Basin evolution and palaeoenvironmental variability of the thermokarst lake El'gene‐ Kyuele, Arctic Siberia

• Published in: Boreas
• Main Authors: Schleusner, Philipp, Biskaborn, Boris K., Kienast, Frank, Wolter, Juliane, Subetto, Dmitry, Diekmann, Bernhard
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Arctic; Thermokarst; Tundra; Siberia
• Online Access: http://dx.doi.org/10.1111/bor.12084; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12084; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12084

Thermokarst lakes are a widespread feature of the A rctic tundra, in which highly dynamic processes are closely connected with current and past climate changes. We investigated late Q uaternary sediment dynamics, basin and shoreline evolution, and environmental interrelations of L ake E l'gene‐ K yuele in the NE S iberian A rctic (latitude 71°17′ N , longitude 125°34′ E ). The water‐body displays thaw‐lake characteristics cutting into both P leistocene I ce C omplex and H olocene alas sediments. Our methods are based on grain size distribution, mineralogical composition, TOC / N ratio, stable carbon isotopes and the analysis of plant macrofossils from a 3.5‐m sediment profile at the modern eastern lake shore. Our results show two main sources for sediments in the lake basin: terrigenous diamicton supplied from thermokarst slopes and the lake shore, and lacustrine detritus that has mainly settled in the deep lake basin. The lake and its adjacent thermokarst basin rapidly expanded during the early H olocene. This climatically warmer than today period was characterized by forest or forest tundra vegetation composed of larches, birch trees and shrubs. Woodlands of both the HTM and the L ate P leistocene were affected by fire, which potentially triggered the initiation of thermokarst processes resulting later in lake formation and expansion. The maximum lake depth at the study site and the lowest limnic bioproductivity occurred during the longest time interval of ∼7 ka starting in the H olocene T hermal M aximum and lasting throughout the progressively cooler N eoglacial, whereas partial drainage and an extensive shift of the lake shoreline occurred ∼0.9 cal. ka BP . Correspondingly, this study discusses different climatic and environmental drivers for the dynamics of a thermokarst basin.