KONTINENTALMARGIN

2D/3D crustal models of the southwestern Vøring Basin have been established from gravity,
magnetic and recent seismic data. The Rån ridge area, in particular, has been investigated and discussed.
Two regional 2D seismic lines (MNR07-7319 and MNR8-7292) provided by Repsol have been modelled
across the soutwestern Vøring Basin. They helped to better constrain some of the controversial crustal
units as well as the top basement and Moho depths. The modelling shows that the continental crust has
been highly stretched and thinned in large parts of the southwestern Vøring Basin. Depth to basement
estimation suggests also that Triassic-Jurassic sediments are probably preserved on the Rån ridge, less
affected by the thinning process compared to the adjacent sub-basins. The modelling shows that the
Hevring sub-basin (as newly defined in this report) represents one of the thinnest crustal segments of the
Vigrid Syncline. To explain the apparent lack of classic rotated fault blocks in the Vigrid Syncline and
Hevring sub-basin, a decoupled model suggesting crustal boudinage is proposed to explain the evolution
of the Rån ridge. The LCB often coincides with the crustal raft and/or 'boudin' as modelled at the present
day. 3D seismics on the Rån ridge also show that deep lower-crustal bodies (LCB) already controlled the
structural style in the early rifting stage of the rifted margin and before the onset of more drastic crustal
thinning expected in the Late Jurassic - Early Cretaceous. A distinct phase of mid. Cretaceous extension is
also recognised in the Rån basin. It preceded the Late Cretaceous-Paleocene event leading to breakup in
the outer part of the outer Vøring Basin. The Rån ridge seems to have not been affected by this last rifting
event. The high-density lower-crustal block underneath the Rån ridge most likely represents old remnants
of the original Caledonian crust.

Sandwaves are common on many continental shelves indicating erosion, transport and deposition of sand by bottom currents. Their dynamic nature means that they can pose challenges to seafloor installations such as pipelines and other constructions on the seafloor. For studies of pollution and seabed resources (biological and geological) it is necessary to know where erosion and seposition occur. Detailed observations and descriptions of sandwaves as well as correct interpretation of their sedimentary environment are of importance for both industry and government for management of the ocean areas.