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

Abstract

AbstractTo understand the major structural features of the sedimentary cover and crystalline crust of the Lofoten‐Vesterålen margin and the northern part of the Vøring segment of the Mid‐Norwegian continental margin, a lithosphere‐scale 3‐D 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 Røst Basins and the northern parts of the Vøring Basin and Trøndelag Platform. All available published and/or released data have been used to set the initial 3‐D model which has been validated by means of 3‐D density forward modeling to obtain a gravity‐consistent 3‐D structural/density model. Results from the 3‐D density modeling reveal that relatively thick sedimentary rocks are present in the distal Røst 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 3‐D density modeling indicate the presence of an atypical low‐density lithospheric mantle beneath a large part of the Lofoten‐Vesterålen 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‐Vesterålen segment from the Vøring margin showing contrasting densities and crustal thicknesses.