At many continental margins, di¡erential sediment loading on an underlying salt layer drives salt deformation and has a signi¢cant impact on the structural evolution of the basin.We use 2-D ¢niteelement modelling to investigate systems in which a linear viscous salt layer underlies a frictionalplastic overburden of laterally varying thickness. In these systems, di¡erential pressure induces the £ow of viscous salt, and the overburden experiences updip deviatoric tension and downdip compression. A thin-sheet analytical stability criterion for the system is derived and is used to predict conditions under which the sedimentary overburden will be unstable and fail, and to estimate the initial velocities of the system.The analytical predictions are in acceptable agreement with initial velocity patterns of the numerical models.In addition to initial stability analyses, the numerical model is used to investigate the subsequent ¢nite deformation. As the systems evolve, overburden extension and salt diapirism occur in the landward section and contractional structures develop in the seaward section.The system evolution depends on the relative widths of the salt basin and the length scale of the overburden thickness variation. In narrow salt basins, overburden deformation is localised and characterised by high strain rates, which cause the system to reach a gravitational equilibrium and salt movement to cease earlier than for wide salt basins. Sedimentation enhances salt evacuation by maintaining a di¡erential pressure in the salt. Continued sedimentary ¢lling of landward extensional basins suppresses landward salt diapirism. Sediment progradation leads to seaward propagation of the landward extensional structures and depocentres. At slow sediment progradation rates, the viscous £ow can be faster than the sediment progradation, leading to e⁄cient salt evacuation and salt weld formation beneath the landward section. Fast sediment progradation suppresses the viscous £ow, leaving salt pillows beneath the prograding wedge.

We investigate the evolution of passive continental margin sedimentary basins that contain salt through two -dimensional (2D) analytical failure analysis and plane-strain ¢nite-element modelling. We expand an earlier analytical failure analysis of a sedimentary basin/salt system at a passive continental margin to include the e¡ects of submarine water loading and pore £uid pressure. Seaward thinning sediments above a weak salt layer produce a pressure gradient that induces Poiseuille £ow in the viscous salt.We determine the circumstances under which failure at the head and toe of the frictional^plastic sediment wedge occurs, resulting in translation of the wedge, landward extension and seaward contraction, accompanied by Couette £ow in the underlying salt.The e¡ects of water: (i) increase solid and £uid pressures in the sediments; (ii) reduce the head to toe di¡erential pressure in the salt and (iii) act as a buttress to oppose failure and translation of the sediment wedge.The magnitude of the translation velocity upon failure is reduced by the e¡ects of water.The subsequent deformation is investigated using a 2D ¢nite-element model that includes the e¡ects of the submarine setting and hydrostatic pore pressures.The model quantitatively simulates a 2D approximation of the evolution of natural sedimentary basins on continental margins that are formed above salt. Sediment progradation above a viscous salt layer results in formation of landward extensional basins and listric normal growth faults as well as seaward contraction. At a later stage, an allochthonous salt nappe overthrusts the autochthonous limit of the salt.The nature and distribution of major structures depends on the sediment properties and the sedimentation pattern. Strain weakening of sediment favours landward listric growth faults with formation of asymmetric extensional depocentres. Episodes of low sediment in£ux, with partial in¢ll of depocentres, produce local pressure gradients in the salt that result in diapirism. Diapirs grow passively during sediment aggradation.

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The Mid‐Palaeocene palaeogeography of Denmark and the surrounding areas have been reconstructed on the basis of published geological data integrated with 3D geodynamic modelling. The use of numerical modelling enables quantitative testing of scenarios based on geological input alone and thus helps constrain likely palaeo‐water depths in areas where the geological data are inconclusive or incomplete. The interpretation of large‐scale erosional valleys and small‐scale circular depressions at the Mid‐Palaeocene Top Chalk surface in the Norwegian–Danish basin as either submarine or subaerial features is enigmatic and has strong implications for palaeogeographical reconstructions of the eastern North Sea basin. A 3D thermo‐mechanical model is employed in order to constrain the likely palaeo‐water depths of the eastern North Sea basin during the Palaeocene. The model treats the lithosphere as an elasto‐visco‐plastic continuum and models the lithospheric response to the regional stress field and thermal structure. The model includes the effects of sea‐level change, sedimentation and erosion, from the Mid Cretaceous to the present. Modelling results reproduce to first order geological data such as present sediment isopachs and palaeo‐water depths. It is concluded that the Mid Palaeocene water depths in the Norwegian–Danish basin were about 250 m. The erosional valleys and circular depressions at the top of the Upper Cretaceous‐Danian Chalk Group are thus interpreted to have formed in relatively deep water rather than due to subaerial exposure. Likely interpretations of the structures are therefore submarine valleys and pockmarks.