Deep structure of the Lofoten‐Vesterålen segment of the Mid‐Norwegian continental margin and adjacent areas derived from 3D density modeling

To understand the major structural features of the sedimentary cover and crystalline crust of the Lofoten-Vesteralen margin and the northern part of the Voring segment of the Mid-Norwegian continental margin, a lithosphere-scale 3D structural model has been constructed. This model extends from the exposed crystalline rocks of the Fennoscandian Shield in the east to the Cenozoic oceanic domain of the Norwegian-Greenland Sea in the west, covering the Vestfjorden, Ribban and Rost basins and the northern parts of the Voring Basin and Trondelag Platform. All available published and/or released data have been used to set the initial 3D model which has been validated by means of 3D density forward modeling to obtain a gravity-consistent 3D structural/density model. Results from the 3D density modeling reveal that relatively thick sedimentary rocks are present in the distal Rost Basin below the lava flows. The presence of a low-density more than 20-km thick granitic body has been modeled within the middle-upper crystalline crust beneath the eastern part of the Vestfjorden Basin and the adjacent mainland. Moreover, the results of the 3D density modeling indicate the presence of an atypical low-density lithospheric mantle beneath a large part of the Lofoten-Vesteralen margin which is required to fit the regional component of the modeled gravity with the observed one. The pronounced crustal feature within the model area is the Bivrost Lineament that appears to be the deeply-seated lithosphere-scale boundary that delineates clearly the Lofoten-Vesteralen segment from the Voring margin showing contrasting densities and crustal thicknesses.