The Halten Terrace is located on the mid-Norwegian rifted margin and is bounded by basin bounding normal faults. On the eastern side, the Bremstein and Vingleia Fault Complexes (BVFC) constitute the most significant normal faults responsible for tectonic control on adjacent hanging wall depocenters. On the western side, the N-S oriented Klakk Fault Complex is the major structural feature. On the rifted margin the BFVC lies in the necking domain where propagation of these faults and their geometry have profound effects on thehanging wall basin shape thus on the sedimentation in those basins.
In this study, 3D and 2D seismic reflection data and available well data were used to interpret the seismic sections and to map the geometry of BVFC and adjacent Jurassic and Early Cretaceous hanging wall depocenters. To study the evolution of the BVFC and their effect on sediments in the Middle Jurassic to Early Cretaceous, study area was divided into three main segments. Four main key profiles were selected, covering the BVFC and adjacent depocenters. The syn- and post-rift megasequences were interpreted where theTop of the Garn formation marks the base of syn-rift, Top Spekk is base of post-rift with Top of Lange formation interpreted as the upper horizon of the post-rift sediments. Time structure maps of these horizons were created to provide the depocenter geometries and to use them for depth conversion. A velocity model was constructed where the velocity values was extracted from the checkshot data of the available wells. In result thickness maps were constructed to give an overview of the spatial distribution and thickness variations of the sediments in the hanging wall depocenters of the master fault. The presence of salt was confirmed by wells in the study area, and its role in the tectonic activity is also briefly discussed in this study.
We document an along-strike variation in the geometry of the primary faults, in the north, the main strand of the BVFC behaves like a more or less Planar normal fault and is associated with regional monocline folding due to its behavior as a blind fault in some parts. In contrast, in the central region, the fault geometry is ramp flat ramp, and in the south, the main strand of the BVFC behaves as a Listric normal fault. Master fault evolution as major rift associated fault and its effects on the adjacent hanging wall depocenters are interpreted. Basin geometry in the hanging wall changes with the geometry of the fault, in northern section there was a regional syncline shaped basin, while in the central part accommodation space was covered by the syncline-anticline pair and in southern part of the study area, hanging wall basin was shaped more like the half graben basin. In the study area syn-rift deposition was greater in the north. While in the central and western part, syn-rift deposition was wedge shaped which means the thickness is greater close to faultand decreases on moving away from fault. This thickness variation provides the spatial distribution of the syn and post-rift sediments in the study area.