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    Wyświetlanie 1-7 z 7
    Tytuł:
    Silesian Ridge in the light of petrological analyses and LA-ICP MS U-Pb analyses of the cohesive debrites from the Istebna Formation (Silesian Nappe, Outer Western Carpathians, Poland)
    Autorzy:
    Szczuka, Monika
    Gawęda, Aleksandra
    Waśkowska, Anna
    Golonka, Jan
    Szopa, Krzysztof
    Chew, David
    Drakou, Foteini
    Powiązania:
    https://bibliotekanauki.pl/articles/2187194.pdf
    Data publikacji:
    2022
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Outer Carpathians
    Silesian Ridge
    exotic clasts
    U-Pb dating
    zircon
    rutile
    Opis:
    Exotic clasts present in flysch deposits of the Western Outer Carpathians enable investigation and reconstruction of the eroded crystalline basement of the Silesian Ridge. The flysch rocks of the Istebna Formation (Jasnowice Member: Paleocene) in the Silesian Nappe contain magmatic and metamorphic clasts derived from the Silesian Ridge basement. The crystalline rock fragments acquired from cohesive debrites were analyzed petrographically and geochemically, and zircon and rutile crystals were subject to LA-ICP-MS U-Pb dating. Granitoid clasts yielded Meso-Variscan U-Pb zircon ages (325.7 and 330.6 Ma), with older (Neoproterozoic to Paleoproterozoic) inherited cores and eNd330 = –12.0 (TDM age of 1.98 Ga). The orthogneiss clast yielded a protolith age of 1635 Ma and fingerprint of thermal reworking at ~288 Ma. Zircon crystals from the detrital clasts yielded similar U-Pb zircon ages to the granitoid clasts (311.5 to 391 and 331 Ma). The rutile crystals from sandstone yielded concordia age of 344.7 Ma. Zircon crystals from paragneiss, interpreted as a granitoid envelope, yielded 238U/206Pb ages between 557 and 686 Ma and include an inherited core of age ~1207.4 ±33.8 Ma. Age data from exotic clasts and the detrital zircon and rutile fraction suggest the core part of the Silesian Ridge was a Neoproterozoic to Mesoproterozoic envelope intruded by Meso-Variscan granitoid plutons.
    Źródło:
    Geological Quarterly; 2022, 66, 2; art. no. 20
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A U/Pb age for the Mygatt-Moore Quarry, Upper Jurassic Morrison Formation, Mesa County, Colorado
    Autorzy:
    Trujillo, K.
    Foster, J.
    Hunt-Foster, R.
    Chamberlain, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/2077340.pdf
    Data publikacji:
    2014
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Morrison Formation
    U-Pb dating
    CA-TIMS
    dinosaurs
    North American Jurassic
    Formacja Morrisona
    dinozaury
    Opis:
    Mygatt-Moore Quarry in the Brushy Basin Member of the Upper Jurassic Morrison Formation is one of the more important large dinosaur quarries in the formation, yielding fossils of sauropod dinosaurs including Apatosaurus, Camarasaurus, and an indeterminate diplodocine (cf. Diplodocus or Barosaurus), the theropod dinosaurs Allosaurus and Ceratosaurus, and the ornithischians Othnielosaurus and Mymoorapelta. Fossil wood and carbonized plants are known from the deposit, and carbonized dinosaur skin has also been discovered. We report here on a new U/Pb radiometric age for the Mygatt-Moore Quarry, from a smectitic mudstone collected at the quarry horizon. We isolated zircons using an ultrasonic separation technique and standard heavy liquid and magnetic methods, analyzed single zircons using a chemical abrasion method (CA-TIMS). The age determined for this dinosaur quarry, 152.18 ±0.29 Ma, places the quarry at the boundary between the Kimmeridgian and Tithonian stages of the Late Jurassic Period. This age can now be used to place the quarry into stratigraphic position with respect to other dated horizons in the Morrison Formation and other rock units worldwide. We will also use this age along with other ages to create a radiometrically based stratigraphic framework for the Morrison Formation.
