Paleostresses of the Groningen area, the Netherlands—Results of a seismic based structural reconstruction

We describe a novel workflow to reconstruct paleostresses in the subsurface where the traditional outcrop-based method that uses fault slip measurements is not possible. We use 3D seismic data and structural restoration to determine fault surfaces and slip vectors. These data are then used as input for paleostress-reconstruction algorithms.The study area of ca. 750 km2 is situated in the Groningen Block, the Netherlands. Excellent quality 3D seismic data were used to interpret 11 horizons and approximately 80 faults between the Tertiary and the Top Rotliegend. Indicators of fault slip direction are fault undulations, sedimentary structures offset by faults and shapes of horizon cut-outs. These indicators were used as a basis of 3D restoration of the interpreted horizons. A stepwise restoration approach was chosen that removed younger deformation to obtain slip vectors for older deformation events. In a following work step, Numeric Dynamic Analysis (NDA) was used to calculate paleostress tensors for the Middle and Lower Tertiary, Upper Cretaceous and Upper Rotliegend sequences.The results presented in this paper are consistent with existing paleostress interpretations for NW Europe; however, in contrast to previous studies they are derived from a subsurface volume where paleostress information was lacking until now. Issues that need further study include the effect of the size of the study area on the assumptions of a homogenous stress field, and an analysis of the ambiguity of the interpretation of fault slip indicators on 3D seismic data.