Crustal structure beneath Lofoten, N. Norway, from vertical incidence and wide-angle seismic data

• Published in: Geophysical Journal International
• Main Authors: Mjelde, R., Sellevoll, M. A., Shimamura, H., Iwasaki, T., Kanazawa, T.
• Format: Text
• Language: English
• Published: Oxford University Press 1993
• Subjects: Articles; Lofoten; Norway; Røst; Northern Norway; Vestfjorden
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/114/1/116; https://doi.org/10.1111/j.1365-246X.1993.tb01471.x

A high-quality multichannel seismic reflection line was acquired in 1987 along a 175 km long profile across the continental shelf off Lofoten, northern Norway. A seismic wide-angle experiment was performed in 1988 along the same profile, using seven three-component Ocean Bottom Seismographs (OBS) with 20–25 km spacing and shotpoint intervals of 240 m. The study of the data has shown that the combination of the multichannel reflection and the wide-angle (OBS) technique provides information about the crustal structure beneath the Lofoten shelf that could not have been achieved using only one of the techniques. the multichannel reflection data provide a detailed image of the shallow (Cretaceous) structures, which represents an important basis for inversion of the OBS data. the lower crust and the Moho are also well mapped in some parts of the area with the multichannel reflection technique. The OBS data reveal that significant amounts of pre-Cretaceous sediments exist along almost the entire profile, with a maximum thickness of about 5 km in the Vestfjorden Basin. From the OBS data the thickness of the lower crust is inferred to decrease from about 11.5 km under the Røst High to about 2 km below the Lofoten Ridge. the OBS data indicate further that the Moho position under the Vestfjorden Basin is considerably deeper than can be inferred from the reflection data. About 10km below Moho a strong dipping event is observed in the OBS data. This upper mantle reflection might be related to a possible seaward dipping master fault, and/or presence of layers of partially hydrated peridotite.