Złoże soli kamiennej w Łężkowicach nad Rabą

Aleksander Garlicki




Exploration works carried on by the Geological Institute from 1956 to 1960 led to a discovery of a new Miocene salt deposit Łężkowice-Siedlec. After documentation exploitation began in 1968 within the western part of this deposit at Łężkowice salt was exploited by leaching it with water through bore holes made on the surface.
Ample core materials of these drillings allowed the author to make a detailed lithological description of the rocks in the deposit examined, and to draw detailed geological cross section.
Generally, folded Miocene formation overthrust northwards, disclosing the salt deposit here considered, and autochthonous Miocene farmations may be distinguished in the vicinity of Łężkowice (Fig. 2). The two tectonic units are separated with an oblique overthrust plane. Tectonic phenomena that led to the formation of the salt deposit in the overthrust unit may be presented in several development phases (Fig. 3). In the sediments of the evaporate series that makes here the salt deposit, characteristic key members have been distinguished, and a normal section of these sediments has been reconstructed (Fig. 4). The thickness of the sediments amounts to approximately 100 m.
The intrinsic tectonics of the deposit (Fig. 5 and 6) reveals some main elements:

1 – resistance threshold built up of the clayey Chodenice Beds, found north of the deposit; 2 – folded deposits of the evaporate series in the lower and middle parts of the deposit, 3 – the uppermost tectonic element overthrust on the upper part of the deposit, 4 – Sub-evaporate Beds slightly folded under the deposit, and steeply dipping in is southern part. The salt layers in the deposit underwent a strong plastic deformation, whereas the cay-anhydrite sediments were disrupted and squeezed out.
The area of the salt deposit at Łężkowice amounts to approximately 0,5 km2, salt reserves being about 100 mill. tons. The width of the depositional zone ranges from 400 to 700 m, and the greatest depth of salt occurrence does not exceed 450 m. NaCl content, taken as an average for the whole deposit, amounts to 81%. The remaining 19% fall to the substances insoluble in water, and to CaSO4. In some samples also potassium content has been determined, which does not exceed, however, 0,02%.

Full Text: