- Tytuł:
- The earliest Badenian Planostegina bloom deposit : reflection of an unusual environment in the westernmost Carpathian Foredeep (Czech Republic)
- Autorzy:
-
Kopecká, J.
Holcová, K.
Nehyba, S.
Hladilová, Š.
Brzobohatý, R.
Bitner, M. A. - Powiązania:
- https://bibliotekanauki.pl/articles/2059359.pdf
- Data publikacji:
- 2018
- Wydawca:
- Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
- Tematy:
-
Middle Miocene
Central Paratethys
siliciclastic sedimentation
carbonate sedimentation
large benthic foraminifera
palaeoecology - Opis:
- The Miocene sedimentation history of the Brus denudation relict (the western part of the Carpathian Foredeep, Czech Republic) has been inferred from 20 m of silt/siltstones, sand/sandstones and limestones penetrated by the Brus-1 borehole. Detailed multiproxy lithofacies and biofacies analyses have allowed facies and palaeoenvironment interpretations. The presence of molluscs, brachiopods and fish fauna, as well as large benthic and epiphytic foraminifera indicates a generally shallow, subtropical, marine environment. Despite the scarcity of biostratigraphical markers, the section can be correlated with the lowermost Badenian (~15-16 Ma). In the siltstones in the lower part of the borehole, there are abundant low-salinity foraminifera, which may indicate increased rainfall. Linked to this is the nutrient enrichment of the sea bottom water inferred from the presence of the high-nutrient taxa accompanied by abundant calcareous nannoplankton eutrophic taxa such as Coccolithus pelagicus and eutrophic planktonic foraminifera of the Globigerina bulloides/praebulloides group. The main Planostegina bloom was recorded in a sandstone in the interval 12.5-7 m, and was not influenced by a shift from high-organic content Valvulineria assemblage of small foraminifera to an epiphytic one. The boundary between siliciclastic and carbonate sedimentation (-7.5 m) shows a drop in K and Th concentrations, and in the Th/U ratio, but a rise in the Th/K ratio. This change in radioactive element content may generally indicate a significant decrease in terrestrial sediment input which is further supported by the onset of limestone deposition. Reversal of the deposition regime and a decrease of clastic input into the basin may be related to the changing of the precipitation regime, probably triggered by orbitally-forced cyclicity.
- Źródło:
-
Geological Quarterly; 2018, 62, 1; 18--37
1641-7291 - Pojawia się w:
- Geological Quarterly
- Dostawca treści:
- Biblioteka Nauki
Artykuł