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    Wyświetlanie 1-12 z 12
    Tytuł:
    Palaeozoic orogeneses in the Sudetes: a geodynamic model
    Autorzy:
    Cymerman, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059384.pdf
    Data publikacji:
    2000
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Sudetes
    Variscan
    Palaeozoic
    transpression
    extension
    orogeny
    Opis:
    The Palaeozoic geodynamic evolution of the Sudetes resulted from two successive orogenic events: (1) Ordovician-Silurian geotectonic processes (pre-Variscan stages), and (2) the Variscan orogeny. Early Palaeozoic rifting of Cadomian crustal segments and opening of the Ligerian (Galicia-Massif Central) and/or Saxothuringian Ocean occurred in Ordovician-Silurian times on the northern (peri-Gondwana) periphery of the Bohemian Massif. At the same time, the Góry Sowie terrane with a magmatic arc affinity quite probably developed on the SW margin of Baltica due to subduction of the Tornquist Ocean. Two major structural events characterised the Variscan evolution of the Sudetes: (1) regional-scale ductile thrusting of Late Devonian-Early Carboniferous age, and (2) Early Carboniferous-Early Permian regional extension. Ductile thrusting is characterised by: (I) a general NNE-directed, dextral transpressional stacking of ductile nappes due to oblique collision of the Moldanubian and Moravian microplates in the Eastern Sudetes, and (II) SW- to NW-directed, sinistral transpressional stacking of ductile nappes due to westward lateral extrusion of continental crust in the Central and Western Sudetes, itself a result of oblique indentation of the Central Sudetic oceanic lithosphere. The first Variscan deformation in the Sudetes might reflect a purely convergent setting that evolved into a transpressive setting during oblique convergence. Special attention is given to the geometry and kinematics of intraplate tectonic escape and a model of indentation processes in the Sudetes. The presented new geotectonic model for the Variscan evolution of the Sudetes is consistent with lateral escape of the Saxothuringian terrane as an important way of accommodating Variscan strain in the NE part of the Bohemian Massif. This model explains the lateral expulsion (escape) process as due to the indentation of the Central Sudetic terrane along with the Góry Sowie terrane and by the oblique subduction of the Ligerian/Saxothuringian Ocean(s) (now tectonically dismembered ophiolitic rocks of the Central Sudetic terrane).
    Źródło:
    Geological Quarterly; 2000, 44, 1; 59-80
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An insight into a gneiss core of the Orlica–Śnieżnik Dome, NE Bohemian Massif : new structural and U-Pb zircon data
    Autorzy:
    Redlińska-Marczyńska, A.
    Żelaźniewicz, A.
    Fanning, C. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059909.pdf
    Data publikacji:
    2016
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Cambrian
    migmatites
    Variscan orogeny
    SHRIMP
    Sudetes
    Opis:
    The Orlica–Śnieżnik Dome in the Sudetes, the NE Bohemian Massif, embraces two formations of felsic gneisses of controversial origin and evolution. Our study shows that despite similar geochemical signatures, they carry systematic minor differences in mineral, isotope, zircon and geothermobarometric characteristics. Four variants of the Gierałtów gneisses include migmatites and have a longer structural history than the Śnieżnik augen orthogneisses. U-Pb SHRIMP analyses yielded U-Pb ages of ~500 Ma for cores and ~498 Ma for wide outer parts of zircon grains in the twice-folded Gierałtów gneisses, and an age of ~500 Ma for a discordant neosome vein. Neoproterozoic metasediments were among precursors of the lithologically diversified Gierałtów Gneiss Formation. First deformation, metamorphism, and migmatisation of these rocks occurred at 515–475 Ma and overlapped with the development and emplacement of a porphyritic S-type granite precursor to the Śnieżnik Gneiss Formation. The metagranite (= Śnieżnik augen orthogneiss) embraced migmatitic xenoliths. Zircon grains from such xenoliths revealed distorted and replaced cores which yielded U-Pb ages that dispersed around 507–487 Ma, whilst wide darker poorly zoned outgrowths yielded ages from ~343 Ma to ~325 Ma (mean ~340 Ma). These outgrowths were interpreted as a record of Carboniferous metamorphism assisted by rich Zr- and U-carrying fluids. The Variscan metamorphic overprint was heterogeneous, and variously affected rocks of the two gneiss formations.
