Lithospheric Structure of the East European Craton at the Transition from Sarmatia to Fennoscandia Interpreted from the TTZ-South Seismic Profile (SE Poland to Ukraine)

Abstract

The TTZ-South seismic profile follows the Teisseyre–Tornquist Zone (TTZ) at the SW margin of the East European Craton (EEC). Investigation results reveal the upper lithospheric structure as representing the NW-vergent, NE-SW striking overthrust-type, Paleoproterozoic (~1.84–1.8 Ga) Fennoscandia-Sarmatia suture. The Sarmatian segment of the EEC comprises two crustal-scale tectonic thrust slices: the Moldavo-Podolian and Lublino-Volhynian basement units, overriding the northerly located Lysogoro-Radomian unit of Fennoscandian affinity. The combined results of the TTZ-South and other nearby deep seismic profiles are consistent with a continuation of the EEC cratonic basement across the TTZ to the SW and its plunging into the deep substratum of the adjacent Paleozoic platform. Extensional deformation responsible for the formation of the mid to late Proterozoic (~1.4–0.6 Ga), SW-NE trending Orsha-Volhynia rift basin is probably also recorded. The thick Ediacaran succession deposited in the rift was later tectonically thickened due to Variscan deformation. The Moho depth varies between 37 and 49 km, resulting in the thinnest crust in the SE, sharp depth changes across the TTZ, and slow shallowing from 49 to 43 km to the NW. The abrupt Moho depth increase from 43 to 49 km is considered to reflect the overlying lower crust tectonic duplication within the suture zone.

Proposal for the Preparation of New Building Standards in Poland to Protect against Earthquakes in the Next 50 Years

“…This zone was formed more than 2 billion years ago when it met the three central tectonic provinces of Europe, known as the Paleoproterozoic East European Craton (EEC); the Paleozoic Platform of Central and Western Europe (PP), represented by its TESZ (Trans-European Suture Zone; Domain); and the Meso-Cenozoic Carpathian fragment of the vast Alpine-Himalayan organic system. In places of contact with the Vrancea seismic zone mentioned above and the Teisseyre-Tornquist zone (TTZ), which runs through the whole of Poland (Figure 11), western Ukraine, and Moldova, from the Baltic Sea to the Black Sea, Figure 12 [45]. The maps in Figures 6 and 7 do not include countries outside the European Union.…”

“…Therefore, the seismic hazard map for the entire Carpathian macroregion of Moldova and Ukraine in Figures 13 and 14 is worth mentioning. It shows that the Carpathian arc is threatened by earthquakes [45,47,48]. Furthermore, it is crucial because the Carpathian arc is located in Romania, Ukraine, Slovakia, Czech Republic, and Poland, see Figure 10.…”