Profil kredy dolnej z Bełwina w Karpatach przemyskich

Abstract

PROFILE OF THE LOWER CRETAOEOUS FROM BEŁWIN IN THE PRZEMYŚL CARPATHIANSIn the northern marginal zone of the Przemyśl Carpathians, in the vicinity of Bełwin, there emerges from under the inoceramian beds of the Skole unit a series, of sediments lithologically resembling those of the Lower Cretaceous, described by B. Kokoszyńska (1949) from the vicinity of Dobromil.The Lower Cretaceous sediments form here an upright fold of NS trend, cracked in its exial part and slightly inclined to the east. In the western, raised flank of the fold the oldest strata occur, comprising marly siltstones with macro-fauna and lower Spas shales, whereas in the eastern flank series of strata is persisted, ranging from the upper Spas shales to the siliceous marls. Oldest in the Lower Cretaceous diapire fold, discussed here, are marly siltstones, for which the name "Bełwin siltstones" is introduced. On microfauna, their age has been established to be Hauterivian. Higher, there occur the lower Spas shales. These are black·shales, partly argillaceous, partly marly, with interbeddings of thin-layered sandstones. These latter represent 1% of the entire sediment. In tile lower part of the lower Spas shales the main horizon with spherosiderites was encountered; the microfauna of these beds indicates their Barremian age. In the upper Spas shales, in turn; there occur flint shales, brown and black in the lower part, and ashen-grey and black in the upper part. They are terminated by a horizon of manganese-bearing shales. Their age is assumed to be from Aptian to the Lower Cenomanian.Green shales with radiolaria constitute the upper member of the profile under discussion. In this member red shales are lacking. On the basis of a correlative horizon of the manganese-bearing shales and a horizon of shales with radiolarian the age of the green shales was determined to be Cenomanian. In the upper part of the green shales interbeddings of silicified marls appear, which form, in the uppermost parts, a compact complex of siliceous marls, probably already representing the Turonian.