Paleozoic tectonostratigraphic units of the northwest and central Dinarides and the adjoining South Tisia

Abstract

In the Central Dinarides and South Tisia different Paleozoic complexes occur in four geotectonic zones: (1) comparatively autochthonous units located in the cores of disrupted anticlines of the External Dinarides; (2) allochthonous disrupted units accompanied by more predominant Triassic formations in the Sava Nappe, which is thrust onto the northeastern margin of the External Dinarides; (3) allochthonous disrupted units, also together with Triassic formations, in the Pannonian and Durmitor nappes of the Internal Dinarides; and (4) polymetamorphic sequences in basement of the Pannonian Basin and South Tisia, respectively. This paper presents basic geological features for the main Paleozoic areas included in these four zones. The tectonostratigraphic units of the first two zones were related to the Gondwana passive continental margin, those of the third zone to the Paleotethyan oceanic realm, and those of Tisia to the active Laurussia margin. Geodynamic evolution of all these Paleozoic complexes was related to opening and closure of the Rheic and Paleotethys Oceans. Rifting processes along North Gondwana started in the Silurian, locally in the Cambrian-Ordovician, and were followed by the Late Silurian/Devonian opening of the Paleotethys. Subduction processes were active by the end of the Devonian and at the beginning of the Carboniferous along the Laurussia margin. They were followed during the Westphalian by main Variscan deformation during collision of Gondwana and Laurussia. Associated metamorphism was very low-grade in the Paleozoic units of the Sava Nappe, low-grade to epidote-amphibolite grade within the Paleozoic complexes of the Pannonian and Durmitor nappes in the Internal Dinarides, and polymetamorphic with migmatites and granitoids in South Tisia. These processes gave rise to a Pangea stage with the Variscan basement disconformably overlain by Late Carboniferous and Permian sediments.

Tectonothermal history of the basement rocks within the NW Dinarides: new40 Ar/39 Ar ages and synthesis

“…The main process during the Carboniferous within Variscan Europe was the closure of the Paleotethys due to the progressing collision between Gondwana and Laurussia (e.g. Pamić & Jurković 2002). This process led to the exhumation and surface uplift of medium-grade metamorphic units and subsequent erosion of the Variscan orogen.…”

“…Previous K-Ar ages from Mid-Bosnian Schist Mts show two age groups, namely 159-92 Ma and 50-37 Ma , Schmid et al (1998), Willingshofer (2000 and Tomljenović (2002). (Palinkaš et al 1996;Pamić & Jurković 2002;Pamić et al 2004). Low-grade metamorphic Paleozoic basement rocks of the Medvenica Mts show ductile deformation and an Early Cretaceous metamorphic overprint dated at 122 to 110 Ma (Belak et al 1995a,b;Judik et al 2006).…”

“…The Adriatic Carbonate Platform and its correlatives, together with the East Bosnian-Durmitor Zone constitute the External Dinarides, while the Dinaric Ophiolite nappe and the Sava-Vardar Zone represent units of the Internal Dinarides. Equally, the Internal and External Dinarides contain exposed Paleozoic basement units with various degrees of metamorphism, mainly up to greenschist, in some cases up to epidote-amphibolite facies conditions (for overview see Pamić & Jurković 2002). The Paleozoic basement units are composed of Ordovician to Carboniferous (Permian) meta-sedimentary rocks (dominantly Carboniferous turbiditic flysch sandstones and shales and Permian molasse-type deposits) and meta-volcanics overlain by a mainly Triassic carbonate-clastic cover.…”

“…The Paleozoic basement units of the Dinarides can generally be subdivided, on the basis of their internal deformation and metamorphic state, into: i) lowgrade metamorphosed, and ii) very low-grade metamorphosed units (e.g. Pamić & Jurković 2002 and references therein). Low-grade metamorphosed basement units, such as the DrinaIvanjica, Jadar, Mid-Bosnian Schist Mts, Medvednica Mts reveal widespread Alpine metamorphism (based on K/Ar mineral and whole rock ages ;Milovanović 1984;Belak et al 1995a,b;Palinkaš et al 1996;Pamić et al 2004;Judik et al 2006), whereas very low-grade metamorphosed Paleozoic units of the northwestern Dinarides (Petrova and Trgovska Gora) yielded Variscan ages and an Early Permian overprint ( 40 Ar/ 39 Ar ages; Borojević Šoštarić et al 2009).…”

Eoalpine (Cretaceous) very low- to low-grade metamorphism recorded on the illite-muscovite-rich fraction of metasediments from South Tisia (eastern Mt Papuk, Croatia)

“…Typical Tisia rocks are widespread and can be found in the South Transdanubian ranges (Mecsek, Villány Hills), in the Apuseni Mountains (Bihor, Pădurea Craiuli, Codru-Moma, Higni ) and in the Slavonian Mountains (Psunj, Papuk, Krndija), where some of the best outcrops of the South Tisia igneous and metamorphic rocks occur in Mt Papuk (e.g. Pamić & Jurković 2002;. These rocks, which can provide detailed insight into the geological history of the Tisia Unit form polymetamorphic complexes (Pamić & Lanphere 1991).…”