The role of the 'Zvornik suture' for assessing the number of Neotethyan oceans: Surface - subsurface constraints on the fossil plate margin (Vardar Zone vs. Inner Dinarides)

Abstract

The balancing exercise of the “single-ocean model” and reexamination of Jurassic paleogeographic conditions and tectonic interaction allowed the reconstruction of the mosaic of independent microplate margins and sutured northwestern Tethyan realm (Vardar Ocean). The overprinted Mesozoic convergent margin referred to as the ‘Zvornik suture’ was of special interest in the reconstruction of the displaced ophiolite belts of Dinarides and Vardar Zone. The surface–subsurface constraints of these mixed crustal units, in particular the polyphase strike-slip character of the ‘Zvornik suture’ yields the presence of at least two of Neotethyan basins extrapolated in the vicinity of the northwestern segment of this paleosuture - related fault system. The restoration and synopsis shows a limited capability for obduction-related emplacement of the Vardar oceanic lithosphere (West Vardar Zone) accounting the polyphased strike-slip tectonics. The balancing and the proposed tectonic/paleogeographic recon struction does not exclude obduction, but it shows a limited capability with much shorter across-strike width of the highlydeformed West Vardar ophiolite. The presence of the two distinct autochthonous Tethyan oceans divided by this important dextral strike-slip fault zone is suggested: The Inner Dinaric–(Mirdita–Pindos) Ocean or Dinaric Tethys (identified by the Inner Dinaric Ophiolite Belt) and the Vardar Ocean (identified by the West Vardar Zone). The West Vardar Zone remains to be a subzone of the principal composite Neotethyan suture referred to as the Vardar Zone s.s., whereas the Dinaric Tethys have been (re)incorporated to the area of Dinarides (Adria microplate). The northern segments of these two landlocked basins were on both sides of the Inner Dinaridic continental ridge (referred to as the Drina-Ivanjica block), divided by the protracted strike-slip activity of the ‘Zvornik suture’.