Wyniki wyszukiwania - BazTech

1

Unraveling the collisional history of the Western Carpathians through deep geophysical sounding

Soni Tanishka, Schiffer Chrystian, Mazur Stanisław

Geotourism / Geoturystyka

|

2023

|

nr 1-2 (72-73)

65--66

EN

The ALpine-CArpathian-PAnnonian (ALCAPA) block is one of the terranes involved in the Alpine-Tethys suture along with the North European Plate. In the Western Carpathians, this suture is supposed to be represented by the Pieniny Klippen Belt (PKB) which is a few kilometres wide and about 600 km long unit between the Outer Western Carpathians (OWC) and Central Western Carpathians (CWC) (Plašienka et al., 1997; Schmid et al., 2008). Unlike the Neotethian suture in the Western Carpathians, the PKB does not show the typical characteristics of a suture. The PKB is a sub-vertical unit with mainly shallow marine limestone and flysch deposits in a conspicuous “blockin-matrix” structure (Plašienka et al., 1997). The presence of “exotic” sediments in the PKB and the southernmost units of the OWC along with their shallow marine deposition environment led to the theory proposing the presence of a continental sliver called the Czorsztyn Ridge in the Alpine Tethys, dividing it into two oceanic/marine basins: the Magura Ocean to the north and the Vahic Ocean to the south (Plašienka, 2018). This controversial continental fragment possibly forming the basement for PKB successions, and its structural relationship with the adjoining OWC and CWC units, make it the main target of this project. The objective is to find evidence of the presence of this continental block, the Czorsztyn Ridge, which may have subducted along with the Vahic oceanic lithosphere underneath the CWC (Schmid et al., 2008). A passive seismic experiment will provide insight into the deep lithospheric structure across the PKP, testing the presence of a tectonic suture along with relaminated remnants of the Czorsztyn Ridge, and potential remnants of subducted or underthrusted lithosphere. Eighteen broadband stations have been deployed in a ~N-S transect (Fig. 1a) under the umbrella of the AdriaArray initiative, cutting across the PKB and Neotethian Meliata suture to the south. The data obtained during up to three years will complement 10 other permanent and temporary broadband stations, forming an approximate 370 km long profile and will be used to perform receiver function analysis and build structural and velocity models of the lithosphere (i.e., Schiffer, 2014; Schiffer et al., 2023) beneath the Western Carpathians. The horizontal extent of the imaging is shown in Figure 1b.

2

Skorupa oceaniczna i ofiolity w Sudetach Środkowych w świetle rozważań tektonicznych

Cymerman Z.

Przegląd Geologiczny

|

2017

|

Vol. 65, nr 12

1540--1547

EN

Znosko (1981a, b) first stated the important fact that the Sowie Góry "nappe” was lying on the rocks of the Middle Sudetic Ophiolite Complex. In the light of current geophysical and tectonic data, it still remains up-to-date. Both those articles have initiated a new look at the Paleozoic tectonic evolution of the Sudetes and its surroundings. This article presents an analysis ofpotential boundaries oflithostratigraphic terranes in the Sudetes and the Fore-Sudetic Block, confirmed by the waveforms of gravity horizontal gradients. Gravimetric modelling along the selected profile 3 makes it possible to present the subsurface geological structure. Metamorphic rocks of the Sowie Góry complex can probably reach a depth of almost 5 km on the Fore-Sudetic Block. Below them are mafic and ultramafic rocks, reaching a depth of up to 12 km, which belong to the Middle-Sudetic Ophiolite Complex. The kinematic data from the Sowie Góry metamorphic complex indicate displacement with the top-to-SW and to-S, as in the Middle-Sudetic Ophiolite Complex. Controversy over the origin and the geotectonic environment of the Early Ordovician protolith of the Sowie Góry gneisses, which are probably a magma product of arc-type magmatism formed above a subduction zone of the Tornquist Ocean. The Sowie Góry terrane can be considered as a relic of the Early Ordovician Paleozoic magma arc (the so-called peri-Baltic arc). The Sowie Góry terrane was moved towards the SW and S on obducted dismembered fragments of ophiolite sequences after closing the Rheic Ocean during the Eo-Variscan orogenesis.

