Rapid thermokarst evolution during the mid-Holocene in Central Yakutia, Russia

Abstract

The reconstruction of Holocene thermokarst landform evolution is important to understand the potential impact of current global climate change on permafrost regions. A multi-proxy approach was applied to analyse the sedimentological and biogeochemical characteristics as well as pollen and lacustrine microfossils of a core profile drilled in a small pingo within a large Central Yakutian thermokarst basin (alas). Age–depth modelling with macrofossil 14C ages reveals high thermokarst deposit sedimentation rates and a complete thermokarst sequence spanning about 900 years during the mid-Holocene between ~6750 and 5870 cal. yr BP. In total, three stages of thermokarst landscape evolution have been identified. Thermokarst processes were initiated at ⩽6750 to 6500 cal. yr BP. Terrestrial conditions changed quickly to lacustrine conditions, and a thermokarst lake rapidly emerged and grew to an estimated size of 120–600 m diameter and 7.5–15 m depth during only ~150 years between ~6500 and 6350 cal. yr BP. The decline of thermokarst processes and lake decrease may have been affected by local hydrological conditions between ~6350 and 5870 cal. yr BP but ceased completely after 5870 cal. yr BP, likely due to climatic changes. Clear evidence for long-lasting and stable lacustrine conditions was not obtained. The study emphasises that short-term warming led to very active permafrost degradation and rapid but locally variable modification of alas and thermokarst evolution.

Geochemical signatures of pingo ice and its origin in Grøndalen, west Spitsbergen

“…The distribution of pingos is closely linked to permafrost history, underground hydrology and climate conditions. Two pingo types are commonly distinguished, which are (1) hydrostatic (closed) system and (2) hydraulic (open) system pingos (van Everdingen, 1998). Hydrostatic pingos form when a distinct volume of pore water in water-saturated deposits is expelled towards the freezing front and freezes.…”

“…Mackay, 1986). Pingo ice and sedimentary inventories were investigated and furthermore employed in palaeoenvironmental reconstructions in the Mackenzie Delta in Canada N. Demidov et al: Geochemical signatures of pingo ice and its origin (Hyvärinen and Ritchie, 1975), on Seward Peninsula in Alaska (Wetterich et al, 2012;Palagushkina et al, 2017), in Siberia (Ulrich et al, 2017;Chizhova and Vasil'chuk, 2018;Wetterich et al, 2018), where they are called bulgunniakhs, and in northern Mongolia (Yoshikawa et al, 2013;Ishikawa and Yamkhin, 2016).…”

Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia)

“…Pingo growth and decay rates, age, and past distribution have been used for the reconstruction of past periglacial landscape conditions . Pingo inventories were furthermore used in paleo‐environmental reconstructions in the Mackenzie Delta in Canada, on Seward Peninsula in Alaska and in Central Yakutia . A modern spatial database shows more than 6000 pingos in a 3.5 × 10 6 km 2 region in the Eurasian Subarctic and Arctic, and links the pingo distribution to permafrost and landscape characteristics, to surface geology and morphology, and to hydrology and climate …”

“…[9][10][11][12] Pingo inventories were furthermore used in paleo-environmental reconstructions in the Mackenzie Delta in Canada, 13 on Seward Peninsula in Alaska 14,15 and in Central Yakutia. 16 A modern spatial database shows more than 6000 pingos in a 3.5 × 10 6 km 2 region in the Eurasian Subarctic and Arctic, and links the pingo distribution to permafrost and landscape characteristics, to surface geology and morphology, and to hydrology and climate. 17 In the course of Russian-German fieldwork in 2012 in the Kolyma Lowland, 18 different features of periglacial landscapes were studied, including a pingo exposure near Pokhodsk (Figure 1, 69°2′18.096″N, 161°0′23.112″E).…”

Pingo development in Grøndalen, West Spitsbergen

“…Mackay, 1986). Pingo ice and sedimentary inventories were investigated and furthermore employed in palaeoenvironmental reconstructions in the Mackenzie Delta in Canada (Hyvärinen and Ritchie, 1975), on Seward Peninsula in Alaska (Wetterich et al, 2012;10 Palagushkina et al, 2017), in Siberia (Ulrich et al 2017;Chizhova and Vasil'chuk, 2018;Wetterich et al, 2018), where they are called 'bulgunniakhs', and in northern Mongolia (Yoshikawa et al, 2013;Ishikawa and Yamkhin, 2016).…”