Tectonic-sedimentary evolution of the southwestern part of the Ukrainian flysch Carpathians

Authors:

O.M. Hnylko, Cand. Sci. (Geol.), Senior Research Scientist, Institute of Geology and Geochemistry of Combustible Minerals under National Academy of Sciences of Ukraine, Senior Research Scientist, Lviv, Ukraine

S.R. Hnylko, Institute of Geology and Geochemistry of Combustible Minerals under National Academy of Sciences of Ukraine, Engineer, Lviv, Ukraine

L.V. Heneralova, Cand. Sci. (Geol.), Associate Professor, Ivan Franko Lviv National University, Senior Lecturer, Lviv, Ukraine

Abstract:

Purpose. Reconstruction of tectonic and sedimentary development south-western part of the Ukrainian Flysch Carpathians.

Methodology. Natural Cretaceous-Paleogene sections of flysch were investigated using the facial method, in particular the sedimentological and micropaleontological analysis.

Findings. There in deposits of the Monastyrets, Magura and Dukla nappes of the Ukrainian Carpathians were identified (for most lithostratigraphic units for the first time), the characteristic texture and structural features indicating these deposits as lithified products of turbidite-, grain- and debris-flows and bottom currents and background hemipelagic settling. It was established that the distribution of associations of small foraminifera in stratigraphic succession of the Dukla Nappe indicates a change of paleobathymetric conditions from lower bathyal-abyssal, with a predominance of agglutinating benthos (Cretaceous, Paleocene and Eocene) to bathyal above foraminiferal lysocline with a predominance of plankton (Upper Eocene), and to the upper sublittoral-bathyal with plankton and varied calcareous benthos (Oligocene). The Monastyrets, Magura and Dukla tectonic units are characterized by a number of features (in particular, "younging" of deposits from internal to external (sub)nappes, confinement of coarse and shallower facies to the upper part of stratigraphic successions) suggest to consider these units as an ancient accretionary prism, which was synsedimentary increased by new thrust sheets during Eocene-Oligocene time.

Originality. Sedimentary processes and environment of deposits of the Monastyrets, Magura and Dukla nappes were reconstructed. Model of involving these deposits into the accretionary prism was proposed.

Practical value. A more detailed and advanced application of sedimentological and microfaunistic analysis, as well as the compilation of historical evolutionary models, will allow forecasting space-age distribution of lithofacies, particularly sandy and clay layers, which is necessary for searches of minerals.

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