3

O nowych rozwiązaniach tektonicznych w „Atlasie geologicznym Polski”

Aleksandrowski P., Mazur S.

Przegląd Geologiczny

|

2017

|

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.

4

Jeszcze raz o terranach w Polsce i ich wędrówce

Nawrocki J.

Przegląd Geologiczny

|

2015

|

Vol. 63, nr 11

1272--1283

EN

Results of interdisciplinary studies conducted until now lead to a univocal conclusion that Poland should be regarded as a collage of terranes of different ages and provenances of the basement, and different amalgamation and accretion scenarios. Geophysical and tectonic-structural investigations have allowed defining, with different accuracies, the boundaries between particular terranes. Terranes located in the area of Paleozoic platform were subjected to two or three phases of mobility. The first phase of transcontinental scale was manifested by large-scale tectonic transport during rebuilding of global paleogeography. The second mobility phase of regional scaleaffected the Teisseyre-Tornquist terrane assemblage and was linked with the Laurentia and Avalonia collision. This process put in motion the escape tectonics in the earliest Devonian. As its result, some of terranes were reshuffled during their tectonic transportation in the SE direction. The third, Carboniferous phase of mobility of only local scale was related mainly to the dextral strike-slip tectonic activity. Unfortunately, in the case of several tectonostratigraphic units, an answer to the questions concerning their initial location and way of migration is still impossible. It is valid also in the case of the Teisseyre-Tornquist terrane assemblage, now located to the SE of the Moravia and Grójec fault zones. This reticence in geological diagnosis occurs in spite of generally good access to the rocks of the Brunovistulia and Małopolska terranes that could contain substantial information about the earliest stages of evolution of these units. In order to eliminate numerous gaps in our knowledge about the Polish terranes a new interdisciplinary scientific program should be developed.

5

Ewolucja strukturalna utworów dolnopaleozoicznych w strefie granicznej bloków górnośląskiego i małopolskiego

Żaba J.

Prace Państwowego Instytutu Geologicznego

|

1999

|

T. 166

1--162

PL

Na podstawie szczegółowej analizy mezostrukturalnej i mikroskopowej próbek wiertniczych, pochodzących z utworów paleozoicznych strefy krawędziowej bloków górnośląskiego i małopolskiego, wyróżniono kilkanaście etapów ewolucji strukturalnej tego obszaru. Wiążą się one ściśle z wielofazową aktywnością strefy uskokowej Kraków-Lubliniec, będącej prawdopodobnie segmentem transkontynentalnej linii tektonicznej Hamburg-Kraków. Strefa ta, o założeniach proterozoicznych, stanowi bezpośrednią granicę między blokami (terranami) górnośląskim i małopolskim. Budowa strukturalna, litologia oraz wiek serii dolnopaleozoicznych tworzących brzeżne części tych bloków znacznie różnią się od siebie. Wspólne dla obu bloków kompleksy litostratygraficzno-strukturalne pojawiają się dopiero od dewonu dolnego. W utworach paleozoicznych brzeżnej części bloku górnośląskiego zaznaczyły się trzy fazy deformacji tektonicznych, prowadzące do tworzenia się makrostruktur fałdowych, natomiast w krawędziowej strefie bloku małopolskiego stwierdzono przejawy czterech takich deformacji (z uwzględnieniem kompleksu ?wendyjsko-dolnokambryjskiego). W strefie kontaktowej bloków górnośląskiego i małopolskiego dominującą rolę odegrały ruchy o charakterze przesuwczym, których szczególnie duża aktywność zaznaczała się w dwu okresach: pod koniec syluru (lewoskrętna transpresja) oraz w karbonie górnym (prawoskrętna transpresja i transtensja). Z tym drugim okresem łączy się powstanie intruzji granitoidów. Występują one tylko w brzeżnej części bloku małopolskiego. Na obszarze tym koncentruje się też większość zjawisk metamorficznych; przeobrażenia o charakterze regionalnym objęły tylko utwory kompleksu wendyjsko-dolnokambryjskiego, natomiast zmiany kontaktowe ściśle wiążą się z górnokarbońskim magmatyzmem, zaznaczając się - poza metasedymentami powyższego kompleksu - również w osadach ordowiku, syluru oraz dewonu.