Upper Cretaceous Depositional and Biotical Changes in the Gosau-Type Basins of the Getic Depression

Abstract

This paper is focussed on the Upper Cretaceous successions that crop out in the central part of the Getic Depression (the Foreland of the Southern Carpathians). We have studied various aspects related to the litho- and biostratigraphy (based on calcareous nannofossils analysis) of outcrops situated in the Codricului, Olt, and Muereasca valleys. The identified rich and diversified nannofossil assemblages allow pointing out the biozones covering several intervals of the Upper Cretaceous (upwards the Coniacian stage). A progressive deepening of depositional basin belonging to the Getic Depression was observed from the Coniacian, constitutes of shallow-marine deposits, towards the end of the Maastrichtian, composed of a deep-marine facies. These features allow recognizing the Lower Gosau and Upper Gosau Subgroups in the studied area. Based on the observed changes, we advance hypotheses about the regional sea-level fluctuation that probably mirror the tectonics of those times.