Neogene–Quaternary structures in the border zone between Alps, Dinarides and Pannonian Basin (Hrvatsko zagorje and Karlovac Basins, Croatia)

Abstract

Analysis of Neogene–Quaternary structures from seismic lines, surface measurements and geological-mapping is presented from the border zone between the Alps, Dinarides and Pannonian Basin. First, Early Miocene extension was possibly characterised by ENE directed extension. It was partly synchronous with NW–SE shortening. Second, Middle Miocene extension was possibly characterised by NW–SE to WNW–ESE directed extension. Again, this event was followed by a new generation of thrusts related to end-Sarmatian shortening. The last, Late Miocene E–W to WNW–ESE directed extension was followed by a final shortening that created major, map-scale folds, basement pop-ups and inverted former basins. Geometry, onlap and thickness patterns of the youngest syn-tectonic basin fill indicate that this last, N–S to NW–SE directed shortening started in Late Pontian and continued up to the present time. When taking into account the wider surrounding area, it seems that the structures related to this latest shortening are arranged in often perpendicular directions, centred at the eastern end of the Periadriatic lineament. To explain this fan-like pattern of synchronous shortenings a kinematic model is proposed combining counter-clockwise rotation with north- or northwestward shift of the Dinaridic block with respect to the more stable Alpine buttress.