engleski

Palaeoecology of the Late Badenian foraminifera and ostracoda from the SW Central Paratethys (Medvednica Mt., Croatia)

Late Badenian sediments with rich microfossil community were sampled in Lipa creek trench at the locality St. Barbara (SE Medvednica Mt., NW Croatia). Samples have been analyzed and palaeoecologically interpreted mostly on the basis of small benthic foraminifera and ostracoda. Planktonic / benthic ratio, Benthic Foraminifera number, Ostracoda number (tests/g dry sediment) and number of species of benthic foraminifera and ostracoda have been determined for each standardized sample. Dominant and common species were separated, and their variations across the profile were examined. Three diversity indices: Shannon-Wiener index, Dominance and Fisher  index have been used to define species diversity of benthic foraminifera. Dissolved oxygen indicators, Benthic Foraminiferal Oxygen Index and infauna / epifauna ratio were also estimated. The quantitative study of benthic foraminifera and ostracoda fauna’ s composition and also planktonic/benthic ratio allow the recognition of three palaeoenvironments: middle shelf, outer shelf and upper bathyal. The analyses have shown that the deepening of the depositional basin and the fluctuations of the oxygenation rate were the most important factors that influenced the distribution of the microfossil faunas. Microfossil community of the outer shelf lived under the conditions of decreased oxygen level in bottom water compared to the communities from middle shelf and upper bathyal environments.

Benthic foraminifera; Ostracoda; Palaeoecology; Biostratigraphy; Late Badenian; Medvednica Mt.; Croatia

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