Geodynamic evolution of the Central Dinarides

Abstract

The central part of the Dinarides, unlike the northwestern and southeastern Dinarides, shows a consistent pattern in the distribution of the large tectonostratigraphic units. From southwest (Apulia) to northeast, the following five main units originating in different parts of the Mesozoic Tethys, can be distinguished: (1) Adriatic–Dinaridic carbonate platform formations; (2) carbonate–clastic units (`flysch bosniaque') of the passive continental margin; (3) ophiolite-bearing formations of the Dinaridic Ophiolite Zone, also containing radiolarites, greywackes and shales, including mélange formations, and overstepped Late Jurassic to Cretaceous cover sequences; (4) active continental margin units represented by Upper Cretaceous–Palaeogene trench sediments with blueschists, tectonized ophiolite mélange, Alpine medium-pressure metamorphic rocks originated from Upper Cretaceous–Palaeogene sediments, and Alpine synkinematic granitoids; (5) a nappe consisting of allochthonous Palaeozoic–Triassic formations which is thrust onto the ophiolites and genetically related sedimentary formations. The frontal parts of this nappe directly overlie the northeastern margin of the Adriatic–Dinaridic carbonate platform, i.e. the External Dinarides. The evolution of the Central Dinarides was controlled by a sequence of tectonic events which took place within the Alpine cycle: (1) Rifting processes lasting some 40–50 Ma which started in the Late Permian and ended in the Norian. (2) Opening of the oceanic Dinaridic Tethys commenced in the Late Triassic and persisted for some 70–80 Ma until the end of the Jurassic. (3) Subduction processes and emplacement of ophiolites started in Late Jurassic–Early Cretaceous times; during the closing phase of the `Dinaridic Ocean' (or Dinaridic Tethys) the Palaeozoic–Triassic nappe was emplaced on the ophiolites. The thrusting was accompanied by Alpine metamorphism (120–100 Ma). (4) The main Alpine deformational event and medium-pressure metamorphism with synkinematic granite plutonism took place in Late Eocene–Early Oligocene times when the ophiolite and Palaeozoic–Triassic nappes were emplaced on the Adriatic–Dinaridic carbonate platform which, at the same time, was deformed resulting in the development of the External Dinarides fold-and-thrust belt.