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Wyświetlanie 1-2 z 2
Tytuł:
Sedimentary development and isotope analysis of deposits at the Cretaceous/Palaeogene transition in the Paraíba Basin, NE Brazil
Autorzy:
Neumann, Virgínio Henrique
Barbosa, José Antônio
Nascimento-Silva, Valberlândia Maria
Sial, Alcides Nobrega
Filho, Mario
Powiązania:
https://bibliotekanauki.pl/articles/94597.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
NE Brazil
Cretaceous-Paleogene boundary
carbon isotopes
oxygen isotopes
Brazylia
izotop węgla
izotop tlenu
Opis:
New data are presented for three formations (Itamaracá, Gramame and Maria Farinha) and two boundaries (Campanian/Maastrichtian and Maastrichtian/Danian) in the Olinda Sub-basin of the Paraíba Basin. Currently accepted facies models, sequence stratigraphy characterizations, and stable-isotope data of carbon and oxygen are reviewed. The carbonate cement of the Itamaracá Formation sandstones shows carbon- and oxygen-isotope ratios consistent with a shallow-marine depositional environment: δ18O ranges from -0.8 to -2.7‰ PDB, and δ13C ranges from +1 to +2‰ PDB. Within the Itamaracá Formation, a maximum flooding surface at the Campanian/Maastrichtian transition has been identified. During the Maastrichtian, a Highstand System Tract was deposited, which shows an increase in temperature and marine bioproductivity as recorded by stable-isotope values (δ18O from -3 to -5‰ PDB, and δ13C values of -1.2, -0.3, 0.1 and +2.3‰ PDB). Just below the K/Pg boundary, the O-isotope signal indicates three warming phases, alternating with four cooling phases.
Źródło:
Geologos; 2009, 15, 2; 103-113
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in paleo-circulation and the distribution of ammonite faunas at the Coniacian–Santonian transition in central Poland and western Ukraine
Autorzy:
Remin, Z.
Gruszczyński, M.
Marshall, J. D.
Powiązania:
https://bibliotekanauki.pl/articles/139412.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Coniacian–Santonian transition
paleogeography
paleo-circulation
ammonites
carbon stable isotopes
oxygen stable isotopes
paleogeografia
amonity
izotopy węgla
izotop tlenu
Opis:
Ammonite distribution patterns and carbon and oxygen stable isotopes from the Lipnik-Kije (Poland) and Dubovcy (Ukraine) sections allow us to propose a model of sea water paleo-circulation in central Europe for the Coniacian-Santonian interval. The tectonic evolution of the south-eastern part of Poland, and expansion of the Krukienic Island areas, appears to have been one of the most important factors affecting paleotemperatures and the distribution of ammonite faunas in the shallow, epicontinental sea in this part of Europe. In the Lipnik-Kije section, low-latitude Tethyan ammonites, especially of the genera Nowakites, Parapuzosia and Saghalinites, are mixed with the cold water loving ammonite genus Kitchinites in the Lower Santonian. In the Dubovcy section (western Ukraine), Tethyan ammonites disappear abruptly in the earliest Santonian, giving place to temperate ammonites of the Kitchinites group in the early Early Santonian and to Boreal belemnites of the genus Gonioteuthis in the Middle and Late Santonian. Despite evidence for the effects of diagenesis in both sections, bulk-rock δ18O records from the limestones support higher seawater paleotemperatures in the Polish sea and cooler conditions in the western Ukraine. The proposed paleo-circulation model and paleotemperature distribution across Europe is supported independently by changes in faunal and nannoflora evidence (ammonites, foraminifera and nannoplankton), and rather unexpectedly with the bulk δ18O data. These data allow the recognition of the end-Coniacian–Early Santonian cooling event, resulting from cold currents flowing from the north, which is traceable, with different magnitude, in several European sections. Facies changes in both sections are related to the input of terrigenous material, and linked to Subhercynian tectonic movements which affected the eastern (Ukrainian) and central (Holy Cross) segment of the Mid Polish Trough at different times. Uplift and sediment input moved westwards through time. Clastic input is detectable at the Coniacian–Santonian boundary in the Ukrainian segment. Similar facies changes reached the Holy Cross segment in Poland distinctly later, somewhen in the Middle Santonian. It is likely that tectonics together with paleo-circulation changes markedly restricted or even cut-off the western Ukraine area from Tethyan ocean influences in the Early Santonian.
Źródło:
Acta Geologica Polonica; 2016, 66, 1; 107-124
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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