The East-Carpathian Crystalline-Mesozoic Zone (Romania): Paleozoic Amalgamation of Gondwana- and East European Craton-derived Terranes

The Alpine orogen of the Eastern Carpathians contains pre-Alpine terranes framed by younger rocks. The geological data on these terranes are reviewed and interpreted in order to elucidate their geodynamic evolution during the Paleozoic. The Rebra-Tulghes terrane shows a stratigraphic sequence similar to Avalonia: Neoproterozoic platformal metasediments (Rebra Group) overlain by late Neoproterozoic volcano-sedimentary rocks (Pietrosu Bistritei porphyroids) and Lower Paleozoic cover (Tulghes Group). The Bretila terrane, made up of orthogneisses, pelitic gneisses, granites, amphibolites and micaschists, shows affinities with the basement of the East European Craton. The modern juxtaposition of the Bretila terrane and the Rebra-Tulghes terrane may be explained in terms of collision between the latter and the East European Craton during the Ordovician times. As an effect of collision, the Bretila terrane was thrust over the Rebra-Tulghes terrane and induced the occurrence of thrust faults within it. A Lower Paleozoic emplacement of the East-Carpathian pre-Alpine thrust nappes is thus inferred.