Reconstruction of initial thickness and geometry of the Lower Palaeozoic strata in the Podlasie and Baltic basins, East European Craton

The aim of this study was to use the structural restoration technique to verify the correctness of the structural and palaeothickness maps created during the BLUE GAS Project. On the basis of well data as well as refined structural and palaeothickness maps of Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Penman, Triassic, Jurassic and Cretaceous horizons, a cross-section running across the Baltic Basin, the Mazury High and the Podlasie Basin was created. During the restoration process, the effects of compaction and fault activity were removed sequentially. The amount of erosion was estimated on the basis of the corrected palaeothickness maps. The resulting restoration is geologically reasonable and therefore both the structural and palaeothickness maps should be regarded as reliable. The reconstruction also allowed reproduction of the initial geometry and thickness of the Cambrian-Devonian strata and the recognition of three main episodes in the evolution of the sedimentary cover of this part of the East European Craton. The first episode was related to the deposition of the Lower Palaeozoic (up to the Lower Devonian) sedimentary complex on the relatively flat surface of the East European Craton edge. During the second episode, lasting most probably to the Permian, the Baltic and Podlasie Basins subsided significantly. The amount of subsidence was much higher in the Podlasie Basin. The third episode is related to the deposition of the almost flat-lying Mesozoic-Cainozoic complex.