    Źródło:
    Geological Quarterly; 2016, 60, 3; 714--736
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ambiguous geological position of Carboniferous rhyodacites in the Intra-Sudetic Basin (SW Poland) clarified by SHRIMP zircon ages
    Autorzy:
    Kryza, R.
    Awdankiewicz, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2058977.pdf
    Data publikacji:
    2012
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Sudetes
    Variscan orogeny
    Carboniferous
    SHRIMP zircon dating
    volcanism
    subvolcanic intrusions
    Opis:
    Rhyodacite sheets (the Sady Górne Rhyodacites) in the lowermost part of the Permo-Carboniferous Intra-Sudetic Basin molasse fill have been mapped as intrusives but, later on, based on ambiguous field and petrographic evidence, reinterpreted as lower Carboniferous lavas and tuffs; if so, they would mark the earliest episode of late-orogenic volcanism in the Intra-Sudetic Basin and in the whole Sudetes region in SW Poland. However, re-examination of field relationships and new observations are consistent with an intrusive emplacement of the rhyodacites as conformable to semiconformable, simple to composite sheets. SHRIMP zircon study indicates that the rhyodacites contain rare inherited zircons of ca. 560 Ma, and ca. 470 Ma (or slightly older), and a main population of zircons with an average concordia age of 306.1 š2.8 Ma. This latter age documents the emplacement of the rhyodacites during a mid/late late Carboniferous (Westphalian) stage of volcanism in the Intra-Sudetic Basin in the Central European Variscides. This post-orogenic volcanism was possibly initiated several million years later than previously assumed, and could have comprised a few pulses over a relatively prolonged time span of millions of years.
    Źródło:
    Geological Quarterly; 2012, 56, 1; 55-66
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Collision Between Indochina and South China Blocks in Northwestern Vietnam and its Controversy
    Autorzy:
    Hung, Khuong The
    Golonka, Jan
    Du, Nguyen Khac
    Powiązania:
    https://bibliotekanauki.pl/articles/27323226.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Przeróbki Kopalin
    Tematy:
    Indochina block
    South China block
    collision
    Indosinian orogeny
    Indochiny
    Chiny
    kolizje
    Opis:
    The Indosinian orogeny, which was regarded as the collision event between the South China and Indochina blocks that occurred in Southeast Asia, including Vietnam, resulting in the formation of the Indosinian mountain range. However, the question of how many times collision between these blocks occurred in the past and during which period remains unanswered. Furthermore, the closure of the ancient ocean and the evidence of its remnants between the South China and Indochina Blocks are still the subjects of serious debate. The underlying origin of the Indosinian thermo-tectonism is uncertain. The entire region was affected by the thermal-tectonic processes in the west, caused by the collision of the Sibumasu plate and Indochina block. The absence of evidence supporting the Indosinian as a significant mountain-building event is highlighted through an examination of regional paleogeography, as well as palaeontological and thermochronological data. There is no conclusive evidence to suggest that the Indochina and South China blocks collided during the Triassic times. A plate tectonic scenario that describes the Indosinian orogeny as a reactivation event triggered by the accretion of the Sibumasu block to Indochina is favored.
    Źródło:
    Inżynieria Mineralna; 2023, 2; 103--112
    1640-4920
    Pojawia się w:
    Inżynieria Mineralna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Podiform chromitites from the Variscan ophiolite serpentinites of Lower Silesia (SW Poland) : petrologic and tectonic setting implications
    Autorzy:
    Wojtulek, P. M.
    Puziewicz, J.
    Ntaflos, T.
