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    Wyświetlanie 1-5 z 5
    Tytuł:
    Vestiges of Cambro-Ordovician continental accretion in the Carpathian-Balkan orogen: First evidence of the ‘Cenerian’ event in the central Serbo-Macedonian Unit
    Autorzy:
    Spahić, Darko
    Bojić, Zoran
    Popović, Danica
    Gaudenyi, Tivadar
    Powiązania:
    https://bibliotekanauki.pl/articles/1835596.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Cenerian event
    North Gondwana
    Serbo-Macedonian Unit
    supragetic basement
    Lower Paleozoic paleosuture
    migmatites
    shear zones
    Gondwana
    dolny paleozoik
    migmatyt
    strefa ścinania
    Opis:
    In the Balkans, the Serbo-Macedonian Unit (SMU), Serbia, is thrust bounded by the composite Tethyan Vardar Zone and the Carpatho-Balkanides. The SMU actually emerges from beneath the Neoalpine Miocene-Pliocene deposits. Both provenance and geodynamic position of the SMU are poorly known and still debated. This paper reviews the data hitherto published and includes some new field data interpretations. The SMU is composed of a Neoproterozoic-Cambrian high-grade (para- and ortho-) gneiss with peraluminous magmatic arc components (560-470 Ma). The SMU is in the contact with Neoproterozoic upper Ordovician-Carboniferous low-grade metasedimentary succession of an accretionary wedge assembly represented by the Supragetic basement. The SMU basement became folded, sheared and metamorphosed around 490-450 Ma. Paleomagnetic data point to high southern latitudes and a peri-Gondwanan position of the SMU at that time, which concurs with glaciomarine evidence recorded from the upper Ordovician sediments at the base of an accretionary wedge succession. Based on the published data and field survey in the Stalać region, we correlate the SMU with the pre-Mesozoic gneiss terrane exposed in the Strona-Ceneri zone of the Alps. This terrane, identified as the Cenerian orogen of the Alaskan subduction type, developed at an active margin of Gondwana during middle Ordovician times. The SMU basement, with augen and migmatitic gneisses and arc-related peraluminous magmatic bodies, developed at this margin as part of the Cenerian belt or its equivalent. Such an orogenic edifice proved transient and in the earliest Silurian the SMU fragments drifted away being bound for Baltica (amalgamated Moesian microplate and Danubian terrane) to which they became accreted in the Carboniferous and included in the southern European branch of the Variscan orogen (Marginal Dacides/Carpatho-Balkanides). Despite consider-able Variscan and Alpine reworking, the pre-Variscan, Cenerian-type crustal assembly along with an inferred boundary between the magmatic arc and the accretionary wedge, accompanied by back-arc/forearc deposits, are still decipherable in the Western Balkan countries.
    Źródło:
    Acta Geologica Polonica; 2021, 71, 2; 219-247
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Struktury hydratacyjne i deformacyjne w skałach czapy gipsowej wysadu solnego Dębiny w rowie Kleszczowa
    Deformation and hydrational structures in cap rocks of the Dębina Salt Dome, the Kleszczów Graben, central Poland
    Autorzy:
    Krzesińska, A.
    Redlińska-Marczyńska, A.
    Wilkosz, P.
    Żelaźniewicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2074779.pdf
    Data publikacji:
    2010
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    wysad solny Dębiny
    czapa skalna
    gips
    stylolity
    strefa ścinania
    rekrystalizacja
    Dębina Salt Dome
    cap rock
    gypsum
    stylolites
    shear zones
    recrystallization
    Opis:
    The Dębina salt dome is situated in central part of the Tertiary Kleszczów Graben, central Poland. Cap rocks of the dome were characterized on the basis of analysis of core material from a well drilled in the northern part of that structure. The cap rock sequence may be subdivided into two parts. Its lower part with breciated structure represents residuum from dissolution of saline series whereas the upper comprises rocks developed by coalescence of shale cover with gypsum. Gypsum rocks of the cap form 6 lithotypes. In these lithotypes it is possible to distinguish: 1) recrystallizational structures developed during diagenesis and multiple hydration transformations, 2) structures developed in a local stress field related to displacements evoked by dissolution of the cap rocks and fluid circulation. Structures of the first type include microcrystalline gypsum with anhydrite relics and carbonate nodules, lenticular and acicular gypsum, porphyroblastic and even-grained gypsum as well as vein gypsum and first generation of stylolites. The other type of structures is represented by: gypsum showing shape fabrics and associated gypsum nodules, gypsum grains with geometry of -clasts, fibrous gypsum in pressure shadows, structures of the core-and-mantle type, subgrains developing in bigger crystals and second generation of stylolites and slickolites. Five sets of fractures were recorded. These fractures developed in the cape rocks under stress field with the vertical maximum stress axis and active shear planes. The normal faults of B, C and D sets could be formed during upward motion of the dome, its stagnation, or during gravitational collapse triggered by karst processes. Oblique striations on microfault B surfaces point to later reactivation under local normal-slip regime caused by ongoing subsidence of the cap rocks, or alternatively - a reactivation that occurred in response to external stress field which controlled evolution of the extensional Kleszczów Graben.
