Intraoceanic subduction of the northwestern Neotethys and geodynamic interaction with Serbo-Macedonian foreland: Descending vs. overriding near-trench dynamic constraints (East Vardar Zone, Jastrebac Mts., Serbia)

Abstract

A composite paleogeographic and plate kinematic spatiotemporal reconstruction of the exhumed Neotethyan cross-lithospheric footwall amalgamation (Jastrebac dome) incorporates the two formerly underplating oceanic entities, West Vardar and East Vardar Zone. These ophiolite-bearing agglomerations are unroofed within the accretionary Paleogene to Miocene core-complex, beneath the Serbo-Macedonian overriding plate. The exposed Neotethyan crustal amalgamation is comprised of: an (i) folded trench assemblage of uncertain Mesozoic? Paleogeographic affinity metamorphosed under a greenschist-grade (West-vs. East Vardar Zone or Neotethyan crust-vs. its back-arc system?) sandwiched beneath the overlying (ii) late Cretaceous – Paleogene (meta)turbidites. To make matters more intricate, at the closest proximity of the dome (Mali Jastrebac Mountain) there is a similar (iii) greenschist-facies amalgamation comprised of the Neoproterozoic – Lower Paleozoic ocean-floor assembly (Supragetic basement). The interpretations of this rather controversial cross-lithospheric structure include a reassessment of the obduction sequence, and are underpinned by the restoration of the near-trench microplate motions. The study addresses the (1) local finite configuration (Serbo-Macedonian hanging wall vs. Neo - tethyan intraoceanic arc) and the (2) spatiotemporal geometry of the principal (micro)plate boundaries (Serbo-Macedonian Unit vs. Apulia/Adria). Unlike the earlier proposal of the ophiolite obduction onto the Serbo-Macedonian Unit onto the Apulia/Adria hinterland (or external segment of the “Dacia mega-terrane”), we here propose a west-vergent obduction of the East Vardar Zone ophiolites onto the descending Neotethyan lithosphere (West Vardar ophiolites) - a similar scenario to its continuation in Greece (Peonias subzone).