Mechanical aspects of pull-apart basins and push-up swells with applications to the Dead Sea transform

Pull-apart basins and push-up swells are common features at steps along strike-slip faults. The structure of these features is examined here for two types of rheology: perfect brittle and perfect ductile. The stress fields derived for the step area predict that fault patterns, mode of deformation and vertical displacement are different for the two rheologies. These predictions are illustrated for basins and swells developed in laboratory experiments with modelling materials. The structure of basins and swells along the Dead Sea transform is discussed here. The pull-apart basins display an intensively faulted southern end and a gently dipping flexure at the northern end. A consistent dissimilarity appears between the structures of the eastern and western boundary faults of the basins. According to the present interpretation, these dissimilarities reflect a relatively ductile crust in Arabia and a relatively brittle crust in Sinai-Israel.