryatia. An ice core of the lithalsa was exposed by drilling of a 20-m borehole. The most typical feature of the isotopic diagrams, which we obtained for the ice core, is their cyclical pattern illustrating isotope minima at depths of about 3–5 m, 9–12 m, and 18–21 m, separated by two distinct isotope maxima. Most likely, this demonstrates the cyclicity of the triple flooding of the growing frost heave mound and the subsequent active evaporation of lake-march waters, which are the main source of moisture for the lithalsa ice core. Based on the detailed radiocarbon dating of organic material from the upper horizons of the highest and surrounding lithalsas, we determined the time of their formation. Organic material in drained frost-susceptible soils was intensely accumulated during the period from 0.5 to 0.2 ka BP. This is the time of the beginning of the formation of permafrost, active ice-formation, and the associated frost heave and lithalsa growth. The age of at least three of four mounds studied is not older than 200 years, it coincides with the cooling at the beginning of the 19th century.
Добавил в систему: Васильчук Алла Константиновна

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