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Wyświetlanie 1-3 z 3
Tytuł:
Complementary data on the palynostratigraphy of the Carboniferous succession of SW Poland
Autorzy:
Górecka-Nowak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059084.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Carboniferous
palynostratigraphy
Variscan Foreland Basin
Opis:
New palynostratigraphical data concerning the Carboniferous sedimentary succession of SW Poland has been obtained from the Czerńczyce IG 1 borehole and the Brońsko boreholes on the northern slope of the Wolsztyn-Leszno High, where the oldest rocks were expected. The miospore assemblages recovered from the Czerńczyce IG 1 borehole allowed assignment of the interval studied to the Marsdenian (Namurian B) and Yeadonian (Namurian C). These results, supplemented with previous palynostratigraphical data, refute the existence of a stratigraphic gap between the early Namurian and Duckmantian (Westphalian B). The reinterpretation of the unpublished miospore results of Górecka et al. (2000b, 2001a) from the Carboniferous rocks from the Brońsko boreholes, also indicate that they should actually be assigned to the upper Marsdenian and Yeadonian. All analysed miospore assemblages are mixed and contain abundant reworked specimens. The results above complement previous opinions and permit a re-evaluation of the stratigraphy of the Carboniferous siliciclastic succession of SW Poland. Its sedimentation was certainly initiated in the earliest Namurian or earlier and probably lasted without long gaps until the Stephanian. The abundance and common occurence of reworked miospores indicate the age of rocks eroded during Carboniferous deposition. The lithological and palynofacial features of the late Namurian rocks from the Czerńczyce IG 1 borehole may be interpreted as a record of the shallowing of the sedimentary basin, including the possibility that some of the sedimentation occured in continental conditions. This means that the transition from the deep marine environment to shallow-water or even continental habitats likely had already taken place by the late Namurian. This suggestion, together with the tectonic deformation dated as post-Bolsovian, corresponds to the timing of the deposition and deformation in the German part of the Variscan Foreland Basin.
Źródło:
Geological Quarterly; 2010, 54, 3; 337-356
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:
U-Pb zircon age of the Krásné Loučky tuffite : the dating of Visean flysch in the Moravo-Silesian Paleozoic Basin (Rhenohercynian Zone, Czech Republic)
Autorzy:
Jirásek, J.
Wlosok, J.
Sivek, M.
Matýsek, D.
Schmitz, M.
Sýkorová, I.
Vašíèek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2060438.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
volcaniclastic sediment
Horní Benešov Formation
Variscan foreland
Viséan
Carboniferous
chronostratigraphy
Opis:
The only previous U-Pb zircon date for the the Early Carboniferous flysch sequence of the Moravo-Silesian Paleozoic Basin was published in 1987 from tuffogenic material from Kobylí Quarry at Krásné Loučky near the town of Krnov (Silesia, Czech Republic). The measured age of 319 Ma did not agree with its stratigraphic position, and was used as the basis for a hypothesized block of Late Carboniferous paralic molasse incorporated during a later tectonic event. During a survey of the still active quarry in 2010, volcaniclastic horizons were identified and sampled. Direct correspondence of the tuff units to those sampled in 1987 cannot be proved but is likely. High precision chemical abrasion - thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of zircon from this new material has yielded an age of 340.05 ± 0.22 Ma, which correlates to the previously inferred stratigraphic age of the locality and the current calibration of the Early Carboniferous geologic time scale. The newly established age corresponds to the Visean stage and dates the boundary between the Horní Benešov and Moravice formations that can be correlated with other foredeep basins of the Culm in the European Variscides. A population of detrital Cambro-Ordovician zircons and a single 2.0 Ga old zircon crystal from the same volcaniclastic layer dated by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) are consistent with the known age of source material in the Variscan orogenic front.
Źródło:
Geological Quarterly; 2014, 58, 4; 659--672
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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