Kras w osadach tortonu okolic Piaseczna koło Tarnobrzega

Abstract

KARST FEATURES IN THE TORTONIAN SEDIMENTS OF THE PIASECZNO AREA NEAR TARNOBRZEGSummaryKarst phenomena developed in the native sulphur deposits at Piaseczno near Tarnobrzeg have been studied to define more precisely their character and age.The secondary karstic processes acting within the deposit obliterate its original features and character (Fig. 1). They are responsible for a decrease in sulphur grade or even a complete deterioration of the deposit in some areas, while others are considerably enriched in sulphur.Hihgly mineralized Tertiary relict waters played a substantial role in the development of karstic processes. According to the present author the mixing of waters of different mineralization degree – in this case Tertiary relict water and surface water – is another factor significant for karst development. It is the mixing effect that entailed the intensification of karst processes. Studying the evolution of the region the present author concluded that at least two periods existed when a considerable interchange between ground and surface waters occurred. The earlier period was related to the formation of depressions in the top surface of the Tertiary sediments filled with pelitic-sandy material, the later to the Baltic glaciation when the Vistula river valley was cut west of the Tarnobrzeg erosional remnant.Among others, karstic activity (Fig. 2) produced breccia ores previously regarded as a metasomatic product of brecciated gypsum. A considerable amount of karstic migration channels, caverns, and voids is now filled with overburden material (pecten clays – Figs. 3 and 6). Their bottom often covered with dark clays, probably karstic residuum (Figs. 4 and 5). In the zone of intensive karst development considerable amounts of desintegrated limestone are found (Figs. 3, 4, 5). In the neighbourhood of zones strongly affected by karst processes they are frequently related to the action of waters that dissolved the limestones.Following the disturbances of the overburden of the sulphur deposit the author establishes the development trend of the karstic migration channels and the extent of the processes.