Uwagi o rozwoju rowu Kleszczowa na tle wybranych elementów paleohydrogeologii regionu

Tomasz Michalski

Abstrakt


SOME REMARKS ON THE DEVELOPMENT OF THE KLESZCZÓW TROUGH AT THE BACKGROUND OF SELECTED PALEOHYDROGEOLOGICAL FEATURES OF ITS AREA

Summary
The analysis of paleohydrogeological conditions in the Kleszczów trough area made it possible to put forward a hypothesis of development of the trough at the background of reasons and results of groundwater movement, forced by various agents and independent of location of recharge zones. This hypothesis is based on the assumption that groundwaters were reacting to changes of stress conditions in the Earth crust by increase or decrease of pressures responsible for their movement.
The above mentioned stresses were originating in result of overthrusting of the Carpathians, vertical movements of the Earth crust in area of the Kleszczów trough, icesheet load varying in time, and origin and disappearance of permafrost. Movement of waters was taking place in all the aquifer systems, in accordance with stratification. Fault zones acted as the priviledged zones of drainage here. Waters moving upwards by these zones were dissolving chlorine, sulfate and carbonate rocks, the total thickness of which in the Permo-Mesozoic cover in this region equals about 1,500 m. The processes of dissolving were here facilitated by the presence of salts of chloric and sulfuric acids: NaCl, Na2SO4 and others. The studied region is situated in southern, peripheral part of the area of distribution of the Zechstein salinary formation. Moreover, CO2 and H2S occurring in gas found in Mesozoic rocks, make the waters strongly aggressive. All these factors were facilitating intense development of karst phenomena at various depths. Prolonged action of intense shearing movements on top parts of karst forms, leading to their collapse and accompanying origin of faults and structures resembling tectonic troughs.
The collapse of roof parts of karst forms was also due to loading by icesheet. The resulting depressions became subsequently infilled with ice and ice-transported material. After shearing-off the ice at the terrain surface level, a new ice with transported moraine material appeared above dead ice blocks. Collapse of deeper and deeper seated karst forms was followed by deposition of a few till horizons of the same age in the trough. It follows that subsidence of floor in the Kleszczów trough was due to both tectonic factors and prolonged, forced movement of groundwaters, independetly of the effects of their flow, determined by location of recharge- discharge zones.

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