Abstract
Biostratigraphic analysis of fossils material has allowed the documentation of sediment gravity flows in the Skole basin during the Paleocene and Eocene times, and also in the Eocene-Oligocene transition. This most external basin of the NE Outer Carpathians was a marginal sea especially sensitive to geotectonic instability and relative sea-level change, favoring the development of down slope movements at these times. The dominance of calcareous forms in foraminifera, and a large share of redeposited species among the nanno- and microfossils indicate a close relationship of sediments containing them with the shelf environment and documents not too long transport. Additionally the recycled forms are often well preserved, indicating that the rock contained in flows were only plasticized and hydrated while the material itself was not a subject of significant mechanical processing in contrast to that one, which directly documented down slope moving. The latter forms are bad preserved and their fossil remains are usually corroded, partially dissolved and broken during this process. In addition, the planktonic forms including foraminifera, calcareous dinocysts and nannoplankton allow documenting the time of the final deposition of the sediment transported on slope.
Highlights
The Outer Carpathians successions in Poland and Ukraine are seen primarily as a wide range of deep water sediments, which were deposited by turbidity currents of different densities
The presented studies concentrate on the foraminifers and calcareous nannoplankton from the deposits reworked by a rapid downslope flow of poorly-sorted debris mixed with water
The sedimentologic nature and the micropaleontological content of the studied deposits from the Paleogene flysch of the Skole unit determine https://journals.agh.edu.pl/geol their origin and age. These deposits were transported down slope by sediment gravity flows of high concentration and accumulated in the Paleocene (Babica clays), Middle Eocene (Czudec clays) and Lower Oligocene (Popiele beds, local mudstones layers in the Menilite-Krosno series) rocks
Summary
The Outer Carpathians successions in Poland and Ukraine are seen primarily as a wide range of deep water sediments, which were deposited by turbidity currents of different densities. The presented studies concentrate on the foraminifers and calcareous nannoplankton from the deposits reworked by a rapid downslope flow of poorly-sorted debris mixed with water (debris flows sensu Johnson & Rodine 1984) Deposits of this type occur in the Paleogene series of the Outer Carpathians in Poland and Ukraine (Dżułyński et al 1959, Dżułyński et al 1979, Ślączka & Kaminski 1989, Kruglov 1989, Rajchel 1990) (Fig. 1). After anoxic episodes in the Early Oligocene, correlated with a drastic sea level fall in the Skole basin, the sedimentation of the sandstones series of large thickness took place (socalled Krosno beds) They were deposited under conditions of increasing subsidence (Haq et al 1988, Kotlarczyk & Uchman 2012). The presented studies carried out on deposits belonging to the Skole unit, which expose in the Dynów Foothills as the Babica clays: Kosina stream in the vicinity of Połomia (Fig. 3A, B) and Czarnotówki localities in Poland, the Przemyśl Foothills as the so-called Czudec clays: Wara (Fig. 3C, D), Połomia and Czarnotówki localities in Poland, and in the front of the Eastern Beskid as the Popiele beds in Poland (Koniusza and Pacław localities) and Ukraine (Trochaniv and Schodnica localities) (Fig. 3E, F)
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