    Źródło:
    Volumina Jurassica; 2014, 12, 2; 107--114
    1896-7876
    1731-3708
    Pojawia się w:
    Volumina Jurassica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Isotope age constraint for the Blue Dyke and Jardine Peak subvertical intrusions of King George Island, West Antarctica
    Autorzy:
    Pańczyk, Magdalena
    Nawrocki, Jerzy
    Williams, Ian S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2051639.pdf
    Data publikacji:
    2009
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Antarctica
    King George Island
    Late Oligocene
    U-Pb SHRIMP dating
    Źródło:
    Polish Polar Research; 2009, 30, 4; 379-391
    0138-0338
    2081-8262
    Pojawia się w:
    Polish Polar Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monazite Th-U-total Pb geochronology and P-T thermodynamic modelling in a revision of the HP-HT metamorphic record in granulites from Stary Gierałtów (NE Orlica-Śnieżnik Dome, SW Poland)
    Autorzy:
    Budzyń, B.
    Jastrzębski, M.
    Kozub-Budzyń, G. A.
    Konečný, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060006.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    monazite
    Th-U-total Pb dating
    thermodynamic modelling
    granulite
    Orlica-Śnieżnik Dome
    Bohemian Massif
    Opis:
    Thermodynamic modelling and monazite Th-U-total Pb dating via electron microprobe were used to improve the pressure, temperature and timing constraints of the HP-HT metamorphic record in granulites from Stary Gierałtów (NE Orlica-Śnieżnik Dome (OSD), SW Poland). The thermodynamic calculations constrained the P-T conditions to 20-22 kbar and ca. 920ºC in the felsic to intermediate granulites and 20-22 kbar and ca. 970ºC in the mafic granulite. These conditions are considered to closely represent the peak temperatures experienced by these rocks. In the intermediate granulite, the matrix monazite and monazite inclusions in garnet and allanite yielded an age of 349±2.5 Ma. An HP-HT metamorphic event with temperature conditions exceeding 900ºC, which are greater than the closure temperatures of most geochronometers, must have disturbed and completely reset the isotopic systems, including the Th-U-Pb system in the monazite. Consequently, this resetting prevented us from constraining the age of potential earlier metamorphic events or the igneous protolith. The 349±2.5 Ma age reflects the timing of the late-stage HP-HT event and cooling below 900ºC related to the initial exhumation of the granulites. A comparison of the new P-T-t constraints with previous data from the NE Orlica-Śnieżnik Dome indicates that the activation of the channels that exhumed the HP rocks to mid-crustal depths most likely initiated at ca. 350 Ma, and all the metamorphic rocks in the OSD likely shared a common Variscan evolution after ca. 340 Ma.
    Źródło:
    Geological Quarterly; 2015, 59, 4; 700--717
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Th-U-total Pb timing constraints on the emplacement of the granitoid pluton of Stolpen, Germany
    Autorzy:
    Lisowiec, K.
    Budzyń, B.
    Słaby, E.
    Schulz, B.
    Renno, A. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/950363.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Th-U-Pb chemical dating
    Lusatian Granodiorite Complex
    Stolpen Granite
    Variscan granitoids
    Łużyce
    granodioryt
    kompleks
    granit
    waryscyjskie granitoidy
    Opis:
    Monazite from the Stolpen monzogranite (SE Germany) was studied to constrain the Th-U-total Pb age of pluton formation. Monazite grains demonstrate subtle to distinct patchy zoning related to slight compositional variations. Textural and compositional characteristics indicate that the monazite formed in a single magmatic event in a slightly heterogeneous system, and was only weakly affected by secondary alteration, which did not disturb the Th-U-Pb system. Chemical dating of the monazite gave a consistent age of 299 ± 1.7 Ma. The current study presents the first geochronological data for the Stolpen granite. It provides evidence that Stolpen is the youngest Variscan granitic intrusion in the Lusatian Granodiorite Complex and indicates that magmatic activity related to post-collisional extension in this region lasted at least 5my longer than previously assumed.
    Źródło:
    Acta Geologica Polonica; 2014, 64, 4; 457-472
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monazite stability and the maintenance of Th-U-total Pb ages during post-magmatic processes in granitoids and host metasedimentary rocks: A case study from the Sudetes (SW Poland)
    Autorzy:
    Budzyń, B.
