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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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Paleogene-Neogene tectonic evolution of the lignite-rich Szamotuły Graben

Widera Marek, Stawikowski Wojciech, Uścinowicz Grzegorz

Acta Geologica Polonica

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2019

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Vol. 69, no. 3

387--401

EN

The Szamotuły Graben covers the southernmost part of the Permo-Mesozoic Poznań–Szamotuły Fault Zone. Along this regional discontinuity there are several salt structures, including the Szamotuły diapir, over which an extensional graben formed in the Paleogene and Neogene. The graben is located north of Poznań in central-western Poland, and is NW–SE-trending, ~20 km long, 3–5.5 km wide, and up to 160 m deep. It is filled with Lower Oligocene and Neogene sediments, including relatively thick lignite seams. Data from boreholes allow the assignment of the graben-fill sediments to appropriate lithostratigraphic units. Furthermore, analysis of changes in the thickness of these units provides evidence for periods of accelerated graben subsidence or uplift relative to its flanks. As a result, two distinct stages of tectonic subsidence and one inversion in the Paleogene–Neogene evolution of the Szamotuły Graben have been distinguished. Thus, relatively significant subsidence occurred in the Early Oligocene and the middle Early–earliest Mid-Miocene, while slight inversion took place in the middle part of the Mid-Miocene.

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O nowych rozwiązaniach tektonicznych w „Atlasie geologicznym Polski”

Aleksandrowski P., Mazur S.

Przegląd Geologiczny

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2017

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Vol. 65, nr 12

1499--1510

EN

Authorial comprehensive comments and explanations are given to some of the interpretations applied in the tectonic part of the newly published Geological Atlas of Poland (Nawrocki, Becker, 2017) that considerably change the hitherto generally accepted concepts. It should be, however, admitted that most of those "new’" solutions were already proposed in the past by other workers as hypotheses that could not have been tested in the then state of knowledge on Poland’s deep geology and scientific tools at hand. This has now changed with abundant new data obtained with modern seismic techniques and advanced methods of potential field modelling. Using those data, we justify the reasons for, among others, a significant eastward shifting the front of the Variscan Orogen in Poland andfor the accompanying change in position of the division line between the Precambrian and Palaeozoic platforms. We also show the rationale for accepting a far-reaching southwestward extent of the East European Craton’s crystalline basement below the Palaeozoic Platform and for reinterpretation of the Teisseyre-Tornquist Zone’s nature, together with the question of early Palaeozoic terranes in the TESZ and the situation of the Caledonian foredeep at the SW margin of the East-European Craton.

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Anomalie magnetyczne i ich rola w rozpoznaniu struktury krystalicznego kompleksu skorupy ziemskiej południowo-wschodniej Polski

Grabowska T., Bojdys G., Petecki Z.

Biuletyn Państwowego Instytutu Geologicznego

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2017

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nr 470

17--47

PL

Południowo-wschodnia Polska znajduje się na obszarze kontaktu trzech dużych jednostek geologicznych: kratonu wschodnioeuropejskiego (EEC), platformy paleozoicznej i Karpat. Złożoną budowę geologiczną obszaru odzwierciedlają mapy anomalii pól potencjalnych. Analiza mapy anomalii ΔT całkowitego pola magnetycznego Ziemi i pochodnych pionowych tych anomalii w powiązaniu z danymi geologicznymi dostarcza wielu informacji o budowie i właściwościach magnetycznych skał krystalicznego kompleksu skorupy. Pośrednio ujawnia ona stopień zróżnicowania petrologicznego i tektonikę krystalicznego kompleksu skorupy obszaru kratonicznego w zestawieniu ze skorupą przyłączonych do niego bloków, będących przedpolem orogenu waryscyjskiego platformy paleozoicznej i zlokalizowanych w strefie szwu transeuropejskiego (TESZ). Na drodze analizy spektralnej anomalii magnetycznych i ich ilościowej interpretacji, uwzględniającej dane z projektu CELEBRATION 2000 oraz informacje o właściwościach magnetycznych skał udostępnionych wierceniami, skonstruowano wzdłuż profili sejsmicznych (CEL 01, CEL 05) dwuwymiarowe (2D) modele magnetyczne skorupy i przedstawiony w formie szkicu model trójwymiarowy (3D). Porównawcza analiza i interpretacja map anomalii magnetycznych i grawimetrycznych ujawniła pozycję krystalicznego kompleksu skorupy w strefie kontaktu kratonu wschodnioeuropejskiego z platformą paleozoiczną oraz jego wpływ na obraz resztkowych anomalii grawimetrycznych na obszarze kratonu

EN

South-eastern Poland is situated between the East European Craton (EEC), the Paleozoic and Mezosoic of Western Europe and the Carpathians. Complex geological structure of the area is reflected on the maps of potential fields anomalies. The analyses of the total magnetic intensity anomaly map ΔT and the vertical derivatives of these anomalies in relation to geological data provide many information concerning the structure and magnetic properties of rocks of the crystalline basement. These analyses indirectly reveal the degree of the petrologic diversification and the tectonics of the basement in comparison with the adjoining blocks of the Paleozoic and Variscan orogens and their basement as well as those located in the area of the Trans–European Suture Zone (TESZ). Two dimensional (2D) magnetic models of the basement along the seismic profiles (CEL 01, CEL 05) and corresponding three dimensional (3D) model have been constructed. This interpretation is based on spectral analysis of the magnetic anomalies and their quantitative interpretation which includes data from the CELEBRATION 2000 project, as well as information concerning the magnetic properties of rocks made available through drilling. The comparative analysis of maps showing magnetic and gravity anomalies have revealed the architecture of the crystalline basement in the area where the East European Craton (EEC) is in contact with the Paleozoic and Mezosoic of Western Europe, as well as its impact on the image of residual gravity anomalies within the area of the craton.