TECTONIC-SEDIMENTARY EVOLUTION OF THE DUKLA NAPPE, UKRAINIAN CARPATHIANS

The knowledge of the stratigraphy, tectonics and evolution of the Dukla Flysch Nappe of the Ukrainian Carpathians has been supplemented on the basis of geomapping works, structural, sedimentological and micropaleontological studies. Four foraminiferal assemblages are distinguished in the studied sediments. The assemblages (1) and (2) containing Deep-Water Agglutinated Foraminifera suggested bathyal-abyssal depths. Assemblages (3) and (4) are characterized by planktonic and calcareous benthic foraminifera. The assemblage (3) indicates bathyal depths, and the assemblage (4) – upper bathyal–littoral depths. The following formations as indicators of the accretionary prism evolution were identified. Pre-orogenic formation of the remnant flysch Carpathian Basin contains the sediments that accumulated between the active margins of the microcontinental terrane and the passive margin of Eurasia. It includes the Cretaceous–Eocene flysch containing foraminiferal assemblages (1) and (2). The pre-orogenic formation contains conglomerates with exotic clasts suggesting the uplifts interpreted as fore-bulges migrated towards foreland. Synorogenic formation is represented by latest Eocene–Oligocene deposits belonging to ‘piggy-back’ and trench-like facies. The ‘Globigerina Marl’ (Eocene/Oligocene transition) contain assemblages (3), and the Oligocene sediments (Turytsa and Dusyno subnappes of the Dukla Nappe) contain assemblages (4). The change from bathyal-abyssal depths to upper bathyal–lower littoral depths, which began at the turn of the Eocene and Oligocene, could be caused by syn-sedimentary tectonic movements. The diachronic ‘younging’ of the trench-like coarse-clastic facies suggests the migration of the trench. Post-orogenic formation was accumulated in the wedge-top basins on the Dukla Nappe. The identified formations indicate the accretionary prism growing.