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Wyszukujesz frazę "Maastrichtian" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
The Belemnitella stratigraphy of the Upper Campanian : basal Maastrichtian of the Middle Vistula section, central Poland
Autorzy:
Remin, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2059997.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Campanian
Maastrichtian
Vistula section
belemnites
biostratigraphy
artificial Neural Networks
Campanian-Maastrichtian boundary
Opis:
This taxonomy and stratigraphy of the Upper Campanian and Lower Maastrichtian Belemnitella lineages, from the Middle Vistula sections, based on new collections, is presented. The correlation to the basal Maastrichtian standard GSSP at Tercis, France, is provided based on inoceramid bivalve stratigraphy. The Artificial Neural Networks (ANN), particularly the self-organizing Kohonen algorithm, was applied to taxonomic discrimination. Eight morphotypes within the genus Belemnitella, understood here as natural species populations, were recognised. Five of these are assigned to known taxa: Belemnitella mucronata, B. posterior, B. minor [= B. minor I and B. minor II], B. langei and B. najdini; and three, B. sp. a, B. sp. 1 and B. sp. 2, are left in open nomenclature. Four Belemnitella zones are proposed. Due to its palaeogeographic position, between Western and Eastern Europe, the Middle Vistula section is characterized by the co-occurrence of Belemnitella species from those two areas. Consequently, it enables better correlation of Belemnitella-based schemes; the East European B. najdini and B. posterior are placed next to West European B. minor chronospecies I and II. The Campanian/Maastrichtian boundary, as currently defined, is placed at the top of the najdini – posterior Zone, which is an equivalent of the Belemnella-based boundary, i.e. at the base of the Belemnella obtusa / Belemnella vistulensis zones. Within the top of the najdini – posterior Zone occurs a level (an interval of only a few metres), where nearly all of the Upper Campanian Belemnitella disappear. This level coincides with taxonomic changes observed within the co-occurring representatives of genus Belemnella.
Źródło:
Geological Quarterly; 2015, 59, 4; 783--813
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Belemnella stratigraphy of the Campanian-Maastrichtian boundary; a new methodological and taxonomic approach
Autorzy:
Remin, Z.
Powiązania:
https://bibliotekanauki.pl/articles/138983.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
belemnity
biostratygrafia
kampan
Kronsmoor
mastrycht
sztuczne sieci neuronowe
Wisła
Artificial Neural Networks
belemnites
biostratigraphy
Campanian
Campanian-Maastrichtian boundary
Kronsmoor section
Maastrichtian
Vistula section
Opis:
The taxonomy and stratigraphy of the Upper Campanian and Lower Maastrichtian belemnites from the Vistula (central Poland) and Kronsmoor (northern Germany) sections are revised on the basis of new collections from the Vistula section as well as a reinvestigation of the classic collection of Schulz from the Kronsmoor section. For the taxonomic description a new biometric procedure is proposed, which can be applied to both the genera Belemnella and Belemnitella. For the species-level taxa recognition the Artificial Neural Networks method, the self-organizing Kohonen algorithm, was implemented. This new taxonomic and methodological approach enabled the recognition of nine species of the genus Belemnella. Five of them can be assigned to the existing species B. lanceolata, B. longissima, B. inflata, B. obtusa and B. vistulensis. However, the species concept differs from that applied by Schulz (1979). As a consequence, the stratigraphic ranges of these species are modified. Four species are left in open nomenclature and represent possibly new species. Future studies may reveal that they might be assigned to East European forms from Ukraine or Russia. The species of Belemnella recognized are placed into the stratigraphic framework based on the standard ammonite and inoceramid bivalve zonations, especially those recognized in the Vistula section. The newly proposed belemnite zonation for the Vistula and Kronsmoor sections is correlated via inoceramids with the standard GSSP at Tercis, France, in order to identify the base of the Maastrichtian Stage. The Campanian/Maastrichtian boundary as defined in Tercis is placed here at the base of the newly defined B. obtusa and B. vistulensis Zones ["obtusa/vistulensis"] - thus it is markedly higher than the traditional boundary based on the FAD of representatives of the genus Belemnella - This new boundary coincides well with a distinct turnover of belemnite guard morphology and represents one of the most important points in the early evolutionary history of Belemnella. Three belemnite zones defined by their lower boundaries are recognized in the Campanian/Maastrichtian interval, in addition to three subzones recognized within the B. obtusa Superzone. The B. lanceolata and B. inflata zones as understood here are referred to the Upper Campanian [Tercis definition]. The B. obtusa Zone is subdivided into three subzones, viz.: Belemenlla vistulensis, Belemnella sp. G and Belemnella sp. F, which are referred to the Lower Maastrichtian [Tercis definition]. The fast evolving species of Belemnella enable the proposal of a biostratigraphic scheme with a resolution that is higher than those based on inoceramid bivalves and ammonites - the longevity of a belemnite zone could be as low as 200Ky.
Źródło:
Acta Geologica Polonica; 2012, 62, 4; 495-533
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early representatives of the belemnite genus Belemnella (Cephalopoda) from the uppermost Campanian-Lower Maastrichtian of the Middle Vistula River section, central Poland
Autorzy:
Keutgen, N.
Remin, Z.
Walaszczyk, I.
Powiązania:
https://bibliotekanauki.pl/articles/139049.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Belemnella
biostratygrafia
Campanian-Maastrichtian boundary
kampan
mastrycht
Wisła
biostratigraphy
Middle Vistula River section
Species concepts
Opis:
Representatives of the belemnite genus Belemnella from the uppermost Campanian and lowermost Maastrichtian of the Middle Vistula River Valley section (central Poland) have been studied, using the species concept proposed by Schulz in 1979. Results have been compared to a recently proposed new interpretation of the genus Belemnella based on artificial neural networks, as put forward by Remin in 2007 and 2012. In the interval studied, four taxa have been recognised: Bln. longissima, Bln. inflata, Bln. obtusa and Bln. vistulensis, the last-named being a senior synonym of Bln. pseudobtusa. Three additional forms have been left in open nomenclature: Bln. cf. lanceolata, Bln. ex gr. lanceolata/inflata and Belemnella sp. Based on their documented vertical ranges, three Belemnella standard zones, as originally distinguished in the Kronsmoor section by Schulz (1979), northern Germany, have been defined, in ascending order: the Bln. lanceolata, Bln. vistulensis and Bln. obtusa zones. The bases of the lanceolata and obtusa zones in the Middle Vistula River Valley section can be directly correlated with the same zones at Kronsmoor, and appear to be isochronous within limits of stratigraphic resolution. The base of the vistulensis Zone (Bln. vistulensis according to the species concept of Schulz in 1979), however, is probably diachronous, being older in the Middle Vistula section. Although Schulz's and Remin's species concepts differ quite considerably, they do result in similar stratigraphic subdivisions of the Kronsmoor and Middle Vistula River sections.
Źródło:
Acta Geologica Polonica; 2012, 62, 4; 535-559
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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