Regional tectonic interpretation of image enhanced gravity and magnetic data covering the mid-Norwegian shelf and adjacent mainland
1999; Elsevier BV; Volume: 306; Issue: 2 Linguagem: Inglês
10.1016/s0040-1951(99)00057-8
ISSN1879-3266
AutoresChristine Fichler, Egil Rundhovde, Odleiv Olesen, B. Saether, Håkon Rueslåtten, Erik Lundin, A. G. Doré,
Tópico(s)earthquake and tectonic studies
ResumoGravity and magnetic field data covering mid-Norway and the Norwegian Sea were processed in order to enhance tectonic features on various scales. The local features were subjected to an unconventional processing technique involving a non-linear, adaptive Wallis filter designed to enhance the smallest wave lengths. When compared with recent structural information derived from seismic data, the processed gravity and magnetic maps show the main structural trends, major fault zones and basin boundaries, thus proving their worth for regional tectonic mapping. Previously undetected NW–SE-trending offshore crustal lineaments are revealed. A landward prolongation of the Bivrost Lineament appears to continue subparallel towards Proterozoic shear zones below the Caledonian nappes in the Rana area, either along the western margin of the Transscandinavian Granite–Porphyry Belt or the NW–SE-trending Malå–Skellefteå Tectonic Zone. A large lineament is also observed as a landward prolongation of the Surt Lineament indicating a relationship with the Storsjön–Edsbyn Deformation Zone, a major, deep, crustal shear zone in the Precambrian of Sweden. A slightly increased seismic activity, which is possibly related to the present ridge push force, is observed along parts of the previously unknown transfer zones. Combined gravity and magnetic modelling indicates a low crustal thickness in the northwesternmost part of the Vøring Basin, between the Surt and the Jan Mayen Lineaments. The lack of correlation between the gravity and the magnetic patterns observed on the residual field maps suggests the presence of a shallow Curie isotherm situated above or within the uppermost basement.
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