Stratigraphy and paleogeographic environments for the forming the Carpian Series (Stryi and Opir River basins, Ukrainian Carpathians)

Abstract

Results of studying the Carpian Series – a component of the thick Lower Cretaceous-Miocene flysch of the Outer (Flysch) Carpathians are presented in the article. Sediments of the Carpian Series (Middle Paleocene – Eocene) were studied in the Skole Beskids in the basin of the middle and lower reaches of the river Opir in the area of conducting geological and geographical educational practices of students of Ukrainian universities. Using the method of sedimentological analysis, it was found that the investigated sediments are the product of the activity of gravitational flows (mainly turbidites, as well as grainites, debrites), bottom currents and background hemipelagic sedimentation. These sediments are compared with the facies of deep-marine fans placed on the continental slope and its foot. Medium- and coarse-grained turbidites and grainites (Yamna and Vyhoda formations) correspond to the submarine valley-channel facies. Fine- and medium-grained turbidites and hemipelagites (Manyava and Bystrytsa formations) belong to the inter-channel facies. The composition of the clastic material (green and red phyllites) suggests, that the sediments were drifted from the Eurasian continental margin into the deep-marine fan (fans?). Applying the micropaleontological method, it was established that the Paleocene-Eocene background red and green clay hemipelagites are enriched in buried in situ benthic foraminifera (deep-water agglutinated foraminifera: DWAF), which indicate lower bathyal – abyssal depths of flysch accumulation below a calcite compensation depth (CCD). Late Eocene calcareous lithofacies of the Popiele Formation contain a mixed foraminifera assemblage formed as a result of mud and debris flows. Shallow-water fauna and “exotic” debris (including the red and green phyllites) were transferred from the shelf area to the deep basin. The Latest Eocene hemipelagic clay-carbonate sediments of the Sheshorian horizon contain the foraminiferal assemblage with plankton dominance, which indicates a general shallowing of the paleobasin (middle-upper bathyal conditions above a calcite compensation depth) at the end of the Carpian time. Key words: stratigraphy, paleogeography, Ukrainian Outer Carpathians, Paleocene-Eocene flysch, turbidites, foraminifera.