Abstract
During the past 5 years the coastal zone offshore the northern part of the island of Sylt, has been
investigated by sparker seismics and high-resolution subbottom profiling. The North Sea sector of
the area is characterized by northward-directed sediment bypass as a result of strong long-shore
(tidal) currents heading towards the Lister Tief. The southern part of Lister Tief is characterized by
the presence of a major dune field with up to 8 m high compound dunes with wavelengths up to 350
m indicative of easterly-directed sediment transport (flood dominated). Further to the northwest, in
the outer delta, a dune field suggesting westerly-directed sediment transport is identified. The two
dune fields appear to be separated by minor indefinite bed forms. The northern part of the Lister
Tief is characterised by the presence of a channel with a depth of 20-30 mbsf (meter below sea level)
(30-40 msec TWT (Two Way Traveltime)) and displaying erosion towards the north. At the western
termination of the channel the sediment transport pathway appears to be divided into two directions;
one towards the outer delta, and one towards the sediment depocenter SW of Rømø. The Lister Ley is
characterized by the presence of minor dunes, indicative of flood-current control, apart from a central
zone where ebb-tide is responsible for northward-directed sediment transport. Sparker seismic and
Chirp III data are consistent with processes having been persistent throughout the Holocene. Based
on the study a model for the current direction and sedimentation regime is suggested.
investigated by sparker seismics and high-resolution subbottom profiling. The North Sea sector of
the area is characterized by northward-directed sediment bypass as a result of strong long-shore
(tidal) currents heading towards the Lister Tief. The southern part of Lister Tief is characterized by
the presence of a major dune field with up to 8 m high compound dunes with wavelengths up to 350
m indicative of easterly-directed sediment transport (flood dominated). Further to the northwest, in
the outer delta, a dune field suggesting westerly-directed sediment transport is identified. The two
dune fields appear to be separated by minor indefinite bed forms. The northern part of the Lister
Tief is characterised by the presence of a channel with a depth of 20-30 mbsf (meter below sea level)
(30-40 msec TWT (Two Way Traveltime)) and displaying erosion towards the north. At the western
termination of the channel the sediment transport pathway appears to be divided into two directions;
one towards the outer delta, and one towards the sediment depocenter SW of Rømø. The Lister Ley is
characterized by the presence of minor dunes, indicative of flood-current control, apart from a central
zone where ebb-tide is responsible for northward-directed sediment transport. Sparker seismic and
Chirp III data are consistent with processes having been persistent throughout the Holocene. Based
on the study a model for the current direction and sedimentation regime is suggested.
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Bulletin of the Geological Society of Denmark |
| Vol/bind | 58 |
| Sider (fra-til) | 15-27 |
| Antal sider | 13 |
| ISSN | 0011-6297 |
| Status | Udgivet - 2009 |