Evolution of the Adria-Europe plate boundary in the northern Dinarides: From continent-continent collision to back-arc extension

Abstract

The Sava Zone of the northern Dinarides is part of the Cenozoic Adria-Europe plate boundary. Here Late Cretaceous subduction of remnants of Meliata-Vardar oceanic lithosphere led to the formation of a suture, across which upper plate European-derived units of Tisza-Dacia were juxtaposed with Adria-derived units of the Dinarides. Late Cretaceous siliciclastic sediments, deposited on the Adriatic plate, were incorporated into an accretionary wedge that evolved during the initial stages of continent-continent collision. Structurally deeper parts of the exposed accretionary wedge underwent amphibolite-grade metamorphism. Grt-Pl-Ms-Bt thermobarometry and multiphase equilibria indicate temperatures between 550 degrees C and 630 degrees C and pressures between 5 and 7 kbar for this event. Peak metamorphic conditions were reached at around 65 Ma. Relatively slow cooling from peak metamorphic conditions throughout most of the Paleogene was possibly induced by hanging wall erosion in conjunction with southwest directed propagation of thrusting in the Dinarides. Accelerated cooling took place in Miocene times, when the Sava Zone underwent substantial extension that led to the exhumation of the metamorphosed units along a low-angle detachment. Footwall exhumation started under greenschist facies conditions and was associated with top-to-the-north tectonic transport, indicating exhumation from below European plate units. Extension postdates the emplacement of a 27 Ma old granitoid that underwent solid-state deformation under greenschist facies conditions. The (40)Ar/(39)Ar sericite and zircon and apatite fission track ages from the footwall allow bracketing this extensional unroofing between 25 and 14 Ma. This extension is hence linked to Miocene rift-related subsidence in the Pannonian basin, which represents a back-arc basin formed due to subduction roll-back in the Carpathians

The Upper Cretaceous ophiolite of North Kozara – remnants of an anomalous mid-ocean ridge segment of the Neotethys?

“…It is another inselberg of the SVZ, which consists of two tectonic units separated by a northward dipping thrust. This structure was recently re-defined by Ustaszewski et al (2010) as a low-angle detachment recording latest Oligocene/Miocene extensional unroofing of the Prosara inselberg. The lower, southern, unit is slightly or non-metamorphosed whereas the upper, northern, unit consists of various rocks metamorphosed under up to greenschist facies conditions (Šparica & Buzeljko 1984;Jovanović & Magaš 1986).…”

“…VLADICA CVETKOVIĆ 1 realm is constrained by a regional metamorphic overprint at 65 Ma, which was recorded on the Maastrichtian siliciclastic rocks belonging to the deepest parts of the SVZ accretionary wedge (Ustaszewski et al 2010).…”

The Campanian–Maastrichtian foraminiferal biostratigraphy of the basement sediments from the southern Pannonian Basin (Vojvodina, northern Serbia): implications for the continuation of the Eastern Vardar and Sava zones

“…The Sava Zone represents the final suture collision zone between the Tisza and Dacia Megaunit and the Dinarides (Schmid et al 2008;Robertson et al 2009), as the extension of the Periadriatic Zone (Pamić 2002). In its northern part, this zone is usually limited to isolated inselbergs within Cenozoic sediments (Robertson et al 2009), consisting of Upper Cretaceous ophiolites intercalated with pelagic limestones, trench deposits, flysch, magmatic and metamorphic rocks (Ustaszewski et al 2010). …”

Investigation of the Central Adriatic lithosphere structure with the AlpArray-CASE seismic experiment

“…Recent teleseismic tomographic images (Bijwaard and Spakman, 2000;Piromallo and Morelli, 2003;Koulakov et al, 2009) show a shallow high-velocity anomaly beneath the central and the southern Dinarides reaching approximately 200 km of depth. Most interpretations suggest this represents underthrusting of the Adriatic microplate beneath the Dinarides Schmid et al, 2008;Ustaszewski et al, 2010;Handy et al, 2015;Šumanovac, 2015). Moreover, by analysing GPS measurements, Bennett et al (2008) argued for an ongoing subduction process of the Adria lithosphere beneath the central and the southern Dinarides whilst simultaneously proposing a best matching fault plane solution for the large regional earthquakes.…”