GROUND TEMPERATURE AT THE DEPTH OF ZERO ANNUAL AMPLITUDE IN THE AREA OF SUPRAPERMAFROST TALIKS IN CENTRAL YAKUTIA
L.S. Lebedeva1, N.E. Baishev1, N.A. Pavlova1, V.S. Efremov1, V.V. Ogonerov1, A.M. Tarbeeva2
1Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
2Lomonosov Moscow State University, Faculty of Geography, Makkaveev Research Laboratory of Soil Erosion and Channel Processes, Moscow, Russia
Keywords: suprapermafrost taliks, temperature at the depth of zero annual amplitude, Central Yakutia, sand deposits, groundwater, seasonally thawed layer, seasonally frozen layer, continuous permafrost
Abstract
Despite the low mean annual air temperature and low precipitation, subaerial suprapermafrost aquifer taliks are formed in some cases in the continuous permafrost zone of Central Yakutia. The paper presents an analysis of the seasonal and interannual dynamics of ground temperature in contrasting geocryological conditions - in areas of permafrost spread from the surface and in suprapermafrost subaerial taliks - of the key area of Levaya Shestakovka 20 km southwest of Yakutsk. The permafrost table in this area a occurs at depths from 0.5 to 20 m. The highest ground temperatures are typical of the area of aquiferous suprapermafrost taliks confined to gentle slopes composed of sandy sediments and covered with pine woodland. The thickness of the seasonally frozen layer reaches 3 m, and the depth of zero annual amplitudes varies from 6 to 12 m. Thawed deposits are preserved due to the continuous filtration of groundwater in them. The lowest ground temperatures are characteristic of the mire and the river floodplain. The depth of seasonal thawing varies from 0.5 to 1.0 m, and the depth of zero annual amplitudes exceeds 15 m. In recent years, slow freezing of the taliks from below has been noted due to mild cooling of the strata underlying the thawed aquifers. Beyond the area of taliks, weak multidirectional changes in ground temperature have been recorded.
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