Search

On the basis of about 430 analyses, the 18 O and D compositions (%o) of atmospheric precipitation, ground ice, surface and inter-permafrost underground waters of cryogenic-aeolian landscapes of Central Yakutia (Eastern Siberia) are discussed. Precipitation compositions here demonstrate a large annual variation (from -6.12 to -45.0 % for δ 18 O, and from -72.1 to -350.1 % for δ D), and they are described by the Local Meteoric Water Line according to the equation δD = 7.815 18 O - 1.57). In winter and in the process of spring melting, the snow storage is subjected to a significant evaporative fractionation, that is expressed by the equation δD = 6.855 18 O - 31.9. The heaviest and deuterium-depleted compositions (δ 18 O = -19.3 %, δD = -160.9, d exc = -6.7 %) are found in the last snow patches in early June. The lightest compositions similar to the present-day winter precipitation (snow) are characteristic of the polygonal wedge ices (PWI) of the Central Yakutia. The most lightweight (from -30 to -34 % for δ 18 O, and from 240 to 275% for δ D) were established to be typical for the ancient PWI, dated by the first half of the Late Pleistocene (MIS 3-4). Heavier compositions (δ 18 O = -27.2±1.4, δD = -215.8±8.5, d exc = 1.7±3.1 %) with obvious features of evaporative fractionation correspond to younger PWI (MIS 2-1). The heaviest compositions (δ 18 O = -12.2±0.7, δD = -99.2±4.7, d exc = -2.0±0.8 %) and high angular coefficients of approximating equations were determined in the investigated cave ices of sublimation origin, that implies the atmospheric origin of them. The current processes of evaporative fractionation are the most intensively reflected in the waters of aeolian lakes ( δ 18 O = -11.8±3.5, δD = -120.2±18.4, d exc = -25.8±10.5 %), and the compositions are described by the regression equation 5D = 5.52 δ 18 O - 54.12 (R 2 = 0.97). The phenomenal objects of the cryogenic-eolian landscapes of the Central Yakutia are high-debit underground sources. Among all other components of the water flows, composition of these sources is the most stable (δ 18 O = -21.6±0.8, δD = -172.6±5.1, d exc = 0.23±3.0 %). The regression of compositions of the largest underground source Bulus is approximated by the equation 5D = 6.31 δ 18 O - 36.7 (R 2 = 0.78), that is indicative to significant evaporative fractionation and close relation with the aeolian lakes in the alimentation area.

The data of the comprehensive study of deposits of dune sand massifs—the Makhatta and Kysyl-Syr Tukulans—in the Vilyui River Basin (Central Yakutia) are given. We have revealed the structure and preliminarily reconstructed the evolution of tukulans in the Vilyui River basin and the environmental conditions of the surrounding area in the Late Pleistocene–Holocene period (the chronological period of the formation of tukulans) on the basis of lithological and palynological data and 17 radiocarbon datings. It has been revealed that the tukulans should be assigned to eolian deposits formed on sediments of complicated facial structure. We have distinguished four stages in the vegetation evolution within the last 40000-year period and three chronostratigraphical phases in the development of dune massifs.