    Bukała, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060165.pdf
    Data publikacji:
    2016
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    ophiolite
    chromitite
    platinum group elements
    PGE
    supra-subduction setting
    Variscan orogeny
    Opis:
    The Gogołów-Jordanów Serpentinite Massif (GJSM) and the Braszowice-Brzeźnica Massif (BBM) are the largest serpentinite outcrops in the Fore-Sudetic Block (NE part of the Bohemian Massif, Central Europe). The GJSM is a peridotitic member of the Variscan Ślęża Ophiolite (SW Poland). Podiform bodies (veins and pockets) of chromitite are found on the Czernica Hill (GJSM) and on the Grochowiec Hill (BBM) within strongly serpentinized harzburgites which occur several hundred metres below Paleo-Moho. Chromitites consist of rounded chromite grains up to 3 cm across, and of chlorite filling the interstices. The veins are embedded in serpentine-olivine-chlorite aggregates. Relics of Mg-rich olivine (Fo95-96) occur in massive chromitite in the BBM. The bulk-rock total PGEs content is very low (42-166 ppm) and the PGE pattern is negatively sloped towards Pt and Pd and depleted relative to chondrite. The primary chromite I is aluminous (Cr# 0.50-0.52, Mg# 0.60-0.70). The highly aluminous and magnesian (Cr# 0.38, Mg# 0.80) chromite Ia occurs locally in the BBM. The secondary chromite II is enriched in Cr and impoverished in Al (Cr# 0.57-0.69), it replaces chromite I. Both chromite I and II contain small amounts of Ti (<0.14 wt% TiO2). Silicate inclusions in chromite are scarce. The composition and mode of occurrence of both the GJSM and the BBM chromitites are similar, thus they were formed probably under the same conditions. Textures of the chromitites suggest their magmatic origin. Their current geological position indicates their emplacement and crystallization in the uppermost mantle harzburgites occurring below the Moho Transition Zone (MTZ). The chromitites and hosting harzburgites were subjected to the greenschist-facies metamorphic overprint. The moderate Cr# and low PGEs contents suggest that the chromitites originated in the arc setting, thus their host ophiolite is of supra-subduction type.
    Źródło:
    Geological Quarterly; 2016, 60, 1; 56--66
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pre-Variscan palaeogeographical structures in the Cantabrian Zone, Spain: some critical considerations regarding their origin, location and significance
    Autorzy:
    Van Loevezijn, Gerard B.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/24201074.pdf
    Data publikacji:
    2023
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    Devonian
    palaeogeography
    Variscan orogeny
    Alpine deformations
    dewon
    paleogeografia
    orogeneza waryscyjska
    deformacje alpejskie
    Opis:
    An update of the main Devonian pre-Variscan palaeogeographical features of the southern Cantabrian Zone is presented. The approximal locations of these features are recorded in sections studied, with thin, incomplete developments for the highs and thick successions for the troughs. Generally, pre-Variscan palaeogeographical features were affected by Variscan and Alpine orogenic deformations, but with a different impact. Oroclinal bending, tectonic shortening by thrusts, movements along strike-slip faults and bending by folds all affected the Devonian palaeogeographical features, and only an approximation of their location and shape can be given. Nevertheless, the palaeogeography recorded in pre-Variscan sedimentary successions and their relative positions, provide specific, clear and objective evidence of the pre-Variscan elements.
    Źródło:
    Geologos; 2023, 29, 2; 77--97
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal history of Lower Palaeozoic rocks from the East European Platform margin of Poland based on K-Ar age dating and illite-smectite palaeothermometry - 481 – 509
    Autorzy:
    Kowalska, Sylwia
    Wójtowicz, Artur
    Hałas, Stanisław
    Wemmer, Klaus
    Mikołajewski, Zbigniew
    Buniak, Arkadiusz
    Powiązania:
    https://bibliotekanauki.pl/articles/191840.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    shale gas
    K-Ar dating
    thermal history
    Variscan orogeny
    Palaeozoic
    East European Platform
    interlaboratory comparison
    Opis:
