The Lastglacial and Holocene seismostratigraphy and sediment distribution of Lake Bolshoye Shchuchye, Polar Ural Mountains, Arctic Russia

Abstract

Seismostratigraphical studies of the 11.8-km 2 -large and~140-m-deep Lake Bolshoye Shchuchye, Polar Ural Mountains, reveal up to 160-m-thick acoustically laminated sediments in the lake basin. Using a dense grid of seismic lines, the spatial and temporal distributions of the sedimentary history have been reconstructed. Three regional seismic horizons have been identified and correlated with the well-dated 24-m-long sediment core retrieved from the lake. Isopach maps constructed from the seismic data show four phases of sedimentation. A contour map of the deepest regional seismic reflector represents the earliest hemipelagic sedimentation in the lake. Three contour maps represent time intervals covering the last 23 cal. ka based on the well-dated core stratigraphy from the lake. The detailed time constraints on the upper stratigraphical units in the lake allow calculation of the lakes development in terms of sediment fluxes and the denudation rates from the Last Glacial Maximum (LGM) to the present. The sedimentation in Lake Bolshoye Shchuchye has been dominated by hemipelagic processes during at least the last 24 cal. ka BP only locally interrupted by delta progradation and slope processes. A major shift in the sediment accumulation at c. 18.7 cal. ka BP is interpreted to mark the end of the local glacial maximum, greatly reduced denudation and the onset of the deglaciation period; this also demonstrates how fast the glaciers melted and possibly disappeared at the end of the LGM. The denudation rate during the Holocene is only a fifth of the LGM rate. The age of the oldest stratified sediments in Lake Bolshoye Shchuchye is not well constrained, but estimated as c. 50-60 ka.

Glacial and environmental changes over the last 60 000 years in the Polar Ural Mountains, Arctic Russia, inferred from a high‐resolution lake record and other observations from adjacent areas

“…Alluvial fans along the present shore of the lake Along the eastern shore of the lake, there are several prominent alluvial fans that have been deposited in front of ravines that are carved deeply into the steep bedrock valley sides (Figs 3, 4B). The seismic profiles suggest that these inclined deposits have been the source for many debrisflows in the lake (Haflidason et al 2019a). The fan surfaces consist for the most part of coarse gravel and boulders.…”

“…We mapped the sediment distribution with seismic methods, including a Sparker and sub-bottom profiler during the summerof 2007; methods and results are described by Haflidason et al 2019a). In 2007, we also collected three short cores that were up to 3.2 m long (506-45, -46, -47) by using a light piston-coring device (Table 1, Fig.…”

“…Seismic profiles revealed that the largest and deepest of them, Bol. Shchuchye, contains up to 160-mthick, acoustically laminated sediments above basement (Haflidason et al 2019a). This discovery opened up entirely new research questions and perspectives that we are now pursuing in collaboration with the German-Russian project Paleolimnological Transect (PLOT).…”

“…Cores retrieved from the shallow Lake Gerdizty on the eastern foothills of the mountains reached back to the transition between MIS 4 and MIS 3 at about 65 ka (Svendsen et al 2014). Shchuchye, contains up to 160-mthick, acoustically laminated sediments above basement (Haflidason et al 2019a). In search of more suitable high-resolution archives, we then moved to the much deeper lake basins of Bol.…”

Seismic stratigraphical record of Lake Levinson‐Lessing, Taymyr Peninsula: evidence for ice‐sheet dynamics and lake‐level fluctuations since the Early Weichselian

“…Melles et al 2012;Johnson et al 2016), (ii) reconstruct past lake-level fluctuations (e.g. Charlet et al 2008;Waldmann et al 2010;Greenwood et al 2015;Haflidason et al 2019). Lindhorst et al 2015;Cukur et al 2017).…”