GEOLOGICA CARPATHICA, DECEMBER 2020, 71, 6, 526–538 https://doi.org/10.31577/GeolCarp.71.6.4 Geodynamic interpretation of the Late Cretaceous syn-depositional magmatism in central Serbia: Inferences from biostratigraphic and petrographical investigations MARINKO TOLJIĆ1, , BOJAN GLAVAŠ-TRBIĆ2, UROŠ STOJADINOVIĆ1, NEMANJA KRSTEKANIĆ1, 3 and DANICA SREĆKOVIĆ-BATOĆANIN1 1University of Belgrade, Faculty of Mining and Geology, Djušina 7, 11000 Belgrade, Serbia; [email protected], [email protected], [email protected], [email protected] 2Geological Survey of Serbia, Rovinjska 12, Belgrade, Serbia; [email protected] 3Utrecht University, Faculty of Geosciences, Princetonlaan 4, 3584CD Utrecht, The Netherlands; [email protected] (Manuscript received April 3, 2020; accepted in revised form October 28, 2020; Associate Editor: Igor Broska) Abstract: High-resolution biostratigraphic dating of (hemi)pelagic limestones stratigraphically adjacent to syn-depositional bimodal magmatites in central Serbia, based on planktonic foraminiferal assemblages, determines that the magmatism occurred during Coniacian to Santonian. This bimodal magmatism, which includes both basaltic magmas with associated peperites and trachydacitic magmas, was associated with syn-subductional extension, which was triggered by roll-back and steepening of subducting Neotethys oceanic lithosphere, located between the converging continental margins of Adria and Europe. The Late Cretaceous extension led to subsidence and formation of a fore-arc basin above the sub- duction zone. Co-genetic magmatic occurrences, including basalts, trachydacites, and lamprophyres, are distributed in the same fore-arc domain along the entire European continental margin. The fore-arc magmatism migrates in space and time from the south towards the north and north-west. Keywords: syn-subductional extension, bimodal magmatism, biostratigraphy, fore-arc basin, central Serbia. Introduction infill of the fore-arc basin was associated with syn-deposi- tional bimodal magmatism (Toljić 2006; Toljić et al. 2018). Evolution of fore-arc basins, due to their unique position However, the ages of extension and associated magmatism are above the subduction zones, is directly controlled by subduc- still not fully constrained. In this study, we use high-resolution tion-related processes. These processes induce different types biostratigraphy based on planktonic foraminifera combined of sedimentation, variable deformation styles, and also control with petrographical observations to study the geodynamic features and intensity of associated magmatism (Reagan et evolution of a fossil fore-arc system, situated along the active al. 2010; Noda 2016). Subduction-induced magmatism in European continental margin in central Serbia. the upper plate of a subduction system is manifested in the island arc, and fore- and back-arc basins (Stern et al. 2014; Gallhofer et al. 2015). Although an active subduction system, Geological setting of the fore-arc basin as an area of convergence, is generally exposed to compres- in the active European margin sion, extensional strain can exist in the fore-arc, island arc, or the back-arc, as a result of a retreat of the subducting slab The present-day complex architecture of the Adria–Europe (Jolivet et al. 2013; Andrić et al. 2018). The ongoing subduc- suture (Fig. 1) is the result of Mesozoic evolution in the nor- tion is often followed by slab rollback (Jolivet et al. 2013). thern branch of Neotethys Ocean (i.e. Meliata–Maliac–Vardar This is followed by plate decoupling, extension, and magma- Ocean of Schmid et al. 2020; or Vardar Ocean of Dimitrijević tism that often affects the upper plate (Acocella 2014; Bettina 1997). The effects of tectono-depositional evolution of the Neo- et al. 2014). tethys Ocean and the adjoining Adriatic and European conti- A Cretaceous closure of the northern branch of Neotethys nental margins can be recognized in three major tectonic units Ocean resulted in formation of the Sava suture zone between characterized by contrasting lithostratigraphic and structural Adriatic- and European-derived continental units (Pamić features. Going from the west towards the east there are: 2002; Karamata 2006; Schmid et al. 2020). The interplay (i) Jadar–Kopaonik Unit of the Adriatic passive margin with between ongoing convergence and roll-back of the subducting obducted Western Vardar ophiolites; (ii) Sava suture zone and slab controlled geodynamic evolution of basins formed on and (iii) the European margin with obducted Eastern Vardar ophio- near the Adriatic passive margin, trench and the fore-arc basin lites (Fig. 1b, Dimitrijević 1997; Schmid et al. 2020). These on the active European margin (Toljić et al. 2018). Sedimentary three tectonic units represent three different domains in which www.geologicacarpathica.com LATE CRETACEOUS SYN-DEPOSITIONAL MAGMATISM IN CENTRAL SERBIA 527 in e th in s nit ) allochthons u region Peninsula mega-unit n s Danubian, West Balkan, Struma Kula, Forebalkan Getic Carpathian foreland basin Moesia Circum-Rhodope Biharia, Supragetic, Serbo-Macedonian Bihor nappe system Mecsek nappe system Codru nappe system Rhodope upper unit mega-unit Balkan e hodope Eurasian plate Europe-derived th R Europe-derived Pannonia (Tisza s in & w d allochthons allochthons an s phiolites Ceahlau-Severin suture zone Sava suture zone Western Vardar Western ophiolitic unit Eastern Vardar ophiolitic unit d o Bükk, Jadar-Kopaonik Drina–Ivanjica, Korab, upper Pelagonian, East Bosnian-Durmitor, lower Pelagonian Pre-Karst unit, Bosnian flysch High Karst & Parnass units Budva-Cukali, Krasta, Pindos zones Dalmatian, Kruja, Gavrovo-Tripolitza South Alpine unit one ALCAPA lps z inarides Hellenide eA th e D Adria-derived in th Adria-derived 2. Požeška Gora (Pamić Šparica 1983) 3. Southern part of Panonian basin (Dunčić et al. 2017) 4. Resnik (this study) 5. Rušanj (Toljić et al. 2018) 6. Ripanj (Sokol et al. 2020) 7. - Karađorđeva Topola Česma (this study) 8. - Limovac (this study) Topola 9. Klepa (Prelević et al. 2017) Magmatites Location: 1. Kozara (Ustasze ski et al. 2009) Suture Obducte 9. Skopje L. Prespes 8. 7. 6. Priština 5. Topola 4. L. Ohrid Fig. 2 o o o 43 30 o 45 o 47 30 Fig. 3 3. Beograd s s Elbasani ns n o Tirana a an o 26 Gora Adria-derived Europe derived k ka a a t Fruška ia i lk l o 26 st s ni n e es al a re r a an 49 n n ar a i in v va L. Skoder s B Ba h ha l lv Danube si s o ch c nns y yl uc u as a sy ana s B B Bu 51 iia B B Ba ns n ia iaa fi hhi f a tth an of o ra r S ata S So T Tr Kotor rrppap o o ara 22 22 CCa n n t t a an st s ia i es e lavonia e e n n pe p ni n i in de d ap a a ad S da r d ra si s on o a Dubrovnik g gr ud u lg l as a no n B Bu B el e o B Be B b b b nn n o B B Ba 18 Se 1 1 1 an a o s 18 Sarajevo . ees P P Pa g g g 51 ded Gora i i i idi b b Mostar 2. rri e eb Požeška F F Motajica L. Balaton L. L. Balaton L. r re aar gr g 200km nan a ag ini Wien Z Z Za DDi o 42 o 1. 14 0 o Adriatic h 14 Kozara Gora c ch ic i ni n u un M M Mu s s Banja Luka Prosara p ps o Split lp l Europe sensu largo and foredeep Adria 10 A Al o o no n o Zagreb AlpineTethys Miocene thrust belt a an — Tectonic map of the Alps–Carpathians–Dinarides system with the main tectonic units (modified after Schmid et al. 2008). The grey rectangle indicates the location of Fig. 1b. Tectonic Tectonic of Fig. 1b. location indicates the grey rectangle The 2008). Schmid et al. after units (modified main tectonic Alps–Carpathians–Dinarides system with the map of the Tectonic — l la i il 10 o M M Mi o 49 o 47 b) a) 45 Fig. 1. a Fig. suture. Adria-Europe along the triangles) (orange magmatites of shows locations The map 2020). et al. Schmid (after Serbia in central units Adria-derived and Europe- between area contact of the map The black arrows and rectangles indicate the locations of Figs. 2 3. GEOLOGICA CARPATHICA, 2020, 71, 6, 526–538 528 TOLJIĆ, GLAVAŠ-TRBIĆ, STOJADINOVIĆ, KRSTEKANIĆ and SREĆKOVIĆ-BATOĆANIN their Cretaceous sedimentary covers were deposited. From the south-east (Fig. 1b). These magmatites were previously west to east, these domains are basin(s) of the Adriatic passive interpreted as a part of the Vardar Zone (Dimitrijević 1997; margin, subduction trench, and fore-arc basin of the European Karamata et al. 1999), Sava suture zone (e.g Ustaszewski et al. active margin (Toljić et al. 2018). 2009; Prelević et al. 2017), or as a result of magmatism in Cretaceous sediments of the Adriatic margin, located west the fore-arc basin of the active European margin (Toljić et al. from the study area, record Albian–Cenomanian transgression 2018). The westernmost occurrence of such bimodal magma- and Late Cretaceous subsidence that resulted in a gradual tites, reported from the Kozara Mts. (1 in Fig. 1b), consists of deepening of the sedimentary facies (Toljić et al. 2018). Upper Cretaceous isotropic gabbros, doleritic dikes, basaltic In the Belgrade area the trench basin infill, located in the foot- pillow lavas, and rhyolites incorporated in the regional thrust wall of the basal thrust of the Eastern Vardar ophiolitic unit system at the south-western edge of the Sava suture zone in (i.e. the Bela Reka Fault), is Upper Cretaceous deep water the vicinity of the Adriatic passive margin.