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)

Darko Spahić; Tivadar Gaudenyi

doi:10.2298/GABP1902065S

Darko Spahić Geological Survey of Serbia, Rovinjska 12, 11000 Belgrade, Serbia
Tivadar Gaudenyi Geographical Institute “Jovan Cvijić” of the Serbian Academy of Sciences and Arts, Djure Jakšića 9, 11000 Belgrade, Serbia

DOI: https://doi.org/10.2298/GABP1902065S

Keywords: Jastrebac metamorphic complex, East Vardar Zone, intraoceanic subduction, retreating collision, west-vergent nappe

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).