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Wyszukujesz frazę "Pomeranian Caledonides" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Pomeranian Caledonides (NW Poland), fifty years of controversies: a review and a new concept
Autorzy:
Dadlez, R.
Powiązania:
https://bibliotekanauki.pl/articles/2059454.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Caledonides
Pomeranian Caledonides
Rügen
tectonics
terranes
Opis:
The results of a half-century investigations of the Pomerania-Rügen Caledonides are reviewed. Fifty years ago there were two rival hypotheses based exclusively on analyses of gravity and magnetic data. One of them assumed the presence of the so-called Circum-Fennosarmatian Caledonides, the second one claimed that the Precambrian craton of the eastern Europe extends far to the west reaching northern Germany and Pomerania. As time passed, more new facts from boreholes and seismic refraction and reflection studies accumulated. New hypotheses appeared, namely the concepts of an aulacogen and a major strike-slip fault, now merely of a historical importance. In spite of the new data the principal dilemma remains the same until present. Some investigators believe that the East European Craton (Baltica) extends far to the south-west reaching the Elbe-Odra Line, others assume the presence of the Caledonian deformations in Rügen and Pomerania which are regarded - according to modern concepts - as a manifestation of terrane tectonics. The latter group of hypotheses is supplemented by the author with the model of proximal terranes detached from the craton margin farther to the south-east and then re-accreted. The hypothesis is based on an analysis of differences in crustal structure in northern Germany and western Poland, and on the concept of a counter-clockwise rotation of Baltica during the Ordovician, proved by palaeomagnetic data.
Źródło:
Geological Quarterly; 2000, 44, 3; 221-236
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acritarch assemblages from the Silurian Pomeranian Caledonides and their foreland
Autorzy:
Jachowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059448.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Pomeranian Caledonides
Silurian
acritarch assemblages
Opis:
Comprehensive palynological studies of the Silurian rocks of the Pomeranian Caledonides are described, the first since Eisenack's (1972) work. 250 clastic rock samples were analysed, all from deep boreholes. Three of these boreholes (Lębork IG 1, Gdańsk IG 1 and Kościerzyna IG 1) are located NE of the Teisseyre-Tornquist Zone (TTZ) and contain horizontal successions of the western, marginal part of the East European Craton. Other boreholes studied (Bydgoszcz IG 1, Klosnowo IG 1 and Stobno 1) penetrated folded Lower Palaeozoic sediments, and lie SE of the TTZ. The investigations included a complete Silurian profile from the Llandovery to the Poidoli, which is documented in detail by graptolites. Associations of microflora (Acritarcha, Prasinophyceae, Sporites) and microfauna (Chitinozoa, Scolecodonta) varied in quality and quantity. There was considerable variability in the preservation and thermal maturity of the organic-walled microfossils. Detailed investigations of the acritarchs are described. 7 characteristic acritarch assemblages have been distinguished, and these are correlated with the graptolite biozones. Llandovery rocks contain assemblages with Domasia, Ammonidium and Tylotopalla genera. Wenlock deposits include Tylotopalla, Leptobrachion and Cymbosphaeridium. The Upper Ludlow deposits contain well preserved assemblages with Visbysphaera, Veryhachium, Onondagella and Leoniella, accompanied by Neoveryhachium carminae, Geron gracilis, and some Deflandrastrum and Visbysphaera species generally considered characteristic of Gondwana. Throughout the Silurian profile, individual specimens of typical Ordovician genera such as Acanthodiacrodium, Frankea, Striatotheca and Coryphidium occur. The acritarch assemblages overall show mixed characters, typical of both Baltica and Gondwana.
Źródło:
Geological Quarterly; 2000, 44, 3; 317-331
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Ordovician acritarchs of the Pomeranian Caledonides and their foreland - similarities and differences
Autorzy:
Szczepanik, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2059446.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Peribaltic Syneclise
West Pomeranian Caledonides
Ordovician
acritarchs
stratigraphy
thermal maturity
Opis:
Ordovician acritarch assemblages of the West Pomeranian Caledonides and their platformal foreland in the Peribaltic Syneclise immediately adjoining the T-T Zone were investigated. Material come from the Ordovician section of the Kościerzyna IG 1, Lębork IG 1 and Gdańsk IG 1 boreholes drilled in the marginal part of the East European Craton, though acritarchs were found only in two samples from the Gdańsk IG 1 borehole. In general, microflora was abundant and the investigations supported current ideas on the stratigraphical level of these rocks. The acritarch assemblages from the Gdańsk IG 1 borehole, found at a depth of 3214.8 m, contain species of Baltisphaeridium, characteristic of the Llanvirn and described by Górka from the eastern part of the Peribaltic Syneclise and the Podlasie Depression. The abundant microflora from West Pomerania contains index taxa of the uppermost Llanvirn (Llandeilo) and Caradoc. Numerous palynomorph associations from the Ordovician rocks of the Koszalin-Chojnice Zone can be divided into three local microfloral zones, using quantitative data, and these may be useful for local stratigraphical correlations. Acritarch assemblages on either side of the T-T Zone show many similarities and suggest that, in the late Llanvirn and Caradoc, there was little palaeogeographic separation between the sedimentary basins of Baltica and West Pomerania; at least, their palaeolatitudinal positions were similar. The thermal maturity of Ordovician organic matter (low and moderate) is also similar in both these areas. The highest heat flow values seem to be characteristic of the western part of the Peribaltic Syneclise, adjoining the T-T Zone. The degree of their thermal alterations in the West Pomeranian Caledonides is surprisingly low when the strong tectonic deformation and considerable depth of the Ordovician rocks are taken into account. The high morphological diversity of the acritarch assemblages, the presence of Baltisphaeridium and Ordovicidium, and especially of abundant Veryhachium, suggest that microflora from the Koszalin-Chojnice Zone represents an open-marine depositional palaeoenvironment, distant from the coast.
Źródło:
Geological Quarterly; 2000, 44, 3; 275-295
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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