engleski

Paleoenvironmental reconstruction of the middle Eocene Pazin Basin (Croatia)

Assemblages of benthic foraminifera from two clastic successions from the Pazin Basin (central Istria, Croatia) were investigated to reconstruct paleoenvironmental conditions during the Middle Eocene time. The prevalence of epifaunal foraminifera indicates good ventilation of the bottom water caused by the morphology of the basin, which was elongated and open on both sides enabling the undisturbed flow of the water all the way through. The depth of deposition is inferred from the bathymetric distribution of the individual taxa and estimated to be 200-300 m in the lowermost part of the Globigerina Marls whereas in the lower part of Flysch deposits indicate deepening to more than 500 m. The assemblages imply generally mesotrophic environmental conditions with variable organic flux. The transition to flysch-type sedimentation (E11 Zone) is marked by a composition changes probably caused by the input of irregular supply of more partially degraded and suspended organic matter carried from the shelf by turbidity currents. In the upper E13 Zone foraminiferal assemblages indicate decreased oxygenation that might have been a result of the reduced circulation caused by the beginning of the closure of the basin at the end of E13 Zone.

foraminifera; Eocene; paleoenvironment

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