Tectonic and bathymetric controls on stratigraphic sequences within evolving half-graben

Abstract

Abstract A modification of the domino fault block model is presented, which can be used to evaluate possible tectonic controls on the development of stratigraphic sequences within an evolving half-graben. The model allows average half-graben load to vary with time and allows the rate of faulting to be varied relative to any background component of basin subsidence. The basic domino model predicts only transgressive sequences at the crests of tilted fault blocks. It is found with the modified model that a decreasing average half-graben load (increasing bathymetry) or an increasing strain-rate may induce offlap and regression at the fault block crest. The model is used here successfully to model the syn-rift stratigraphy of a tilted fault block in the Viking Graben (North Sea). It is believed to have general implications for evaluating the syn-rift and early post-rift history of extensional basins. The internal geometry of condensed and unconformable sequences at fault block crests may lie below the limit of seismic resolution. This calls into question the ability of the seismic stratigraphic technique to address successfully the full history of an evolving half-graben.