The North Sea Revisited: New Insights into Normal Fault Activity in the North Viking Graben and Its Generic Implications for Rift System Evolution

Gill, Caroline E., John R. Underhill, Patience A. Cowie, University of Edinburgh, Edinbugh, United Kingdom

Extensional fault growth and linkage plays an important role in the development of rift sys­tems. Recent field studies (e.g. Gulf of Corinth, Gulf of Suez) have highlighted the main con­trols on structural styles and their effects on the temporal and spatial evolution of basin phys­iography, stratigraphic geometries and sediment dispersal pathways in rift basins. However, little application of these controls has been made to analogous subsurface examples.

Interpretation of well-calibrated seismic data from the East Shetland Basin allows us to challenge the traditional view that all faults in the Northern North Sea were active through­out the Late Jurassic rift episode. Instead, a new interpretation demonstrates that the locus of extension migrated east towards the Viking Graben with the latest primary motion occur­ring on the graben bounding fault itself. The effect of strain localisation towards the basin centre with time led to passive rotation of earlier (more westerly) structures (e.g. Snorre) and their depocentres.

The timing of movement on major faults had a profound effect on the relative distribu­tion of depocentres, source areas and sediment pathways throughout the syn-rift interval.

This work in the North Sea, with its extensive and high-quality dataset forms a vital com­ponent in the advancement of our understanding of the structural evolution of rift basins. Application of models of strain localisation to basins where data is more limited may aid understanding of these areas and provide more clues in the deliberate search for subtle hydrocarbon traps.