Triassic metasediments in the internal Dinarides (Kopaonik area, southern Serbia): stratigraphy, paleogeographic and tectonic significance

Abstract

Strongly deformed and metamorphosed sediments in the Studenica Valley and Kopaonik area in southern Serbia expose the easternmost occurrences of Triassic sediments in the Dinarides. In these areas, Upper Paleozoic terrigenous sediments are overlain by Lower Triassic siliciclastics and limestones and by Anisian shallow-water carbonates. A pronounced facies change to hemipelagic and distal turbiditic, cherty metalimestones (Kopaonik Formation) testifies a Late Anisian drowning of the former shallow-water carbonate shelf. Sedimentation of the Kopaonik Formation was contemporaneous with shallow-water carbonate production on nearby carbonate platforms that were the source areas of diluted turbidity currents reaching the depositional area of this formation. The Kopaonik Formation was dated by conodont faunas as Late Anisian to Norian and possibly extends into the Early Jurassic. It is therefore considered an equivalent of the grey Hallstatt facies of the Eastern Alps, the Western Carpathians, and the Albanides-Hellenides. The coeval carbonate platforms were generally situated in more proximal areas of the Adriatic margin, whereas the distal margin was dominated by hemipelagic/pelagic and distal turbiditic sedimentation, facing the evolving Neotethys Ocean to the east. A similar arrangement of Triassic facies belts can be recognized all along the evolving Meliata-MaliacVardar branch of Neotethys, which is in line with a 'one-ocean-hypothesis' for the Dinarides: all the ophiolites presently located southwest of the Drina-Ivanjica and Kopaonik thrust sheets are derived from an area to the east, and the Drina-Ivanjica and Kopaonik units emerge in tectonic windows from below this ophiolite nappe. On the base of the Triassic facies distribution we see neither argument for an independent Dinaridic Ocean nor evidence for isolated terranes or blocks.

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

“…Furthermore, the facies is similar in composition and age with the metamorphosed sediments of the distal Adriatic margin observed in the Kopaonik area (Figures 1 and 3, such as the calcareous schists of the Kopaonik Formation of Schefer et al, 2010; or the Central Kopaonik series of Sudar, 1986). Therefore, the metamorphic core must be largely attributed to the Jadar-Kopaonik unit of the internal Dinarides, given its spatial position and metamorphic facies (Figure 1).…”

The balance between orogenic building and subsequent extension during the Tertiary evolution of the NE Dinarides: Constraints from low-temperature thermochronology

“…This metamorphosed sequence is very similar, in terms of composition and thickness, to the Triassic-Jurassic metamorphosed sequence that composes the JadarKopaonik composite unit (sensu Schmid et al, 2008) observed southwards in the Dinarides area of Studenica and Kopaonik tectonic windows (Fig. 1c;Schefer et al, 2010). Recent studies of the Fruška Gora metamorphics indicate that these rocks are affected by several generations of folding and thrusting, and subsequently overprinted by pervasive Oligocene-Lower Miocene top-to-E-ENE directed shearing during the extensional formation of the Pannonian basin (Toljić et al, submitted for publication).…”

“…The same complete succession has been demonstrated to be metamorphosed to greenschist facies in the Studenica and Kopaonik windows, which are located southward, in along-strike southward prolongation of the Bukulja mountains ( Fig. 1c; Egli, 2008;Schefer et al, 2010). The similarity of the Bukulja succession in its entirety with the metamorphosed and non-metamorphosed rocks found elsewhere in similar structural position points directly to a Triassic-Jurassic Adriatic distal passive continental margin and its transition to an oceanic domain that was subducted and metamorphosed during the Late Cretaceous continental collision recorded in the Sava suture zone of the Dinarides (Schmid et al, 2008;Ustaszewski et al, 2010).…”

“…This is in agreement with the recent 82 Ma metamorphic age recorded on the calcareous schists of the Bukulja Mountains (Matenco et al, submitted for publication). The protolith of the uppermost calcareoussericitic ultramylonitic schists with quatzitic-ophiolitic detritus is interpreted as the Uppermost Cretaceous-Palaeogene sediments of the Sava zone, based on weak palaeontological evidences and lithological similarities with its non-metamorphosed counterpart (Marović et al, 2007a(Marović et al, , 2007bSchefer et al, 2010).…”

Boudins and Mullions

“…However, asymmetric boudins can be problematic shear-sense indicators (Goscombe and Passchier, 2003), thus require additional studies. Triassic limestone and dolomite (Schefer et al, 2010). Photo width ∼20 cm.…”