Tithonian limestone as a marker of early contraction of NeoTethyan Vardar Ocean: structural constraints on the latest Jurassic–earliest Cretaceous “docking” (Dobroljupci, Kuršumlija, Jastrebac Mt., Serbia)

Abstract

The Jurassic–Cretaceous East Vardar Zone (EVZ) is a NNW–SSE-directed NeoTethyan back-arc crustal amalgamation that passes through Romania, Serbia, Bulgaria, North Macedonia, and Greece. This somewhat elongated Jurassic back-arc ocean underwent early compression, “docking” and nappe-stacking in the latest Jurassic–earliest Cretaceous. The Tithonian(Berriasian) limestones, which stratigraphically overlie the Middle Jurassic oceanic crust, are not only crucial markers of the latest Jurassic contraction and exhumation but also bear significant implications for the NeoTethyan Vardar developments (evidence of paleokarstification). During the latest Jurassic–earliest Cretaceous compressional event, the oceanic crust belonging to the EVZ interacted with the Dacia Mega-Unit and its Serbo-Macedonian continental margin. By introducing new structural observations, this study covers the interference character between the EVZ periphery and the western Serbo-Macedonian Unit. Supported by previous mapping results, new structural data are extracted from several key outcrops distributed across central Serbia (Dobroljupci, Kuršumlija, Jastrebac Mt.). The analyses of geodynamic implications related to the NeoTethyan Vardar contraction have outlined the latest Jurassic-earliest Cretaceous accretionary-type deformation embedded in the peripheral units (Tithonian-Berriasian limestones, mélanges, Serbo-Macedonian gneiss). These findings are significant as they provide a deeper understanding of the geological processes that shaped this region during the mid-Mesozoic. Despite Late Alpine overprinting, the latest Jurassic arc-type “soft collision” or “docking” (no evidence of significant crustal thickening with a very limited obduction) produced the newly observed NNE-SW oriented folds. The folds are observed within the Jurassic carbonate rocks and greenschist-facies rocks of likely similar age and origin (train of steeply plunging synforms, D₁). The tectonic resetting and initiation of post-collisional progressive subduction remobilized the stalled remnant of the Vardar marine corridor after the short-term Berriasian exposure and palaeokarstification. Such tectonic developments triggered a foreland-type subsidence and accumulation of the clastic-carbonate Lower Cretaceous “paraflysch” on top of the EVZ ophiolites/mélange/Tithonian limestones. However, the new depositional cycle and the oldest Lower Cretaceous paraflysch sequence remain devoid of ophiolite inclusions.