    Źródło:
    Przegląd Geologiczny; 2010, 58, 6; 522-530
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Strefy ścinania podatnego na obszarze złoża rud Fe-Ti-V „Udryń suwalskiego masywu anortozytowego
    Ductile shear zones from the "Udryń" Fe-Ti-V ore deposits of the Suwałki anorthosite massif
    Autorzy:
    Cymerman, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2063342.pdf
    Data publikacji:
    2006
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    mylonity
    strefy ścinania
    nasunięcia podatne
    kinematyka
    złoże rud Fe-Ti-V Udryń
    mylonites
    shear zones
    ductile thrusting
    kinematics
    "Udryń" Fe-Ti-V ore deposit
    Opis:
    Wykonano analizę strukturalną nieorientowanych rdzeni (ok. 10 000 m) z 12 otworów wiertniczych z obszaru złoża rud Fe—Ti—V „Udryń" (suwalski masyw anortozytowy; Polska północno-wschodnia). Szczególną uwagę zwrócono na rozpoznanie stref ścinania podatnego w zachowanym materiale wiertniczym, których stwierdzono co najmniej 485, a także orientacji foliacji mylonitycznej SM i lineacji ziarna mineralnego (z rozciągania) LM oraz ustaleniu asymetrycznych wskaźników kinematycznych. Wyniki tych badań umożliwiły określenie kierunku transportu tektonicznego i charakteru deformacji domen skalnych w poszczególnych otworach i na obszarze złoża „Udryń". Kąty upadu foliacji SM wynoszą ok. 50-60°. Lineacja z rozciągania LM jest w przybliżeniu równoległa do kierunku upadu foliacji SM. Te elementy strukturalne uznano za pozostałość po orogenezie gotyjskiej (ok. 1,55-1,45 mld lat), która charakteryzowała się skracaniem i zlokalizowanym rozwojem podatnych nasunięć. Problemem jest wiarygodność orientacji foliacji SM ustalona na podstawie skrzywień osi otworu. Wykorzystując dane z pomiarów skrzywienia osi otworów przyjęto, że bieg foliacji SM w skali regionalnej jest zgodny z kierunkiem NW—SE do WNW—ESE. Prawie wszystkie wskaźniki zwrotu ścinania wskazują na inwersyjny (nasunięciowy) zwrot przemieszczeń ku NE. Rozwój silnie heterogenicznych stref ścinania podatnego wpływał na rozmieszczenie i formy ciał rudnych na obszarze złoża „Udryń". Prawdopodobnie liczne wystąpienia rud ilmenitowo-magnetytowych w okolicy Udrynia znajdują się głównie w domenach frontalnych i/lub spągowych w szeregach łusek ponasuwanych ku NE. W większym stopniu lokalnie rozwinięte i młodsze były procesy tektoniczne związane z podatno-kruchym i kruchym uskokowaniem.
    Detailed structural analysis of non-oriented drill cores (ca. 10,000 m) from 12 deep boreholes from the "Udryń" Fe—Ti—V ore deposits area (the Suwałki anorthosite massif, NE Poland) has been carried out. Special attention has been paid to recognition of ductile shear zones in preserved drill cores, probably more than 485 zones, attitudes of the SM mylonitic foliation and the LM extensional (mineral) lineations, and to kinematic indicators. The results of the analysis made it possible to establish the direction of tectonic transport and deformation regimes in individual boreholes and throughout the area of the "Udryń" ore deposits. In general, the dip angle of the SM foliation is about 50-60° with approximately parallel to the dip of the LM stretching lineations. Both the structural elements are inferred to be remnants of the Gothian orogeny (ca. 1.55-1.45 Ga) with shortening and localised ductile thrusting. There are problems in the reliability of the SM foliation orientations using curving axis of individual boreholes. On the basis of the curvature axis it is proposed that the strike of SM foliation is consistent at a regional scale with NW—SE to WNW—ESE directions. Almost all shear sense indicators show reverse sense of movements with the top to the NE. The development of strongly heterogeneous ductile shear zones controlled the distribution and shapes of ore deposits in the vicinity of Udryń. It is quite probable that frequent occurrences of ilmenite-magnetite ores in the vicinity of Udryń are situated mainly in frontal and/or bottom domains of thrust sheets displaced towards the NE. More localised and younger tectonic processes were connected with ductile-brittle and brittle conditions during faulting.
