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Strefa Teisseyre’a-Tornquista : dawne koncepcje a nowe dane

Narkiewicz Marek, Petecki Zdzisław

Przegląd Geologiczny

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2019

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Vol. 67, nr 10

837--848

EN

Concepts prevailing among the Polish geoscientists during the last decades assumed that the Teisseyre-Tornquist Zone is a major tectonic discontinuity separating the pre-Ediacaran East European Craton (EEC) crust from the Paleozoic Platform composed of terranes accreted during the Caledonian and Variscan orogenic processes. The recent interpretations of the TTZ by Mazur and collaborators, basedon gravity modelling and new PolandSPAN seismic reflection data, revive earlier ideas of the EEC crust extending to the western Poland and NE Germany. These authors propose that the TTZ is in fact a Sveconorwegian (ca. 1 Ga old) collisional suture marked by a crustal keel expressed as the Pomeranian and Kuiavian gravity lows in northern and central Poland. However, the present review of seismic data available, as well as a closer evaluation of the modelling results, do not confirm the keel/suture concept. On the other hand, the idea of the TTZ as an Early Paleozoic tectonic discontinuity is supported by several lines of evidence, including a strong regional magnetic gradient and a contrast in the crustal structure. The latter is revealed by seismic velocity distribution from the refraction data, in the results of magnetotelluric profiling and in recent seismicity patterns. The interpretation of the PolandSPAN data attempting to prove the continuity of the cratonic crust and its Ediacaran-Lower Paleozoic cover across the TTZ appears questionable. At the same time the POLCRUST-01 deep seismic profile in SE Poland documents that the zone is associated with the subvertical Tomaszów Fault. The basement top displacement by ca. 0,5 km and associated change in its slope are related to the fault whose deep crustal roots are further documented by reflectivity patterns in the lower crust. The recent modelling exercise by Krzywiec and collaborators aimed at questioning the thick-skinned nature of this fault does not present compelling results, being based on a poorly constrained geological model. The general conclusion from the present review is that the recently published data either support or at least do not contradict the concept of the TTZ as a tectonic zone separating the continuous EEC crust from several allochtonous blocks - mostly proximal Early Paleozoic terranes to the south-west. Thelithospheric memory of the TTZ echoed in successive stages of its reactivation in different intra-plate tectonic regimes - transpressive Variscan, mostly extensional or transtensional Permian through Early Cretaceous, compressional Late Cretaceous and finally Neogene, related to the Carpathian orogenic compression.

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Relations between present relief on the border of lowlands and highlands and geological structures of the Paleozoic Platform – a case study from central Poland

Szmidt Aleksander, Wachecka-Kotkowska Lucyna

Geology, Geophysics and Environment

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2019

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Vol. 45, no. 1

57--70

EN

The article is an attempt to find relations between geology and the dynamics of the Mesozoic surface of the Łódź Synclinorium, the Radomsko Elevation and the Bełchatów Graben and the present relief on the border of the Polish Lowlands and Uplands in its central part. Fossil relief has been compared with the present one as related to the extent of the recession phases of the Saalian (Wartanian) ice-sheet. A significant convergence has been found between the Mesozoic surface plain and the main morphologic elements. The role of elevations and fossil valleys has been stressed as stable forms in the pre-Pleistocene and contemporary landscape. Also stressed has been the meaning of grabens and elevations enforcing longer stoppages of the Wartanian stadial of the Middle Polish Glaciations.

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Basement structure of the Paleozoic Platform in Poland

Narkiewicz M., Petecki Z.

Geological Quarterly

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2017

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Vol. 61, No. 2

502--520

EN

The Paleozoic Platform comprises the southwestern half of the Polish territory, separated from the Precambrian East European Platform (EEP) by a NW–SE trending subvertical lithospheric-scale discontinuity – the Teisseyre-Tornquist Zone. In the present study, the Paleozoic Platform basement is subdivided based on geological and geophysical evidence acquired during the last decades, including deep seismic refraction and reflection results, as well as gravity, magnetic and magnetotelluric data. The units adjacent to the EEP, the Mid-Polish Domain (comprising the Łysogóry Block) and the Pomeranian Block, are characterized by a thinned three-layer EEP-type crystalline crust (age 1.7–3.7 Gy). Their oldest platform cover is probably composed of thick Ediacaran syn-rift sedimentary and volcanic rocks. Their western extension in the contiguous German and Baltic area can be traced as far as the East Elbian Massif and Thor Suture based mainly on magnetic anomaly patterns. The Upper Silesian and Małopolska blocks located in SE Poland are characterized by Cadomian (660–600 My) basement overlain by the thick deformed Ediacaran foredeep deposits. Whereas the units with the EEP-type basement are interpreted as proximal terranes displaced along the EEP margin during the late Early Paleozoic, the blocks with a Cadomian basement are conceived as exotic terranes of a possible Gondwanan provenance. All these terranes were accreted ultimately during the final, latest Silurian stages of the Caledonian deformation although the exact scenario of the amalgamation remains hypothetical. The Sudetic Domain in SW Poland is a collage of different crustal units juxtaposed ultimately in the Pennsylvanian (ca. 310 Ma) during the final episodes of the Variscan Orogeny. Their northern boundary corresponds to the Rheic Suture traceable in magnetic and gravity anomalies pattern along the northern margin of the Wolsztyn–Leszno High, and continuing westwards along the Mid-German Crystalline High. The arcuate trace of the suture in the NE is dextrally displaced along the Odra Fault, and continues southwards where it is mapped as the Moravian–Silesian Suture.