EGU2020-7687
https://doi.org/10.5194/egusphere-egu2020-7687
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The transition of the East European cratonic lithosphere to that of the Palaeozoic collage of the Trans-European Suture Zone as depicted on the TTZ-South deep seismic profile (SE Poland to NW Ukraine)

Tomasz Janik1, Vitaly Starostenko2, Paweł Aleksandrowski3, Tamara Yegorova2, Wojciech Czuba1, Piotr Środa1, Anna Murovskaya2, Khrystyna Zajats4, Andrzej Głuszyński5, Katerina Kolomiyets2, Dmytro Lysynchuk2, Dariusz Wójcik1, Victor Omelchenko2, Olga Legostaieva2, James Mechie6, Anatoly Tolkunov7, Tatiana Amashukeli2, Dmytro Gryn’2, and Serhii Chulkov2
Tomasz Janik et al.
  • 1Institute of Geophysics, Polish Academy of Sciences, Ks. Janusza 64, PL-01-452 Warszawa, Poland
  • 2Institute of Geophysics, National Academy of Sciences of Ukraine, Palladin Av. 32, 03680 Kiev, Ukraine
  • 3Polish Geological Institute-National Research Institute, Lower Silesia Branch, Jaworowa 19, 53-122 Wrocław, Poland
  • 4Zakhidnadra Servis, Sichovykh Striltsiv 12/9, Lviv, Ukraine
  • 5Polish Geological Institute-National Research Institute, Rakowiecka 4, PL-00-975 Warszawa, Poland
  • 6Deutsches GeoForschungsZentrum – GFZ, Section “Geophysical Deep Sounding”, Telegrafenberg 14473, Potsdam, Germany
  • 7State Geophysical Enterprise “Ukrgeofizika”, Sofii Perovskoy 10, 03057, Kiev, Ukraine

Crustal and uppermost mantle structure along the Teisseyre-Tornquist Zone (TTZ)  was explored along the ~550 km long, NW-SE-trending TTZ-South profile, using seismic wide-angle reflection/refraction (WARR) method. The profile line was intended to follow the border between the East European Craton (EEC) and the so called Palaeozoic Platform (PP) of north-central Europe, believed to contain a number of crustal blocks that were accreted to the craton during pre-late Carboniferous times, defining the Trans-European Suture Zone (TESZ).

The seismic velocity model of the TTZ-South profile shows lateral variations in crustal structure. Its Ukrainian segment crosses the interior of the Sarmatian segment of the EEC, where the crystalline basement gradually dips from ~2 km depth in the SE to ~12 km at the Ukrainian-Polish border. This part of the model shows a four-layered crustal structure, with an up to 15 km-thick sedimentary cover, an underlying crystalline upper crust, a 10-15 km-thick middle crust and a ~15 km thick lower crust. In Poland, the profile passes along the TESZ/EEC transition zone of complex crustal structure. The crystalline basement, whose top occurs at depths of 10-17 km, separates the sedimentary cover from the ~10 km thick mid-crustal layer (Vp=6.5-6.6 km/s), which, in turn, overlies a block of 10-15 km thickness with upper crustal velocities (Vp~6.2 km/s). The latter is underlain by a ~10-15 km-thick lower crust. Along most of the model one can see conspicuous velocity inversion zones occuring at various depths. At intersections of the TTZ-South profile with some previous deep seismic profiles (e.g. CEL02, CEL05, CEL14, PANCAKE) such inversions document complex wedging relationships between the EEC and PP crustal units. These may have resulted from tectonic compression and thick-skinned thrusting due to either Neoproterozoic EEC collision with accreting terranes or intense Variscan orogenic events. Five high velocity bodies (HVB; Vp = 6.85-7.2 km/s) were detected in the middle and lower crust at 15-37 km depth. The Moho depth varies substantially along the profile. It is at ~42 km depth in the NW and deepens SE-ward to ~50 km at ~685 km. Subsequently, it rises abruptly to ~43 km at the border of the Sarmatian segment of the EEC and sinks again to ~50 km beneath the Lviv Paleozoic trough at ~785 km. From this point until the SE end of the profile, the Moho gently shallows, up to a depth of ~37 km, including a step-like jump of 2 km at ~875 km. Such abrupt Moho steps may be related to crust-scale strike-slip faults. Along the whole profile, sub-Moho velocities are ~8.05-8.1 km/s, and at depths of 57-63 km Vp values reach 8.2-8.25 km/s. Four reflectors/refractors were modelled in the upper mantle at ~57-65 km and ~80 km depths.

How to cite: Janik, T., Starostenko, V., Aleksandrowski, P., Yegorova, T., Czuba, W., Środa, P., Murovskaya, A., Zajats, K., Głuszyński, A., Kolomiyets, K., Lysynchuk, D., Wójcik, D., Omelchenko, V., Legostaieva, O., Mechie, J., Tolkunov, A., Amashukeli, T., Gryn’, D., and Chulkov, S.: The transition of the East European cratonic lithosphere to that of the Palaeozoic collage of the Trans-European Suture Zone as depicted on the TTZ-South deep seismic profile (SE Poland to NW Ukraine), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7687, https://doi.org/10.5194/egusphere-egu2020-7687, 2020