Środkowy trias na obszarze zapadliska przedkarpackiego

Abstract

THE MIDDLE TRIAS ON THE AREA OF THE PRE-CARPATHIAN DEPRESSION

The author discusses thelitho10gical development and the stratigraphy of the Lower and Middle Trias upon the area situated south and southeast of the Święty Krzyż Mountains. Both a correlation of bore-hole sections and the stratigraphy are Illustrated on Table 1.

On the basis of considerations on the sedimentation of the Lower and Middle Trias the author concludes that during the Zechstein the discussed area has only partIy been submerged by the sea. During the Bunter, on the other hand, this entire area has already been subject to a sedimentation which was taking place in relic post-Zechstein basins; simultaneously there went forth a partial subsidence of the areas which during the Zechstein were land. Here the Bunter deposits were laid down on Carbonaceous beds.

In the lower part of the Middle Trias the sea transgressed from the south through the Moravian Gap. The author surmises that a similar connection with the sea may have existed along the eastern margin of the Ancient Carpathians; however, investigations of bore-holes sunk there tailed to supply palaeontological evidence collaborating this conjecture.

The stopping up of the connection byway of the Moravian Gap and of the probable connection in the eastern part of the Ancient Carpathians occurred simultaneously, at the boundary between the Lower and Middle Muschelkalk; this event is clearly. indicated by the lithological character of those sediments. The Upper Muschelkalk is featured by a renewed development of fauna, whereas the sediments show that during the entire Upper Muschelkalk a marine sedimentation went forth here. The transition from Muschelkalk to Keuper is marked by a sharp boundary, since immediately on top of the limestones there starts the sedimentation of "Lettenkohle" beds of the Lower Keuper.