Geochemical and sedimentological responses of Arctic glacial Lake Ilirney, Chukotka (Far East Russia) to palaeoenvironmental change since ~ 51.8 ka BP

Stuart Vyse,Ulrike Herzschuh,Bernhard Diekmann,Boris Biskaborn,Lyudmila Pestryakova,Simon Armitage,Andrei Andreev

doi:10.5194/egusphere-egu21-15799

Abstract

&lt;p&gt;Palaeoenvironmental reconstructions with temporal coverages extending beyond Marine Isotope Stage (MIS) three are scarce within the data sparse region of Chukotka, Far East Russia. The objective of this work was to infer palaeoenvironmental variability from a 10.76 m long, radiocarbon and OSL dated sediment core from Lake Ilirney, Chukotka (67&amp;#176;21&amp;#180;N, 168&amp;#176;19&amp;#180;E). We performed acoustic sub-bottom profiling of the lake basin and analysed high-resolution elements (XRF), organic carbon (TC, TN, TOC), grain-size, mineralogy (XRD) and partly also diatoms and pollen from the core. Our results affirm the application of XRF-based sediment-geochemical proxies as effective tracers of palaeoenvironmental variability within arctic lake systems. Our work reveals that a lake formed during MIS 3 from ca. 51.8 ka BP, following an extensive MIS 4 glaciation in the Ilirney valley. Catchment palaeoenvironmental conditions during this time likely remained cold associated with the continued presence of a catchment glacier until ca. 36.2 ka BP. Partial amelioration reflected by increased diatom, catchment vegetation and lake organic productivity and clastic sediment input from mixed sources from ca. 36.2 ka BP potentially resulted in a lake high-stand ~15 m above the present level and may represent evidence of a more productive palaeoenvironment overlapping in timing with the MIS 3 interstadial optimum. A transitional period of deteriorating palaeoenvironmental conditions occurred ca. 30- 27.9 ka BP and was superseded by periglacial-glacial conditions from ca. 27.9 ka BP, during MIS 2. Deglaciation as marked by sediment-geochemical proxies commenced ca. 20.2 ka BP. Our findings are compared with lacustrine, Yedoma and river-bluff records from across Beringia and potentially yield limited support for a marked Younger Dryas cooling in the study area.&lt;/p&gt;

Highlights

IntroductionRecent global climate change poses an existential threat for sensitivity and the prediction of future environmental changes (Biskaborn et al, 2012)
Despite significant studies of Holocene and late Glacial palaeoenvironmental variability within records from eastern and northeastern Russia (Biskaborn et al, 2013, 2012; Diekmann et al, 2016; Wetterich et al, 2014, 2011), palaeoenvironmental records that cover this interval within Chukotka, far east Russia are comparatively sparse (e.g. Lozhkin and Anderson, 2011 and references therein)
The paucity of Chukotkan palaeoenvironmental records has been exacerbated by the unreliability of age-depth models due to dating limitations of lacustrine and non-lacustrine records, during glacial episodes (Colman et al, 1996; Lozhkin et al, 2016)

Summary

Introduction

Recent global climate change poses an existential threat for sensitivity and the prediction of future environmental changes (Biskaborn et al, 2012). Despite significant studies of Holocene and late Glacial palaeoenvironmental variability within records from eastern and northeastern Russia (Biskaborn et al, 2013, 2012; Diekmann et al, 2016; Wetterich et al, 2014, 2011), palaeoenvironmental records that cover this interval within Chukotka, far east Russia are comparatively sparse (e.g. Lozhkin and Anderson, 2011 and references therein). The paucity of Chukotkan palaeoenvironmental records has been exacerbated by the unreliability of age-depth models due to dating limitations of lacustrine and non-lacustrine records, during glacial episodes (Colman et al, 1996; Lozhkin et al, 2016). Geochemical and sedimentological datasets from lake sediments in Chukotka are vastly underrepresented (Asikainen et al, 2007) Where they exist, such studies have principally focussed on the impact of regional climate variability without considering the interaction of specific local catchment processes that are increasingly being shown to impact strongly sediment-geochemical processes (Opitz et al, 2012). Recent research from Tibetan and Himalayan lacustrine systems have highlighted the significance of catchment fluvial, aeolian and glacial-periglacial processes and the effect of lake-level changes on lacustrine development (Lehmkuhl and Haselein, 2000; Opitz et al., 2012; Wünnemann et al, 2008)

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