Reply on RC1

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> The Barents Shear Margin separates the Svalbard and Barents Sea from the North Atlantic. It includes one northern (Hornsund Fault Zone) and a southern (Senja Fracture Zone) margin segment in which structuring was dominated by dextral shear. These segments are separated by the Vestbakken Volcanic Province that rests in a releasing bend position between the two. During the break-up of the North Atlantic the plate tectonic configuration was characterized by sequential dextral shear, extension, contraction and inversion. This generated a complex zone of deformation that contain several structural families of over-lapping and reactivated structures Although the convolute structural pattern associated with the Barents Shear Margin has been noted, it has not yet been explained in this framework. A series of crustal-scale analogue experiments, utilizing a scaled stratified sand-silicon polymer sequence, serve to study the structural evolution of the shear margin in response to shear deformation along a pre-defined boundary representing the geometry of the Barents Shear Margin and variations in kinematic boundary conditions of subsequent deformation events, i.e. direction of extension and inversion. The observations that are of particular significance for interpretating the structural configuration of the Barents Shear Margin are: 1) The experiments reproduced the geometry and positions of the major basins and relations between structural elements (fault and fold systems) as observed along and adjacent to the Barents Shear Margin. This supports the present structural model for the shear margin. 2) Several of the structural features that were initiated during the early (dextral shear) stage became overprinted and obliterated in the subsequent stages. 3) Prominent early-stage positive structural elements (e.g. folds, push-ups) interacted with younger (e.g. inversion) structures and contributed to a complex final structural pattern. 4) All master faults, pull-part basins and extensional shear duplexes initiated during the shear stage quickly became linked in the extension stage, generating a connected basin system along the entire shear margin at the stage of maximum extension. 5) The fold pattern generated during the terminal stage (contraction/inversion became dominant in the basinal areas and was characterized by fold axes with traces striking parallel to the basin margins. These folds, however, most strongly affected the shallow intra-basinal layers. This is in general agreement with observations in previous and new reflection seismic data from the Barents Shear Margin.