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Wyszukujesz frazę "diatoms" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Late Maastrichtian foraminiferids and diatoms from the Polish Carpathians (Ropianka Formation, Skole Nappe): a case study from the Chmielnik-Grabówka composite section
Autorzy:
Gasiński, M. A.
Olshtynska, A.
Uchman, A.
Powiązania:
https://bibliotekanauki.pl/articles/138777.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Carpathians
Skole Nappe
Cretaceous
microfossils
plankton
foraminiferids
diatoms
flysch
Karpaty
płaszczowina skolska
kreda
mikroskamieniałości
okrzemki
flisz
Opis:
Well-preserved foraminiferids have been found in the Chmielnik-Grabówka section (Skole Nappe, Polish Carpathians). The Abathomphalus mayaroensis (late Maastrichtian) and Racemiguembelina fructicosa (earlylate Maastrichtian) standard planktonic foraminiferal biozones have been recognized, based on the occurrence of their respective index species. Sediments of the R. fructicosa Zone contain diatoms, which are a rare component of Cretaceous flysch microfossil assemblages in the Carpathians. The diatom frustules and some foraminiferid tests are pyritized, probably after burial in the sediment, below the redox boundary or in the oxygen-deficient microenvironment inside the frustules or tests of microfossils; the presence of trace fossils and bioturbational structures in the same bed indicate an oxygenated sea floor.
Źródło:
Acta Geologica Polonica; 2013, 63, 4; 515-525
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
From museum drawers to ocean drilling: Fenneria gen. nov. (Bacillariophyta) offers new insights into Eocene marine diatom biostratigraphy and palaeobiogeography
Autorzy:
Witkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/138695.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Triceratium barbadense
Triceratium brachiatum
Triceratium inconspicuum
Triceratium kanayae
Palaeogene
fossil diatoms
taxonomy
biostratigraphy
palaeobiogeography
okrzemki
paleogen
taksonomia
biostratygrafia
paleobiogeografia
Opis:
Triceratium barbadense Greville, 1861a, T. brachiatum Brightwell, 1856, T. inconspicuum Greville, 1861b and T. kanayae Fenner, 1984a, are among the most common diatoms reported worldwide from lower to middle Eocene biosiliceous sediments. Due to complicated nomenclatural histories, however, they are often confused. A morphometric analysis performed herein indicates that T. brachiatum is conspecific with T. inconspicuum, and that both were previously often misidentified as T. barbadense. Triceratium barbadense sensu stricto is a distinct species similar to Triceratium castellatum West, 1860. Triceratium brachiatum and T. kanayae are transferred herein to a new genus, Fenneria, for which a close phylogenetic relationship with Medlinia Sims, 1998 is proposed. A review of the geographic and stratigraphic distribution of Fenneria shows that the best constrained records of its occurrences are found at DSDP Site 338, and ODP Sites 1051 and 1260. The ages of the base (B) and top (T) of each species’ stratigraphic range are calibrated here to the Geomagnetic Polarity Timescale either directly or inferred via correlation with dinocyst biostratigraphy. Latitudinal diachroneity of ~7 million years is documented for F. brachiata, which disappears earlier in tropical and mid-latitude sites than in the northern high latitudes. These observations, coupled with a preliminary compilation of the Chron C20n taxonomic composition of pelagic diatom assemblages for Sites 338, 1051 and 1260, indicate that diatoms diversified palaeobiogeographically considerably earlier than the Eocene-Oligocene Transition, as commonly believed. This study also emphasizes the importance of the detailed examination of specimens from both museum collections and deep-sea cores as a step toward enhancing the utility of Palaeogene diatoms in palaeoceanographic and palaeoenvironmental reconstructions.
Źródło:
Acta Geologica Polonica; 2018, 68, 1; 53-88
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Pliocene calcareous and siliceous microfossils of the Sawai Bay Formation, Car Nicobar Island, northern Indian Ocean
Autorzy:
Chakraborty, Arindam
Ghosh, Amit K.
Mccartney, Kevin
Saxena, Stuti
Dey, Rikee
Roy, Lopamudra
Powiązania:
https://bibliotekanauki.pl/articles/1835597.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Zanclean
calcareous nannofossils
radiolarians
diatoms
silicoflagellates
sponge spicules
Andaman islands
Nicobar islands
India
nanoplankton wapienny
radiolarie
okrzemki
wyspy Andaman
wyspy Nicobar
Indie
Opis:
The present contribution provides a study of calcareous nannofossils and siliceous microfossils from the Sawai Bay Formation on Car Nicobar Island, northern Indian Ocean. Two stratigraphically short sediment intervals near Sawai Bay have been examined. Qualitative and quantitative microfossil analyses show the Sawai Bay ‘A’ Section to be devoid of siliceous microfossils, while 24 well-preserved calcareous nannofossil taxa are identified. The Sawai Bay ‘B’ Section yields 18 calcareous nannofossil, 33 radiolarian and 25 diatom taxa. The calcareous nannofossil index taxa (Ceratolithus armatus Müller, 1974a and C. cristatus Kamptner, 1950) indicate both sections to be from zones NN12 (CN10b) and NN13 (CN10c) of early Pliocene (Zanclean) age. The radiolarian taxa, i.e., Didymocyrtis avita Riedel, 1953, Euchitonia spp., Siphocampe lineata (Ehrenberg) Nigrini, 1977, Stichocorys peregrina Riedel, 1953, Semantis spp. and Stylochlamydium sp. are common in the Sawai Bay ‘B’ Section, which is assigned to Zone RN9. Most of the diatom taxa are represented by rep-resentatives of the genera Actinocyclus Ehrenberg, 1837, Azpeitia Peragallo in Tèmpere and Peragallo, 1912, Coscinodiscus Ehrenberg, 1839a, Grammatophora Ehrenberg, 1841 and Triceratium Ehrenberg, 1839b, with the benthic diatom species Triceratium favus Ehrenberg, 1839b being predominant (~35% of the total diatom count). Siliceous microfossils are also represented by silicoflagellates dominated by Dictyocha spp. and sponge spicules dominated by astrophorids.
Źródło:
Acta Geologica Polonica; 2021, 71, 2; 175-198
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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