Lithalsas in the Sentsa River Valley, Eastern Sayan Mountains, Southern Russia

Abstract

Perennial frost mounds identified as lithalsas occur in the Sentsa River valley of the Eastern Sayan Mountains, Russia. We report the first detailed study of permafrost in this region, based on analysis of the cryostructure and distribution of stable isotopes of oxygen and hydrogen, and ion concentrations from the ice‐rich cores of two lithalsas 3–7 m high. Their main cryostructures are reticulate and lenticular, with visible ice contents exceeding 50–60%. The vertical and lateral distribution of δ18О and δD values show a step‐by‐step mechanism of lithalsa growth: in the first stage a large lithalsa formed, and in the second stage a small lithalsa formed. The more negative isotope values of ice in the large lithalsa ice probably resulted from gradual release of isotopically depleted water from the central to peripheral part of the massif during ice segregation in water‐saturated fine‐grained lake sediments. Minor variations of isotope values suggest intensive recharge of lake‐fen and meteoric water supply during freezing and lithalsa growth. Copyright © 2015 John Wiley & Sons, Ltd.

Composition and origin of a lithalsa related to lake‐level recession and Holocene terrestrial emergence, Northwest Territories, Canada

“…The variation in δ 18 O values with depth in all boreholes is < 4 ‰ (Figure 5(a)) and, although values from the underlying clays are lower than those from upper sediments, the difference is not statistically significant. This finding is consistent with that of Iwahana et al (2012) andVasil'chuk et al (2015), who found small isotopic variations in lithalsas, which they attributed to an open system at the freezing front. Thus, although isotopic fractionation may occur across ice lenses (Calmels et al, 2008b), fractionation is not evident down-profile as it would be under closed-system conditions (Mackay, 1990;Lacelle, 2011).…”

“…() and Vasil’chuk et al . (), who found small isotopic variations in lithalsas, which they attributed to an open system at the freezing front. Thus, although isotopic fractionation may occur across ice lenses (Calmels et al ., ), fractionation is not evident down‐profile as it would be under closed‐system conditions (Mackay, ; Lacelle, ).…”

“…Few detailed stratigraphic investigations have been conducted to understand the geomorphic origins or field characteristics of lithalsas (Allard et al ., ; Wünnemann et al ., ; Iwahana et al ., ; Wolfe et al ., ; Vasil’chuk et al ., ). In the GSL, Wolfe et al .…”

“…Few detailed stratigraphic investigations have been conducted to understand the geomorphic origins or field characteristics of lithalsas Wünnemann et al, 2008;Iwahana et al, 2012;Wolfe et al, 2014;Vasil'chuk et al, 2015). In the GSL, Wolfe et al (2014) reported on the sediments, ground ice, electrical resistivity, and radiocarbon ages of a lithalsa, formed within the last 700 years.…”

Recent Advances (2008–2015) in the Study of Ground Ice and Cryostratigraphy

“…In the discontinuous permafrost zone, epigenetic permafrost often starts to form with the development of palsas or lithalsas, which may eventually transform into permafrost plateaus elevated above the initial ground surface by the accumulation of segregated ice. Palsas and lithalsas have been recently studied in Fennoscandia (Seppälä, ), the Altai and Sayan regions of Russia (Iwahana et al ., ; Y. K. Vasil'chuk et al ., ), the Northwest Territories (e.g. Wolfe et al ., ) and northern Quebec, Canada (Kuhry, ; Calmels and Allard, ; Calmels et al ., ), the Himalayas (Wünnemann et al ., ) and Mongolia (Sharkuu et al ., ).…”