Advancements in Interpretation of the Tectonic Structure of the East European Cratonic Edge in Poland Revealed by Recent Regional Seismic Data — Two Orogenies and Beyond

Krzywiec, Piotr; Lis, Pawel; Buffenmyer, Vinton; Malinowski, Michal; Lewandowski, Marek

The western edge of the East European Craton in Poland, which has recently been the focus of exploration for unconventional hydrocarbons, is limited to the west by the Teisseyre - Tornquist Zone (TTZ) that separates it from the Paleozoic Platform. During Paleozoic to Cenozoic times, this zone influenced the development of sedimentary basins in Poland, including those that overlie the cratonic edge. Seismic data from the recently acquired high-effort regional deep reflection survey, PolandSPAN, revealed many new tectonic features of the cratonic edge in Poland, allowing for a better understanding of its complex tectono-sedimentary history. The Cambrian - Lower Ordovician succession within the northwestern part of the study area was deposited on the Baltica passive margin and is covered by the Upper Ordovician - Silurian succession of the Caledonide 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. Newly acquired seismic data revealed widespread Late Triassic normal faulting affecting the cratonic edge, including its Lower Paleozoic cover. This faulting, hitherto not documented, 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 Lublin basin located in SE Poland has shown for the first time the deep structure of its axial part, including the Moho discontinuity, laminated lower crust, crystalline basement and the Cambrian to Lower Silurian sedimentary cover. Increased thickness of the Cambrian - Ordovician sediments within the axial and western part of the basin could be possibly attributed to Caledonian thrusting. Late Carboniferous Variscan compressional structures are partly rooted in the crystalline basement and are accompanied by thick-skinned structures. Inversion structures responsible for Late Cretaceous - Paleogene uplift of the SE part of the study area have been proven to be deeply rooted and related to some strike-slip movements. 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.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013