    Jastrzębski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060191.pdf
    Data publikacji:
    2016
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    monazite stability
    Th-U-total Pb dating
    Jawornik granitoids
    Kłodzko–Złoty Stok Pluton
    Orlica-Śnieżnik Dome
    Bohemian Massif
    Opis:
    The stability and maintenance of the age record of monazite during post-magmatic processes were studied in granitic and host metasedimentary rocks from the Sudetes (SW Poland). Unaltered monazite in the Kłodzko–Złoty Stok granitoid provided a Th-U-total Pb age of 329 ± 5 Ma, which was related to the late stage of pluton emplacement. In contrast, monazite in the Jawornik granitoid remained unaltered or was partially replaced by secondary phases, including (1) allanite, epidote and, occasionally, apatite; (2) cheralite, allanite and a mixture of clays, Fe oxides and possible unknown rare earth element (REE) phases; and (3) K-feldspar and cheralite with subsequent formation of titanite. Different alteration products on the thin section scale indicate the local character of the post-magmatic processes affecting monazite induced by alkali-rich fluids. The altered and unaltered monazite grains both yielded a Th-U-total Pb age of 343 ± 4 Ma. The Th-U-total Pb ages of the monazite in the accompanying metasedimentary rocks thermally affected by intruding magmas were also constrained. In the paragneiss in contact with the Jawornik granitoid, the unaltered monazite and monazite partially replaced by allanite yielded an age of 344 ± 5 Ma. The monazite from the mica schist, farther from the contact with the granitoids, exhibited an age of 336 ± 4.5 Ma. The 344–336 Ma ages exhibited a record of monazite (re)growth during prolonged Variscan metamorphism. The predominant early Viséan ages constrain the timing of the development of the Złoty Stok Skrzynka Shear Zone and the emplacement of the Jawornik granitoid intrusion. The age results, which are consistent with previous geochronology, indicate that the partial alteration of the monazite did not affect the internal domains or the maintenance of the monazite ages. Thus, this study reveals that monazite geochronology can provide meaningful data in crystalline rocks affected by fluid-induced post-magmatic processes.
    Źródło:
    Geological Quarterly; 2016, 60, 1; 106--123
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Age constraints on the Pre-Variscan and Variscan thermal events in the Kamieniec Ząbkowicki Metamorphic belt (the Fore-Sudetic Block, SW Poland)
    Autorzy:
    Jastrzębski, Mirosław
    Żelaźniewicz, Andrzej
    Budzyń, Bartosz
    Sláma, Jiří
    Konečny, Patrik
    Powiązania:
    https://bibliotekanauki.pl/articles/1836361.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    U-Pb geochronology
    LA-ICP-MS dating
    U-Th-total Pb geochronology
    EPMA dating
    microplates of the Bohemian Massif
    Kamieniec Ząbkowicki Metamorphic Belt
    Variscan metamorphism
    Opis:
    The Kamieniec Ząbkowicki Metamorphic Belt (KZMB) is a narrow zone of mainly mica schists, subordinate acid metavolcanics and scarce eclogites, sandwiched between Brunovistulia and the northern tip of the Teplá-Barrandia microplates. Locally occurring high-pressure relics indicate subduction of the metasedimentary succession of the KZMB, the origin and provenance of which remain unclear. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) investigations of detrital zircons show that the metapelites represent an Ediacaran-Cambrian sedimentary basin, with a maximum depositional age of 561±9 Ma. This basin was filled with detritus from a source or sources, composed of rocks containing zircons that are mainly Cryogenian-Ediacaran and Palaeoproterozoic in age. No younger component was found in the zircon population studied. The isotopic U-Pb LA-ICP-MS and chemical U-Th-total Pb electron probe microanalysis (EPMA) monazite geochronology data indicate an important regional tectono-metamorphic event at ca. 330 Ma. Though these data do not permit determination of the peak pressure from the peak temperature stages, the event was part of a complex collision of the Saxothuringian plate with Brunovistulia.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2020, 90, 1; 27-49
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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