Isotope‐Tracing for Conceptual Model Formation During the Holocene of Eletsky Palsa, Bolshezemelskaya Tundra

Abstract

ABSTRACTStudies of permafrost agradation within peat mires leading to palsa growth and palsa dynamics during the Holocene are important for predicting the future of permafrost in a changing climate. The radiocarbon age of peat cover and stable isotope composition of the ice cores of palsas near Eletsky settlement, north‐east of the European part of Russia, were studied. Palsa growth was the most active between 8 and 5 cal ka BP. The main sources for ice core formation were precipitation‐fed surface and suprapermafrost waters. It is assumed that the isotope composition of the initial water was isotopically depleted compared with modern surface waters, which may be explained by general climate cooling during earlier stages of palsa growth (response to the 8.2 ka cooling event). The ice cores of the studied palsas were formed during the freezing of water in semi‐closed conditions, mainly by the segregation mechanism during permafrost agradation, thickness of the ice lenses and ice volume could depend on freezing rates and water supply. The upper part of the palsa ice core experienced deep thawing and could be saturated with meteoric water; repeated freezing of this part of the ice core likely occurred in closed system conditions.