OSL dating of glacial outburst flood deposits in NE Poland and their bleaching problem inferred from the landform-sediment associations and regional context

Summary, in English

A continental-type glacial flood termed the Suwałki megafloods took place in NE Poland during the last glaciation and significantly transformed the proglacial area. This study aims, for the first time, to establish the chronology of this flood. Twenty-two sediment samples from two meltwater spillways were dated by optically stimulated luminescence. Sixteen ages from the flood megadunes are between 83 ± 11 ka and 16.9 ± 0.9 ka, whereas six ages from the outwash tracks range from 71.5 ± 9.9 ka to 20.3 ± 2.5 ka. Three dates from the uppermost part of the megadune sedimentary successions are 16.9 ± 0.9 ka, 17.9 ± 1.9 ka, and 18.8 ± 1.3 ka, and they may mark the likely true age of the Suwałki megafloods. We found no consistent relationships between the sedimentary structures and bleaching characteristics suggesting that the two are largely independent, contrary to what is typically assumed for fluvial deposits. Similarly, the transport distance from the ice margin did not exert a consistent influence on the sediment bleaching characteristics. A new hypothesis considers the stage of flooding to have a relevant impact on sediment bleaching: sediment deposited during the flood waning is well bleached and has a high potential for constraining the flood age.

• Author: Edyta Kalińska; Piotr Weckwerth; Helena Alexanderson; Jan A. Piotrowski; Wojciech Wysota
• Department/s: Department of Geology
• Publishing year: 2025-03-01
• Language: English
• Pages: 26-46
• Publication/Series: Quaternary Research (United States)
• Volume: 124
• Links: http://dx.doi.org/10.1017/qua.2024.50
• Document type: Journal article
• Publisher: Cambridge University Press
• Topic: Geology
• Keywords: Glacial megaflood; insufficient bleaching; luminescence dating; megadune; outwash plain; Weichselian glaciation
• Status: Published
• ISBN/ISSN/Other: ISSN: 0033-5894