The Neoproterozoic-Paleozoic basement in the Alpidic Supragetic/Kučaj units of eastern Serbia: A continuation of the Rheic Ocean?

Abstract

This paper attempts to allocate a segment of the Paleozoic Ocean situated in what is now Southeastern Europe (SEE) into a regional geological and paleotectonic synthesis connecting the sedimentary, metamorphic and igneous records associated with the ocean's cycle. The Supragetic basement (external section of the Carpatho-Balkan arch) represents a tectonically reworked basement vestige of the Neoproterozoic-Lower Paleozoic oceanic floor system recrystallized under regional low temperature greenschist-facies conditions. The regional geological constraints associated with this low-grade basement are integrated with information from the overlying Silurian, Devonian and Lower Carboniferous cap-rocks of the "Kucaj Unit" to demonstrate the presence of a major Paleozoic ocean crossing this segment of SEE. In connection with the Lower Paleozoic north Gondwanan Pan- African processes, the low-grade Supragetic basement (including its Devonian cover) is in a complex relationship with the occasionally anchimetamorphic Silurian, Devonian, and Lower Carboniferous deep-water record of the polymetamorphic "Kucaj Unit". The Upper Devonian-Lower Carboniferous flysch and molasse of the "Kucaj Unit" are interposed with the Neoproterozic-Lower Paleozoic oceanic vestige or with the Supragetic basement with the corresponding Devonian Balkan-Carpathian back-arc ophiolite-bearing lithosphere and its carrier (Danubian Unit). This regional-scale synthesis demonstrates that a segment of the Rheic Ocean referred to as the Saxo-Thuringian seaway and its suture lay to the east, underneath the Permian red-bed overstepping sequence and to the west of the Danubian aggregation. Unlike many of the high-pressure rocks characterizing the segment of the Rheic suture in the Central European Variscides, the SEE zone described here has only a mild overprint.