Tentative age model of marine glacial landforms and related glaciations on the East Siberian and Chukchi margins


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Frank.Niessen [ at ] awi.de

Abstract

As a relatively new discovery in the western Arctic Ocean, glacial landforms were presented and interpreted as a complex pattern of Pleistocene glaciations along the continental margin of the East Siberian and the Chukchi borderland1,2. These landforms include moraines, drumlinized features, glacigenic debris flows, till wedges, mega-scale glacial lineations (MSGL), and iceberg plough marks. Orientations of some of the landforms suggest the presence of former ice sheets on the Chukchi Borderland and the East Siberian shelf. In seismic and sub-bottom profiles there is evidence that glaciations have occurred repeatedly possibly during the Pleistocene. However, the chronology of most of these western Arctic Ocean glacial periods remained undetermined. Here we present a tentative age model for some of the younger glacial events by correlation of sediment cores with glacial landforms as seen in sub-bottom profiles and swath bathymetry. The database was obtained during RV „Polarstern“ cruise ARK-XIII/3 (2008), RV "Araon" cruises ARA03B (2012), which investigated an area between the Chukchi Borderland and the East Siberian Sea between 165°W and 170°E. The stratigraphic correlation of sediment cores is based on physical properties (wet-bulk density and magnetic susceptibility), lithology and color. The chronology of the area has been proposed by Stein et al.3 for a core from the Chukchi Abyssal Plain (PS72/340-5) and includes brown layers B1 to B9, which are dated and/or interpreted as marine isotope stages MIS 1 to MIS 7. Amongst other stratigraphic features these brown layers are used as marker horizons for lateral core correlation. Our tentative age model suggests that the youngest and shallowest (480 m below present water level; mbpwl) grounding of an ice sheet on the Chukchi Borderland is younger than B2 (interpreted as Last Glacial Maximum; LGM). There is no clear evidence for a LGM glaciation along the East Siberian margin because intensive post LGM (Younger Dryas4) iceberg scouring occurred above 350 mbpsl. On the slopes of the East Siberian Sea two northerly directed ice advances occurred, both of which are older and younger than B2 and B3, respectively. The younger advance grounded to about 700 m present water depth along the continental slope and the older to 900 m and 1100 m on the Arlis Plateau and the East Siberian continental margin, respectively. We interpret these advances as Middle Weichselian glaciations on the Beringian shelf (MIS 4 to 3). Two older glaciations can be dated as Early Weichselian (MIS 5b to 5d), of which the younger event is older and younger than B3 and B4, respectively. These glaciations can be traced by glacial wedges, MSGL in up to 1200 mbpsl and subglacial diamicton along the East Siberian margin, the Arlis Plateau, and the Mendeleev Ridge. On a seamount of the Mendeleev Ridge, at 77°36'N and 800 to 900 mbpsl, streamlined lineations suggest an ice source on the East Siberian Shelf. The related diamicton on top of the seamount is older than B3 and interpreted as relict of a MIS-5a grounded ice shelf. There are at least three glaciation visible in acoustic images from the East Siberian continental margin, which are older than MIS-5a and probably predate the Weichselian. The cores presented here did not penetrate these events and the ages remain speculative until longer cores become available.



Item Type
Conference (Poster)
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Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
PAST Gateways: 3rd International Conference and Workshop, 18 May 2015 - 22 May 2015, Potsdam, Germany.
Eprint ID
39657
Cite as
Niessen, F. , Schreck, M. , Matthiessen, J. , Stein, R. , Jensen, L. and Nam, S. I. (2015): Tentative age model of marine glacial landforms and related glaciations on the East Siberian and Chukchi margins , PAST Gateways: 3rd International Conference and Workshop, Potsdam, Germany, 18 May 2015 - 22 May 2015 .


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