Seismic study of glacial sediments of the Chukchi Shelf, Arctic Ocean

carsten.lehmann [ at ]


Ongoing research aims to constrain the extent of grounded ice shelves around the Arctic Ocean during the last glacial periods. Here, the Chukchi region is of special interest because of its broad, shallow shelf. It is under debate if any ice sheets existed on the Chukchi Shelf, as well as their possible sources and areal extent. Bathymetric and sub bottom profiler studies of the last two decades recorded on the Chukchi Sea margins and the Arlis Plateau image complex patterns of glaciogenic erosion of the shallow sediments like Mega Scale Glacial Lineations (MSGL) at present-day water depths of more than 350 m. The different directions of those MSGL indicate the presence of several ice shelves and streams and point to an East Siberian Ice Sheet of unknown size. On the Chukchi Shelf, no evidences for the existence of a large ice shelf for water depths shallower than 350 m have been described yet. We re-processed 2D multi-channel seismic data acquired in 2011 from R/V Marcus G. Langseth to investigate glaciogenic features on the shallow shelf. Our presented data will reveal, along with sediment echosounder and bathymetric data, new insights into the glacial history of the outer Chukchi Shelf and Borderland. The first up to 300 ms TWT of the seismic data indicate eroded strata and reworked sediments separated from preglacial material by a high amplitude glacial base reflection. These layers are characterized by different seismic reflection characteristics indicating different erosion and deposition environments. Furthermore, the glacial-base reflection underlies a grounding zone wedge and recessional moraines within a bathymetric trough in modern water depths between 400 m and 600 m, indicating a stepwise glacial retreat towards the Chukchi Shelf. Moreover, one grounding zone wedge with a dimension of 48 km x 75 km as a product of several advance and retreat cycles built up on the Chukchi Rise. Our data indicate multiple glacial periods of this region as well as they document the presence of an ice shelf close to the present-day shelf edge during the Last Glacial Maximum, but provide no evidence that it extended onto the subaerial Chukchi Shelf.

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Conference (Poster)
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81. Jahrestagung der DGG.
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Lehmann, C. and Jokat, W. (2021): Seismic study of glacial sediments of the Chukchi Shelf, Arctic Ocean , 81. Jahrestagung der DGG .

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