    Źródło:
    Biuletyn Państwowego Instytutu Geologicznego; 2006, 421; 15--51
    0867-6143
    Pojawia się w:
    Biuletyn Państwowego Instytutu Geologicznego
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microstructures of shear zones from selected domains of the Western Tatra Mountains
    Autorzy:
    Kania, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059986.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    structures
    kinematics
    shear zones
    Western Tatra Mountains
    Opis:
    The paper is focused on the meso- and microstructural characteristics of selected shearing zones in the Western Tatra Mts. The domains of crystalline rocks studied (Długi Upłaz Ridge, Rakoń Mt., Zabraty Ridge and Zabrať Pass, Wołowiec Mt., Trzydniowiański Mt., Czubik Mt. and Jarząbczy Mt.) show evidences of heterogeneous shearing with development of shear zones. Four types of shear zones were distinguished: (1) ductile shear zones in gneisses, (2) brittle-ductile complex shear zones, (3) gneisses with clear later brittle deformation; (4) leucogranites, produced by anatexis with later brittle deformation. The development of these shear zones is characterised by occurrences of various types of fault rocks: cataclasites, S-C cataclasites and mylonites. The different shearing-related rocks and structures are interpreted as an effect of protolith diversity and strain partitioning. Shape-preferred orientation is an important structural feature of all the shearing-related rocks. Kinematic analyses revealed generally a southward sense of shearing documented by structures related to brittle conditions and northwards sense of shearing recognised in ductily sheared crystalline rocks. The time relationships between different shear zone types are discussed, leading to the conclusions that the 1st type of shear zone is pure Variscan, the 2nd type is Variscan with Alpine brittle deformation, and the 3rd and 4th types are mainly Alpine brittle deformations of Variscan syntectonic anatectic leucogranites.
    Źródło:
    Geological Quarterly; 2015, 59, 4; 679--699
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microfabric diversity and grain shape analysis of fault rocks from the selected areas of the Western Tatra Mountains
    Autorzy:
    Kania, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059963.pdf
    Data publikacji:
    2014
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    microfabrics
    grain shape analysis
    fault rocks
    shear zones
    Western Carpathians
    Western Tatra Mountains
    Opis:
    Fault rocks in brittle and brittle-ductile shear zones played a key role in the evolution of the Western Tatra Mountains crystal- line rocks (Poland-Slovakia). Microfabrics of these rocks, including grain shape analyses, were investigated in the six areas of the Western Tatra Mountains. Based on studies of thin sections, 14 types of fault rock microfabric are distinguished, ac- cording to the following criteria: (a) the presence and abundance levels of a cataclastic matrix and (b) the presence and form of a preferred orientation features. General tendencies observed in these areas indicate southwards increasing non-coaxial deformation as well as the domination of ultracataclasites or ultramylonites to phyllonites in areas with negative relief (e.g., sedlo Zabrat’ Pass, Dziurawa Przełęcz Pass). A model of shear zone evo l u tion embracl ng foll owl ng three stages is pro- posed: (1) deformation partitioning and block-controlled cataclastic flow, (2) matrix-controlled cataclastic flow, (3) selective leaching and deposition of silica, leading to the formation of softened and hardened deformation domains respectively. These microstructural observations were supported by statistical analyses of the grain shape indicators (compactness, isometry, ellipticity, solidity, convexity). Two trends of relationships between compactness and convexity were noted: the first, horizontal on the correlation diagrams, was interpreted as an effect of rapid cataclasis and then sericitization, the sec- ond, with a strongly negative correlation coefficient, was considered as an effect of long-term cataclastic flow. The different microfabric data and microstructural interpretations described in this paper are consistent with a new model of the tectonic history of the Western Tatra Mountains evolution, with an important role for a non-coaxial deformation during Alpine orogeny in brittle and brittle-ductile conditions.
    Źródło:
    Geological Quarterly; 2014, 58, 1; 3--18
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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