    Large-scale shale gas prospecting in the Polish part of the East European Platform did not discover large reserves of this resources. The article presents new research indicating that one of the reasons for the lack of shale gas relates to the thermal history of the Lower Palaeozoic rocks. Illite-smectite palaeothermometry was used to reconstruct the history of the platform and determine the maximum temperatures to which these rocks were subjected. The age of illitisation was also constrained using the K-Ar method. This method allowed precise dating of the maximum age of thermal transformations due to the deposition of numerous pyroclastic horizons (K-bentonite) throughout the entire geological profile from the Cambrian to the Silurian. Isotopic dating was made on over 53 samples of Lower Palaeozoic bentonites and low-grade metamorphic clays. These results were supplemented by analysis of the degree of thermal (smectite to illite) transformation in the profiles of 37 deep boreholes. 11 zones could be distinguished with different tectonic histories within the Polish part of the East European Platform edge. Maximum heating occurred in this region at about 320–340 Ma, corresponding to the Early Carboniferous or the turn of the Early and Late Carboniferous, phase A of the Variscan orogeny, known as the Sudetian phase. In the southern part of study area, the maximum of thermodiagenesis is slightly younger – 270–290 Ma, which responds to the Early Permian, the Asturian phase, the last phase of the Variscan orogeny. This means that the generation of hydrocarbons occurred before significant Mesozoic exhumation of the Polish part of the East European Platform, which led to the escape of a considerable amount of the gas generated. The study also presents the results of an interlaboratory comparison of illite age dating using the K-Ar and Ar-Ar methods. The comparison was conducted to find out what realistic error should be considered when interpreting geological K-Ar dating results.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2019, 89, 4; 481-509
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Skorupa oceaniczna i ofiolity w Sudetach Środkowych w świetle rozważań tektonicznych
    Oceanic crust and ophiolites in the Central Sudetes in the light of tectonic considerations
    Autorzy:
    Cymerman, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075680.pdf
    Data publikacji:
    2017
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    ofiolity
    terrany
    Góry Sowie
    kompleks metamorficzny
    orogeneza
    geofizyka
    Sudety
    ophiolites
    terranes
    metamorphic complex
    orogeny
    geophysics
    Sudetes
    Opis:
    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.
    Źródło:
    Przegląd Geologiczny; 2017, 65, 12; 1540--1547
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Early Devonian sinistral shearing recorded by retrograde monazite-(Ce) in Oscar II Land, Svalbard
    Autorzy:
    Ziemniak, Grzegorz
    Manecki, Maciej
    Jeanneret, Pauline
    Walczak, Katarzyna
    Kośmińska, Karolina
    Powiązania:
    https://bibliotekanauki.pl/articles/2202387.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Mineralogiczne
    Tematy:
    Retrograde monazite-(Ce)
    Svalbard’s Southwestern Basement Province
    U-Th-total Pb geochronology
    Müllerneset Formation
    Caledonian orogeny
    Opis:
    The Southwestern Basement Province of Svalbard extends northward from Sørkapp Land in the south to Oscar II Land. In the north, the Müllerneset Formation characterized by polymetamorphosed Proterozoic sedimentary rocks crops out. In this study we used an integrated tectonic and petrochronological approach to gain an insight into the structural and metamorphic evolution of the unit and surrounding basement. The Müllerneset Formation consists of two separate tectonic blocks. NNW-SSE trending retrograde foliation is associated with mineral and stretching lineation and kinematic indicators consistent with left-lateral to oblique sinistral shearing in the western block. The eastern block is characterized by the opposite sense of shear that was overturned during the Eurekan event as evidenced by unconformably overlaying Carboniferous sedimentary rocks. Conventional geothermobarometry yields the prograde peak pressure metamorphic conditions of 6.6 - 7.1 kbar at 480 - 520°C followed by peak temperature at 5.1 - 5.9 kbar and 530 - 560°C. Subsequent retrograde greenschist facies overprint is related to left-lateral NNW-SSE trending shearing. Tiny monazite occurs within foliation or overgrows allanite-(Ce), thus is interpreted as growth along a retrograde path. Th-U-total Pb dating of monazite-(Ce) provided an early Caledonian age (ca. 450 Ma) and younger population of ca. 410 ± 8 Ma. This age is consistent with previously reported 40Ar/39Ar cooling ages (410 ± 2 Ma) of muscovite supporting a retrograde growth of monazite. Petrochronological evidence combined with structural observations suggests that the Müllerneset Formation has been tectonically exhumed in the Early Devonian due to the NNW-SSE trending left-lateral shearing. Coeval folding and thrusting in the remaining basement of Oscar II Land to the east indicate a transpressional regime of the deformation in the Early Devonian. Similarly oriented contemporaneous tectonic zones within the Southwestern Basement Province of Svalbard may account for the same set of shear zones dispersing the Ordovician subduction complexes along western Spitsbergen.
