Multi-Layered Evaporite Flow Induced by Thick-Skinned Deformation

Abstract

Three-dimensional seismic imaging combined with offshore well data analyses is used to interpret inverted faults underlying a thick Layered Evaporite Sequence in the Southern North Sea. By observing changes in evaporite volume above and away from an inversion structure, we infer that reactivation of thick-skinned normal faults induced multi-layered, trans-structural flow in the overlying evaporites. This flow acted to decouple deformation and prevent stress transmission from below to above the salt. The induced salt flow is layer-dependent, occurring mainly within the halite lithologies of the Layered Evaporite Sequence between a folded anhydrite stringer. This stringer folding predates inversion, which later induced stringer fold amplification and deflection nearer to the top of the evaporite sequence. These findings provide insights into the complexities of stratified evaporite rheologies and the timing of basin deformation, with wider implications for contractional salt tectonics wherever thick- and thin-skinned deformation may be coeval.