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| Titel |
The marine-based NW Fennoscandian Ice Sheet: glacial and deglacial dynamics as reconstructed from submarine landforms |
| VerfasserIn |
T. A. Rydningen, T. O. Vorren, J. S. Laberg, V. Kolstad |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066146
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| Zusammenfassung |
| In this study, the configuration of the marine-based NW Fennoscandian ice sheet during the
last glacial maximum (LGM) and deglaciation were reconstructed using detailed swath
bathymetry and high-resolution seismic data. The investigated area covers about 10,000 km2
of the continental shelf outside Troms, northern Norway, where the large scale morphology
is characterized by cross-shelf and coast-parallel troughs, and banks. The glacial
landforms preserved on the seabed were mapped, and their spatial distribution discussed.
Mega-scale glacial lineations, flutes and crag-and-tails were mainly found in the
cross-shelf troughs. These are in some areas overprinted by larger end moraines
and grounding zone wedges (GZW). At the trough-bank borders, lateral moraines,
as well as shear zone moraines, were found, whereas a high density of smaller
end moraines occurred on the banks. Iceberg plough marks and dead-ice terrain
were observed both in the cross-shelf troughs and on the banks. From the mapped
landforms the extent and dynamics of the ice sheet during the LGM were deduced.
Fast-flowing ice streams are inferred in the cross-shelf troughs, while only end
moraines on the banks indicate more sluggish ice here. The marine-based part of
the Fennoscandian ice sheet was drained via fjord and valley systems inshore, fed
from the major ice dome in the east. We estimate the palaeo-ice stream velocities
during LGM to be between 260 and 330 m/year. Three deglaciation events have been
reconstructed: i) During the Torsken-1 event the marine-based ice in the troughs
retreated rapidly from the shelf break, halted or readvanced to form GZWs and the
Torsken moraine, ii) Several halts or readvances characterized the ice recession on the
shallower banks during the Torsken-2 event, and iii) In the Flesen event most of
the troughs and banks were deglaciated. However, prominent end moraines in the
inner parts of the troughs and banks indicate halts of the ice also during this event. |
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