Structural modelling of regional depth profiles in the Vøring Basin: implications for the structural and stratigraphic development of the Norwegian passive margin

Abstract

Interpretation of key regional seismic lines across the Vøring Basin has identified a number of seismic megasequences that have provided a framework for further basin analysis. These megasequences have been classified as pre-, syn- and post-rift with respect to the late Cretaceous-early Tertiary phase of extension. Forward and reverse structural and stratigraphic modelling of two of these regional lines has been performed in an attempt to test and validate the structural and stratigraphic interpretations of the syn and post-rift megasequences. Reverse thermal subsidence modelling (flexural backstripping) of these lines to the base Tertiary was performed using a laterally varying beta factor across the sections. A number of features on each of the depth profiles are considered to be regional subaerial datums for the backstripped sections. The backstripped templates were then forward modelled using the flexural cantilever model. The forward models calculate a laterally varying beta profile along their length which can be compared to the reverse models, thereby ensuring an internally consistent structural model between both the reverse and forward modelling techniques. The modelling work has highlighted the existence of a significant discrepancy between the extension measured from the forward models (fault heaves) and the extension needed to produce geologically-acceptable backstripped profiles. This observation is of particular importance as it may place a significant constraint on the mode of lithospheric extension that can be used to explain the evolution of the Norwegian continental margin.