Tectono-stratigraphic evolution of salt-influenced normal fault systems: an example from the Coffee-Soil Fault, Danish North Sea

Abstract

We explore how the relationships between fault activity, salt movement and sediment loading affect the stratal geometry of the hanging wall throughout the evolution of a salt-influenced normal fault system. We examine a c. 65 km long portion of the Coffee-Soil Fault System in the Danish North Sea, the hanging wall of which has been partially influenced by a pre-rift unit of mobile salt. To constrain the tectono-stratigraphic evolution of this fault system, we combine structural observations with seismic stratigraphic analysis of the hanging wall growth strata. We find that the hanging wall of the Coffee-Soil Fault System shows major depocentre shifts through time, along with marked variability in the along- and across-strike stratal geometries. We explain how the development of these characteristics is influenced by: (1) the segmentation and linkage history of the fault system; (2) the evolution of the salt-cored cover monoclines above blind basement fault segments; and (3) changes in the location and rate of accommodation generated by the load-driven withdrawal of salt up the dip-slope of the hanging wall and by fault-related subsidence. Our findings have implications for structural and stratigraphic studies in salt-influenced rift basins, as well as for understanding the potential distribution of geo-storage and hydrocarbon reservoirs in such settings.