Salt Tectonics of the Subhercynian Basin, Northern Germany - From Paleostress Field Analysis to Basin Modelling

Salt dominated sedimentary basins are economically important, because they can have a high hydrocarbon potential. We used the Subhercynian Basin in northern Germany as a natural laboratory to analyse the evolution of piercing and non-piercing salt structures. Paleostress field reconstructions were carried out to analyse stress field perturbations in the vicinity of the salt structures. It became evident that even low amplitude salt pillows show a rotation of the horizontal compressional paleostress vector for up to 90°. This perturbation is predictable because the horizontal compressional paleostress vector is always perpendicular to the outline of the salt pillow. A numerical basin modelling study was carried out for a rim syncline of the Helmstedt-Staßfurt salt wall to analyse the salt wall evolution. The extracted burial history curve showed that initial subsidence was rapid and later strongly decreased due to depletion of the salt layer. This is probably a general subsidence pattern of salt rim synclines. The tectonic analysis of the Subhercynian Basin implies that the evolution of the Helmstedt-Staßfurt salt wall can be subdivided into the three stages reactive, active and passive diapirism.