Glacial Deposited Sediments: Evidence for Ice Sheets along Northern Rim of Beringia
The East Siberian and the Chukchi Shelf are of general interest concerning the distribution of regional ice sheets. Both shelves felt dry during glacial times, which is named Beringia. From geological onshore mapping it was proposed that Beringia did not host large ice sheets during glacial times. I...
| Main Authors: | , |
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| Format: | Conference Object |
| Language: | unknown |
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2021
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| Online Access: | https://epic.awi.de/id/eprint/55958/ https://epic.awi.de/id/eprint/55958/1/Poster_AGU2021_V4.pdf https://hdl.handle.net/10013/epic.735358ce-e4d8-4dd4-8ef2-febb0337a43e https://hdl.handle.net/ |
| Summary: | The East Siberian and the Chukchi Shelf are of general interest concerning the distribution of regional ice sheets. Both shelves felt dry during glacial times, which is named Beringia. From geological onshore mapping it was proposed that Beringia did not host large ice sheets during glacial times. Instead, a widespread mountain glaciation was suggested. However, geophysical data of the last two decades imaged a complex pattern of glaciogenic erosion of even the shallow shelf areas. The results indicate the presence of several streams in bathymetric troughs and point to an ice sheet on the outer shelf of Beringia with unknown size. Advancing ice sheets deliver large amounts of sediments to the continental margins and change the slope properties. However, the amount of delivered sediments varies along the ice sheet margin. In seismic data, these deposits form chaotic or opaque wedges separated by strong semi-continuous to continuous reflections. We use published and reprocessed 2D multi-channel seismic reflection data from R/V Marcus G. Langseth located between 147°E in the East Siberian Sea to the to 149°W in the Beaufort Sea to investigate in greater detail the glacial deposited sediments along the northern margins of Beringia. We found in this data glacial deposits relocating the shelf break up to 13 km along the slope between 175° E and 161° W. The maximum thickness of these sediments reaches up to 450 m. Deposits in the Northwind Basin between 165° W and 161° W are separated by strong reflections indicating 3-5 glacial advances. On the Kucherov Terrace between 175°E to 176°W, we found erosion and grounded ice deposits in water depths shallower than 1200 m. However, slopes in the western East Siberian Sea and in the Beaufort Sea lack of thick glacial deposits. This might indicate either less intense or no glaciation. The amounts of glacial deposited sediments along the margins of Beringia are significant smaller than the reported amounts along the Norwegian and Greenland margins. In conclusion, our results indicate a less intense glaciation of Beringia compared to other glaciated margins during the Quaternary. |
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