VÝSLEDKY VÝZKUMU HRANICE KŘÍDA/TERCIÉR V MAGURSKÉM FLYŠI U UZGRUNĚ

Miroslav Bubík, Marie Adamová, Marta Bąk, Juraj Franců, Przemyslaw Gedl, Radek Mikuláš, Lilian Švábenická, Alfred Uchman

Abstrakt

The Cretaceous/Cenozoic transition was studied in the deep-sea/sub-CCD flysch sediments of the Carpathian Flysch using micropaleontology, sedimentology and geochemistry. The position of the boundary was estimated in the section based on integrated stratigraphy (chemostratigraphy and biostratigraphy: calcareous nannofossils, dinocysts, foraminifers, and radiolarians). The boundary layer itself was not found, but a weak Ir enrichment in three muddy turbidites is interpreted as reworking of it. The base of the benthic foraminifer Rzehakina fissistomata zone was recorded 2.5 m below the boundary. The last occurrence of the nannofossil Micula prinsii and planktonic foraminifer Abathomphalus mayaroensis was recorded in the highest calcareous turbidite mudstone 0.65 m below the boundary, and Maastrichtian radiolarian assemblage of the Amphipyndax tylotus Zone 1.45 m below the boundary. The dinocyst index species Carpatella cornuta was found just 35 cm above the base of the Ir bearing turbidite layer. No extinctions among benthic foraminifers were observed at the boundary. The dinocyst record shows prolonged stepwise return across the whole studied section (uppermost Maastrichtian - basal Danian). This multidisciplinary study has allowed the modelling of paleoenvironmental changes across the Cretaceous/Tertiary transition. The changes in the deep sea Magura Flysch Basin result from the interplay between a trend of increasing bottom-water oxygenation with two low-oxygen episodes in the uppermost Maastrichtian, the formation of an oxygen minimum zone in the water column above, increasing plankton productivity, possible upwelling, and shifts in the level of the CCD. At the boundary itself there was no sudden change, but rather a prolonged trend of increasing primary as well as benthic

Bibliografická citace

Bubík, M., Adamová, M., Bąk, M., Franců, J., Gedl, P., Mikuláš, R., Švábenická, L., & Uchman, A. (2016). VÝSLEDKY VÝZKUMU HRANICE KŘÍDA/TERCIÉR V MAGURSKÉM FLYŠI U UZGRUNĚ. Geologické výzkumy na Moravě a ve Slezsku, 9. Získáno z https://journals.muni.cz/gvms/article/view/4979

Klíčová slova

KT boundary; stratigraphy, Ir anomaly; extinction; palaeoenvironmental analysis; Outer Carpathian Flysch; Rača Unit

Plný Text:

Reference

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