Palaeoenvironmental changes in the Transylvanian Basin during the Early Miocene revealed by the foraminifera assemblages

The evolution of the Transylvanian Basin during the Early Miocene has been reconstructed from the succession of palaeoenvironments inferred from sedimentological trends and the succession of specific foraminiferal assemblages from Lower Miocene Tihau section in the northwestern Transylvanian Basin. Planktonic foraminifera suggest a Burdigalian age and record sea level changes, climatic and productivity events. Benthic foraminifera offer data on the palaeoenvironmental evolution, with a large-scale progradational (coarsening up) sedimentary succession influenced by regional tectonics. The succession of depositional events includes: (1) transgressive coarse grained deposits with typical Mediterranean assemblages of bivalves in beach environments; (2) a glauconitic facies which can be associated with the maximum flooding surface of the transgression; (3) sedimentation continued on a narrow shelf influenced by deltas during the highstand; (4) the influence of regional tectonics and subsequent filling with turbidites associated with fan deltas.