Dating the lake histories – integrated stratigraphy and correlation of isolated paleoenvironments

The long-lived Dinaride Lake System (DLS) was a vast lacustrine environment covering an area of up to 75,000 square kilometer in today southeastern Europe. It occupied multiple tectonic depressions within the Dinaride mountain chain and was located at a crucial geographic position between Central Paratethys and Mediterranean. While the richly preserved Neogene mollusks of the Dinaride basins provide an impressive example of mollusk radiation, the strictly endemic character of these mollusks inhibits straightforward biostratigraphic correlation with regions outside the DLS. Until recently, the age of these lacustrine deposits remained enigmatic. Good constraints can, however, be obtained using magnetostratigraphic, cyclostratigraphic and radiometric dating techniques. An absolute timescale and good correlations between the different Neogene basins provide better insight in the space-time evolution of the DLS, the timing and mechanism of basin formation, and the interpretation of mollusk speciation and radiation rates.

The conducted integrative research of the last decade has allowed us to determine a detailed chronology and paleogeographic setting for different DLS basins. Those results provided a completely new insight into the evolutionary history of a unique mollusk fauna originating from that fresh-water setting. The investigations were carried out in Croatia and Bosnia and Herzegovina, where corresponding lacustrine deposits crops out in tectonic depressions of the Dinaric Alps or on isolated hills of the southern Pannonian basin. Our integrated geophysical and geochemical measurements enabled the exact age calculations delimiting the Dinaride Lake System duration to the time interval between 17 and 13 Ma, i.e. during Early to Middle Miocene, concurrent with profound extension in the neighboring Pannonian Basin. Our paleomagnetic results further indicate that the Dinarides have not experienced any significant tectonic rotation since the late Oligocene.