Exotics-bearing layer in the Oligocene flysch of the Krosno Beds in the Fore-Dukla Zone (Silesian Nappe, Outer Carpathians), Poland

A layer with exotic blocks has been found in the flysch of the Krosno Beds, in the Fore-Dukla Zone (the southernmost part of the Silesian Nappe in the Bieszczady hits, Polish Outer Carpathians). It has been traced over a dist ance of I km near Wetlina (the Bieszczady Mts), in the southernmost exposed tectonic slice. The exotic blocks include crystalline schist (quartz-chlor ite-muscovite-orthoclase schist with tourmaline and garnet) and three types of limestones: 1/ massive, sparitic, partly siliceous limestone, with nume rous calcite veins; 2/ micritic limestone with rare planktic (Globigerina-l ike) foraminiferal tests; 3/ bioclastic limestone with numerous tests of sm all and large foraminifers, coralline algae (Rhodophyta), bivalves, bryozoa ns and rare echinoid spines. The exotics are embedded in light- and dark-gr ey argillaceous, partly sandy, calcareous matrix, together with a few small angular pebbles of grey mudstones and very fine-grained sandstones, which resemble lithological types of the Krosno Beds. The described rocks are sim ilar to those found as exotic blocks in the Krosno Beds in neighbouring are as (Roztoki Dolne and Ustrzyki Gorne) of the Central Carpathian Depression (Silesian Nappe). Calcareous nannoplankton from the exotic-bearing layer an d neighbouring deposits show that they are not older than the NP24 Zone (la te Kiscellian), below the isochronous marker horizon of the Jaslo Limestone . It may correspond to the Tenuitella munda Zone of Olszewska (1997, 1998), proposed for the Polish part of the Central Paratethys. The source area of the layer with exotics (islands with narrow shelf margins), probably lay t o the south and south-east, was built mainly of crystalline rocks, and part ly covered by various types of carbonate Eocene-Oligocene rocks. The deeper parts of the island slopes were covered with Cretaceous-Paleogene sediment s, related to deep-water sedimentation in the marginal zone between the Duk la and Silesian subbasins. These deep-water deposits have been partly erode d during the submarine mass movements descending to the Silesian Subbasin.