Abstract
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 paper is to infer palaeoenvironmental variability from a 10.76 m long, OSL- and 14C- dated sediment core from Lake Ilirney, Chukotka (67°21′N, 168°19′E). We analysed high-resolution sediment-geochemistry (XRF), sedimentology (TC, TN, TOC, grain-size), mineralogy (XRD) and preliminary micropalaeontological data (diatoms and pollen) from the core as well as acoustic sub-bottom profiling data from the lake basin. Our results affirm the application of XRF-based sediment-geochemical proxies as effective tracers of palaeoenvironmental variability within arctic lake systems. Our study reveals that a lake formed during MIS3 from 51.8 (±4.1) ka BP, following extensive MIS4 glaciation. Catchment palaeoenvironmental conditions during this time remained harsh associated with the continued presence of a catchment glacier until 36.2 (±2.6) ka BP. Partial amelioration reflected by increased diatom, catchment vegetation and lake organic productivity and clastic sediment input from mixed sources from 36.2 (±2.6) ka BP resulted in a lake high-stand ∼15 m above present and is interpreted as evidence of a more productive palaeoenvironment coincident with the MIS3 interstadial optimum. A transitional period of deteriorating palaeoenvironmental conditions occurred ∼30–27.9 ka BP and was superseded by periglacial-glacial conditions from 27.9 (±0.8) ka BP, during the last glacial maximum. Deglaciation as marked by sediment-geochemical proxies commenced at 20.2 (±0.8) 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.
Highlights
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)
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)
Summary
Recent global climate change poses an existential threat for sensitivity and the prediction of future environmental changes (Biskaborn et al, 2012). 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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