A multi-proxy stratigraphic approach to the Eocene-Oligocene Transition in the Paratethyan Realm

The Eocene–Oligocene Transition (EOT, aprox. 34.5 Ma) represents a major shift from greenhouse to icehouse conditions, with major effects on ocean circulation, sedimentation and biotic communities. The continuous successions in the Eastern Carpathians (Romania), within the Vrancea Nappe, Paratethys, provide an excellent archive to investigate the interaction between global and regional changes. This study integrates sedimentological observations, calcareous nannofossil biostratigraphy and stable isotope (δ¹³C, δ¹⁸O) data to document environmental changes across the Eocene-Oligocene Transition.Sedimentological analysis is used to characterise lithofacies, depositional processes and redox conditions, with particular attention to the transition from Upper Eocene turbiditic systems to Lower Oligocene hemipelagic deposits. Calcareous nannofossil biostratigraphy provides a high-resolution age framework and allows the assessment of changes in assemblage composition, diversity and the occurrence of Paratethyan endemic taxa. Geochemical investigations include stable isotope analyses (δ¹³C, δ¹⁸O) and bulk geochemical parameters (e.g., TOC, CaCO₃) to track variations in carbon cycling, water-mass properties and depositional environments.This study aims to integrate sedimentological, palaeontological and geochemical datasets to create a multi-proxy stratigraphic framework for the EOT in the Eastern Carpathians and it will place regional environmental evolution within the context of global climatic events. The results will contribute to a better understanding of how basin restriction, tectonics and palaeogeography can modify the local response to major climate transitions.