ADVANCEMENTS IN RECOGNITION OF THE STRUCTURE AND PHANEROZOIC TECTONO-SEDIMENTARY EVOLUTION OF THE EAST EUROPEAN CRATON IN POLAND REVEALED BY RECENT REGIONAL SEISMIC DATA

The western edge of the East European Craton (EEC) in Poland is limited to the southwest by the Teisseyre–Tornquist Zone (TTZ) that separates it from the Paleozoic Platform. During the Phanerozoic, this zone influenced the development of all major sedimentary basins in Poland. Seismic data from the recently acquired regional deep reflection survey, PolandSPAN integrated with other new and archive seismic data, revealed many new tectonic features of the cratonic margin in Poland, allowing for a better understanding of its complex tectono-sedimentary history. The Cambrian - Lower Ordovician succession within the NW part of the study area (Baltic Basin) was deposited on the Baltica passive margin and is covered by the Upper Ordovician - Silurian succession of the Caledonian foredeep basin. The large-scale geometry of the Silurian sedimentary succession reflects progressive progradation of the foredeep infill towards the E-SE. The Silurian erosional top is covered by Permian to Cretaceous sedimentary cover deposited within the NE flank of the Mid-Polish Trough (MPT), a sedimentary basin that developed above the TTZ. Widespread Late Triassic normal and reverse faulting that affects the cratonic edge has been also documented in the Baltic Basin. This faulting can be correlated with tectonic activity within the axial part of the MPT that was associated with the first significant salt movements. Seismic data from the SE part of the study area (Lublin Basin; LB) has shown for the first time the deep structure of its axial part, including the Moho discontinuity, laminated lower crust, crystalline basement and sedimentary cover. Continuous top-EEC basement was shown to continuously descend from ~2 km in the NE to ~20 km in the SW, beneath the Radom-Krasnik Block (RKB). The RKB and LB represent a NE-vergent thin-skinned Variscan (Late Carboniferous) system thrust toward the EEC. The RKB is a thrust stack that imbricates a 10-12 km thick pile of ?Neoproterozoic to Devonian sediments. Some of Variscan compressional structures were reactivated during the Late Cretaceous inversion of the Mid-Polish Trough. Finally, the deep structure of the Grojec fault zone, an important SW-NE strike-slip fault zone, has also been revealed by the data, demonstrating its relationship with Paleozoic and Mesozoic-Paleogene tectonic activity.