Seismic constraints for ice sheets along the northern margin of Beringia

Abstract

Beringia today is a partly submerged Arctic region bordered by the Lena River in East Siberia and the Mackenzie River in North America. Whilst emergent at times of eustatic sea-level fall, the northern Beringian Margin was affected by the repeated growth and decay of regional ice sheets. The size and dynamism of these ice sheets are a subject of some debate that can be addressed using geophysical data, which reveal widespread evidence for glacial processes on the continental shelves. We use published and reprocessed 2D multichannel seismic reflection data from the northern margins of Beringia between 147° E to 149° W to investigate their glacially deposited sediments in detail. Deposition of up to 450 m of sediments caused the shelf break to migrate basinward by up to 13 km between 165° E and 161° W. On the Kucherov Terrace (175° E to 176° W) the data show evidence for erosion by grounded ice in water depths of 1200 m. Deposits in the Northwind Basin, between 165° W and 161° W, are separated by continuous reflections indicating at least 3–5 glacial advances. However, the continental slopes of the western East Siberian Sea and the Beaufort Sea lack the thick glacial deposits found in the intervening region. Overall, the volume of glacial deposited sediments along the margins of Beringia are significantly smaller than the reported amounts along the Norwegian and Greenland margins. Therefore, we suggest a less dynamic and fewer number of glaciations of Beringia compared to other glaciated margins during the Quaternary. • Evidence for multiple glacial advances along the northern rim of Beringia. • Erosion by ice sheets only to water depths of 1200 m. • Three main depocenters of glacial deposits along the Beringian margin.