Coal-bearing submarine slump sediments from Oligocene–Miocene transition of the Eastern Carpathians (Bieszczady Mountains, SE Poland)

A new finding of lustrous coal particles from the youngest flysch sediments of the Silesian Nappe, Polish Eastern Carpathians, outcropped in the Bieszczady Mountains is here presented. The coal material occurs in a 1-m thick submarine slump layer in the Kiczera Dydiowska Sandstones, which belong to the youngest part of the Krosno Beds. Coal particles are numerous (up to 16%) in a massive sandstone of the slump layer. The siliciclastic particles from these sediments are classified as material from weathered rocks of continental block or they have been recycled from post-orogenic sediments. Lustrous coal represents coaly plant fragments, which are mostly homogeneous, belonging to macerals of vitrinite group. Some coal pebbles display tree structure, typical of gelified xylites, due to impregnation of cell walls by resinite, which occurrence in this material indicates terrestrial plants producing waxes and resins. Some of gelified plant debris shows evidence of pyritization, what in the absence of inertinite macerals in coal may indicate dysoxic conditions during first decomposition processes of organic matter under water environment. Coaly-bearing slump moved down most probably from SW during Oligocene–Miocene transition time. This shows that an intrabasinal massif, as the uplifted fragment of ?Precambrian craton, which supplied large amount of siliciclastic material to the Silesian–Subsilesian basin during the lower–middle Oligocene, still existed at the end of the Oligocene.