Three-dimensional retro-modelling of transpression on a linked fault system: the Upper Cretaceous deformation on the western border of the Bohemian Massif, Germany

Abstract The Zone of Erbendorf-Vohenstrauß (ZEV) on the western margin of the Bohemian Massif was deformed by an Upper Cretaceous intra-plate deformation event. Dextral transpression was caused by the reactivation of pre-existing structures. Using the extensive geological database available, we have constructed a three-dimensional virtual model of the ZEV. The model was deformed in reverse, to remove the effects of the Upper Cretaceous event. This involved moving the hanging wall (the ZEV) in a sinistral transtensive sense northwards above a composite active fault surface composed of two steep faults, perpendicular to each other in strike, and a detachment intersecting both faults at 9.5 km depth. Hanging-wall deformation was accommodated by antithetic inclined shear. Seven kilometres heave of the hanging wall fulfilled the geological constraints. Calculated uplifts range from 2 to 6 km. Deformation is mostly only contained within the ZEV. The hanging-wall deformation above a linked fault system was highly complex, causing rollover above one fault and drag-folding above the other. The most important control on the vertical movement and deformation of the hanging wall was a 30° change in the strike of one of the coupled faults.