The evolution of a key segment in the Europe–Adria collision: The Fruška Gora of northern Serbia

The large number of roll-back systems in Mediterranean orogens poses interesting questions concerning interacting extensional back-arc deformation driven by different slabs. One such area characterized by a critical lack of kinematic studies is the connection between the Carpathians and Dinarides, where the Fruška Gora is an isolated inselberg of basement and Mesozoic cover surrounded by Miocene sediments. This area recorded a complex evolution related to the Cretaceous–Paleogene collision between Europe- and Adria-derived tectonic units, the Miocene extension of the Pannonian Basin and its subsequent inversion. This evolution has been analysed in a kinematic study combined with biostratigraphic and Rb-Sr thermochronology of sediments and their metamorphism. Results demonstrate a poly-phase tectonic evolution and allowed the discrimination of deformation events and basement affinities. The protolith of the Fruška Gora metamorphic core contains a typical Triassic–Jurassic sequence of the distal Adriatic margin that is overlain by Upper Cretaceous–Paleogene sediments deposited in the Neotethys subduction zone. A part of this basement still records a Late Jurassic (~ 148 Ma) burial metamorphic event that is associated with the coeval structural emplacement of overlying oceanic crust. Three successive deformation events were associated with the Latest Cretaceous–Early Oligocene contraction. The subsequent exhumation of the Fruška Gora metamorphic core started at ~ 28 Ma in the footwall of a large extensional detachment and continued by normal faulting during Early–Middle Miocene times. The large-scale extension took place during the extension of the Pannonian Basin and was associated with coeval translations and clockwise rotations of the Fruška Gora. Its present-day antiformal geometry truncated by high-angle reverse faults with S-ward vergence was established during the inversion of the Pannonian Basin, an effect of the late stage Pliocene–Quaternary Adriatic indentation.

► Metamorphosed Mesozoic sediments with Adriatic affinity in NE Dinarides
► Extensional detachments accommodating Pannonian extension
► Pannonian extension started in Oligocene times, earlier than previously assumed
► Extensional collapse associated with large clockwise rotation