    Źródło:
    Mineralogia; 2022, 53, 1; 82--108
    1899-8291
    1899-8526
    Pojawia się w:
    Mineralogia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kopuła orlicko-śnieżnicka w świetle rozważań tektonicznych
    The Orlica-Śnieżnik Dome in the light of tectonic considerations
    Autorzy:
    Cymerman, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075463.pdf
    Data publikacji:
    2016
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    geotektonika
    konstrukcje
    kinematyka
    ścinanie sferoidalne
    kopuła orlicko-śnieżnicka
    orogeneza waryscyjska
    geotectonic
    structures
    kinematics
    ductile shearing
    Orlica-Śnieżnik Dome
    Variscan orogeny
    Opis:
    The paper presents tectonic considerations on the geology of the Orlica-Śnieżnik Dome (OSD), based on the published geotectonic, structural and kinematic data and reports on the OSD geotectonic setting, relating to the evolution of the Variscan collisional belt. Further progress has been done in the recognition of the structure and evolution of the OSD, and for many decades the dominant structural geology has been replaced with multithreading researches. However, the current tectonic interpretations are matched against pre-established schemas of structural evolution of the OSD. The OSD is most likely a fragment of the Moldanubian Terrane with the Variscan collisional sutures. The dextral transpression in a general shear regime and with the participation of strain partitioning has formed a thrust sheet package with the dominant tectonic transport top-to-the NNE, N and NW, with the exception of the NE part of the OSD. The development of regional-scale ductile shear zones in the OSD took place during the progressive tectono-metamorphic evolution from about 360 to 335 Ma. These processes resulted from the highly oblique collision of the Moldanubian Terrane (with the OSD) with the Brunovistulicum on the east and the Tepla-Barrandian Terrane on the W, and with a frontal collision with the Central Sudetic Terrane on the N.
    Źródło:
    Przegląd Geologiczny; 2016, 64, 10; 814--830
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ewolucja tektonometamorficzna marmurów i otaczających łupków łyszczykowych formacji strońskiej (Sudety)
    Tectonometamorphic evolution of marbles and adjacent mica schists of the Stronie Formation (Sudetes)
    Autorzy:
    Jastrzębski, Mirosław
    Powiązania:
    https://bibliotekanauki.pl/articles/94229.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    ewolucja tektonometamorficzna
    formacja strońska
    kopuła orlicko-śnieżnicka
    Masyw Czeski
    orogeneza waryscyjska
    tectonometamorphic evolution
    Stronie Formation
    Orlica-Śnieżnik Dome
    Bohemian Massif
    Variscan orogeny
    Opis:
    Połączone badania strukturalne, petrograficzne oraz geochronologiczne nad relacjami P-T-d (ciśnienie-temperatura-deformacja) w marmurach i otaczających łupkach łyszczykowych kopuły orlicko-śnieżnickiej (KOŚ) przyczyniły się do rekonstrukcji ewolucji tektonicznej wschodniej krawędzi Sudetów Zachodnich. Wyniki przeprowadzonych badań wykazały, iż na wskutek skrócenia tektonicznego w kierunku E-W (etap D1), związanego z waryscyjską kolizją domen kontynentalnych Sudetów Zachodnich oraz Brunowistulii, doszło do powstania stromej foliacji SI, pogrubienia skorupy i pogrążenia skał formacji strońskiej na głębokości odpowiadające ciśnieniom 0.9-1.0 GPa. Początkowe fazy wynoszenia skał, stowarzyszone ze pionowym skracaniem tektonicznym (etap D2), były powiązane z progresją metamorfizmu regionalnego od warunków facji zieleńcowej do facji amfibolitowej. Pod koniec etapu D2, podczas ustalenia się piku temperaturowego metamorfizmu, ukształtowała się strefowość metamorfizmu zapisana w skałach formacji strońskiej. Etap D2 doprowadził do wykształcenia leżących wąskopromiennych fałdów F2, deformujących foliację S1, oraz do spłaszczania więźby wewnętrznej zakonserwowanej w granatach. Progresywna deformacja etapu D2 ostatecznie doprowadziła do ukształtowania się subhoryzontalnej foliacji osiowej S2, którą w łupkach łyszczykowych stanowi powszechnie obserwowane złupkowanie. Podczas dalszego wynoszenia skał doszło do lokalnej reaktywacji foliacjj S2 w reżimie góra-ku-N, odpowiedzialnej za wytworzenie się stref ścinania. Późniejsze skracanie tektoniczne w kierunku NE-SW (etap D4) mogło wiązać się z regionalnym fałdowaniem i reorientacją powierzchni strukturalnych S2 || S3 oraz powierzchni izoterm/izograd metamorficznych, zaś na wskutek skracania tektonicznego w kierunku NW-SE (etap D5), doszło do nachylenia tych powierzchni w kierunku W/NW. Oba końcowe etapy mogły być odpowiedzialne za obserwowany kształt izograd metamorficznych, a także zmniejszanie się stopnia metamorfizmu w kierunku W/NW.
