Variscan deformation along the Teisseyre-Tornquist Zone in SE Poland: Thick-skinned structural inheritance or thin-skinned thrusting?

• Published in: Tectonophysics 2017-10, Vol.718, p.83-91
• Main Authors: Krzywiec, P., Gągała, Ł., Mazur, S., Słonka, Ł., Kufrasa, M., Malinowski, M., Pietsch, K., Golonka, J.
• Format: Article
• Language: English
• Subjects: Carboniferous; Cratons; Data acquisition; Deformation; Deformation mechanisms; Lublin Basin; Modelling; Ordovician; Palaeozoic; Permian; Piles; Plates (structural members); POLCRUST-01 deep seismic profile; Radom-Kraśnik Block; Restoration; Seismic activity; Seismic data; Seismic surveys; Seismological data; Seismology; Structural models; Surveying; Tectonic processes; Teisseyre-Tornquist Zone; Two dimensional models; Variscan tectonics
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2017.06.008

Recently acquired seismic reflection data provide better insight in the structural style of extensive sedimentary series overlying the SW slope of the East European Craton (EEC) in Poland. The two main seismic datasets – the POLCRUST-01 profile and PolandSPAN survey – yielded contrasting thick – and thin-skinned structural models for the same structural units in SE Poland. We reattempt an interpretation of the POLCRUST-01 profile using techniques of cross-section balancing and restoration aided by 2D forward seismic modelling. An outcome is the thin-skinned structural model is. This solution relies on a continuous top of the EEC crystalline basement well represented in the seismic data as well as on fragmentary, yet conclusive seismic geometries in shallow depth intervals proving the Ediacaran-Palaeozoic series to be thrust and folded. A Variscan (late Carboniferous) compressional regime is consequently invoked to explain thin-skinned structuring of the pre-Permian sedimentary pile and >20km of calculated shortening. We demonstrate an ambiguous nature of the top-basement irregularities previously used as indicators of basement-rooted vertical faulting. The tilt and abrupt increase of the top-basement taper under the thin-skinned belt are attributed to pre-Ordovician tectonic processes operating along the SW margin of the EEC. Post-rift subsidence and/or flexural loading giving rise to a broken foreland plate are invoked. •2D seismic data confirm show that pre-Permian sediments covering TTZ in SE Poland are included in fold-and-thrust belt.•Variscan shortening is invoked to explain last stage of thin-skinned structuring of these strata.•Late Palaeozoic thick-skinned reactivation of the TTZ is disproved.