Along-strike variations in rifted margin crustal architecture and lithosphere thinning between northern Voring and Lofoten margin segments off mid-Norway

An extensive geophysical and geological database is used to integrate observations and structural and stratigraphic modelling along the northern Voting and Lofoten margins. off mid-Norway. Subsidence and fault analysis demonstrates depth-dependent lithosphere stretching along both margin segments, and the modelling concurs with an emergent or relatively shallow-water emplacement environment for the breakup lavas along the northern Voting margin. However off Lofoten, subsidence modelling predicts similar to 1500 m of bathymetric relief during breakup in contradiction to the view of subaerial volcanic emplacement environment off mid-Norway. A distinct Early Eocene bathymetric gradient from Voting to Lofoten margin is suggested exhibiting depths in the order of 500-1000 m on the latter margin, and thus an environment for submarine lava emplacement. The water depth may even have reached similar to 1250 m following breakup due to an initial, rapid margin subsidence of the Lofoten margin along a deep-rooted low-angle detachment fault. The differences between northern Voting and Lofoten margin segments in pre- and post-breakup evolution are attributed to the Bivrost Lineament, a transfer zone separating the two margin segments, which appears as a major across-margin boundary in terms of margin physiography and paleogeography, differential sediment accommodation space, crustal- and lithosphere-scale structure, and breakup magmatism. Furthermore. gravity inversion results appear to independently predict a significantly greater volcanic addition on the Voting than on the Lofoten margin. (C) 2008 Elsevier B.V. All rights reserved.