    Integrated structural, petrographic and geochronological studies on P-T-d record in marbles and adjacent mica schists of the Orlica-Śnieżnik Dome (OSD) contribute to a model of the tectonic development of the eastern borderland of the West Sudetes. The results of these studies show that marbles of the OSD experienced E-W directed subhorizontal shortening (D1 stage), which resulted from the Variscan collision between the West Sudetes domain and the Brunovistulian terrane. These processes led to crustal thickening, development of a steep metamorphic fabric, and the burial of the Stronie Formation to depths corresponding to 0.9-1.0 GPa. Subsequent vertical shortening (D2 stage) was related to the onset of uplift and progression of metamorphism from greenschist to amphibolite facies conditions. Under peak conditions in the temperature, metamorphic zonation was established in the Stronie Formation. The D2 shortening led to folding of the 51 planes to form recumbent tight folds (F2), and to flattening of the inclusion trails in syn-D2 garnet porphyroblasts. Ongoing D2 deformation led to the development of subhorizontally disposed S2 axial-plane foliation. In mica schists, it is preserved as a penetrative schistosity. During progressive uplift, S2 planes were reactivated as a result of subsequent top-to-N directed transport (D3 stage). The S2 || S3 planes and S2-related metamorphic isograds were regionally folded during the D4 tectonic stage, which was characterised by NE-SW directed tectonic shortening. During stage D5, due to NW-SE directed tectonic shortening, the structural and metamorphic sur- faces became inclined toward west (or north-west). The D4 and DS stages were presumably together responsi- ble for the observed metamorphic isograds and their overall tilting toward W (or NW).
    Źródło:
    Geologos; 2008, 14, 1; 51-71
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Proterozoiczne podłoże krystaliczne polskiej części Bałtyku w świetle badań strukturalnych
    Astructural study of the Precambrian crystalline basement in the Polish sector of the Baltic Sea
    Autorzy:
    Cymerman, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075274.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    skały krystaliczne
    struktury tektoniczne
    odwierty
    Danopolonian orogenezy
    kraton wschodnioeuropejski
    południowy Bałtyk
    crystalline rocks
    tectonic structures
    boreholes
    Danopolonian orogeny
    East European Craton
    southern Baltic Sea
    Opis:
    This paper presents structural data and regional correlations based on drill cores from 8 boreholes (B2-1/80, B3-1/81, B4-1/81, B6-1/82, B6-2/85, B7-1/91, B16-1/85 and B21-1/95) penetrating Precambrian crystalline rocks in the Polish part of the Baltic Sea. The crystalline rocks from the ftom these boreholes were compared to cores from several wells in Eastern Pomerania, and the Kashubian and Warmia regions and above all with the Mesoproterozoic granitoids and metamorphic rocks of Bornholm and Southern Sweden. The pre-existing basement map of the Southern Baltic, showing Palaeoproterozoic or even Archaean granitoid massifs and narrow north-south fold belts is questioned. Instead, in the present interpretation, the studied area of the Polish part of the Southern Baltic Sea is underlain by a fragment of the Mesoproterozoic (ca. 1.47–1.43 Ga) Danopolonian („Hallandian”) orogeny, comprising mainly regional-scale ductile shear zones, which, striking probably in W–E to WNW–ESE directions, are characterized by the predominance of a thrust to transpressional strain regime with tectonic transport top-to-the S or SSW. The structural kinematic and lithological interpretations of these shear zones are based on comparison with the other parts of the East European Craton that are exposed in Bornholm and the Blekinge and Skne regions in Southern Sweden.
    Źródło:
    Przegląd Geologiczny; 2015, 63, 4; 228--238
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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