Abstract
This thesis presents new and re-evaluated chronostratigraphic data on early-middle Miocene (18-12 Ma) marine to lacustrine basins in Central Europe. The data are used to better reconstruct geodynamic, glacio-eustatic and paleoclimatic factors that drove the main paleoenvironmental changes in the Paratethys region. The first chapters showcase the main dating methods
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used for this research: magnetostratigraphy and 40Ar/39Ar dating. We defined and discussed common problems with paleomagnetism in iron sulfide-bearing sediments. The studied sequence from Lake Pannon was magnetostratigraphically correlated between ~9 and 7 Ma. The new 40Ar/39Ar age results from ashes of three marine intervals from the Pannonian Basin highlight important differences between single and multiple grain radioisotopic datasets. The subsequent chapters focus on dating and reconstructing key events in seas and lakes of Central Europe. The age of the final sea retreat of the ‘Ottnangian Sea’ from the North Alpine Foreland Basin (Ch4) was magnetostratigraphically dated at ~16.6 Ma by using eleven drill cores covering the transition from marine to brackish to freshwater environments (S German Molasse Basin). The new data imply that the late Burdigalian regression was not controlled by eustatics but by tectonics. In Chapter 5, we present an integrated magneto-biostratigraphic framework for the rise and demise of the freshwater environments of the Sarajevo-Zenica Basin in the Dinarides (<18.5 – 15 Ma). The early-middle Miocene syn-sedimentary extension phase overlapped with the Miocene Climatic Optimum and the main lake phase of the Dinaride Lake System. In contrast, radioisotopic dating and magnetostratigraphy (Ch6) revealed that neighboring Lake Popovac (Serbia) thrived after the climatic optimum (~14.6 and 14.2 Ma). This lake basin was mostly sustained by syn-rift extension of the southern Pannonian Basin. In the East Carpathian Foredeep and Transylvanian Basin, the Badenian marine transgression was dated by Mediterranean biostratigraphy to be between 14.9 and 14.4 Ma, correlating to a phase of marine overflow into the Eastern Paratethys (Tarkhanian Stage). This mid-Langhian transgression was likely assisted by a relative sea level rise. Chapter 8 presents a unique high-resolution bio-magnetostratigraphic record on a Badenian succession in the southern Pannonian Basin (Ugljevik). The basal marine flooding occurred at 14.2 Ma; slightly later than in the rest of the Central Paratethys. A temporary shift to carbonate deposition (~13.8 Ma) followed by cooler water with enhanced vertical stratification reflected the Mi3b sea level drop and subsequent restricted phase, and partially overlapped with the Badenian Salinity Crisis in the Carpathian Foredeep (13.8-13.3 Ma). The Badenian-Sarmatian Extinction Event in the top of the section was correlated to ~12.6 Ma. Finally, we stress that the sea-land configuration in the Miocene of Central Europe was mainly governed by geodynamic processes, and that it is essential to integrate those into paleogeographic maps and gateway reconstructions. We recommend that Central Paratethys stages should not be used to refer to age, but only to refer to specific paleoenvironmental phases, which might be diachronous.
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