Hydrogeochemical modelling of chloride mineral water from Rabka spa (Carpathian Mountains, Poland)

Abstract

Rabka has resources of chloride water, currently accessible in nine boreholes with depths from 20 to 1215 m. The waters are of the Cl-Na+I+(Fe) type, and in the Rabka IG 2 borehole of the Cl-Na+I+21°C type, while their total dissolved solids (TDS) contents vary between 17.2 and 24.6 g/dm 3 . These therapeutic waters are associated with the Carpathian flysch strata of the strongly disturbed zone of tectonic contact between the Magura Nappe with the underlying Fore-Magura Group of units. This structure is also a trap for hydrocarbons, and so strong methane (CH 4 ) emanations are present in Rabka both at the surface and in the boreholes providing mineral water. The strong tectonic disturbances of the study area considerably hinder the flow of underground water, extend the water resistance time at the water-rock contact and significantly limit the possibility of water exchange within the water-bearing system. Such conditions of hindered flow and limited water exchange control the unique chemical composition of the chloride water at Rabka. The components dissolved in these waters originate from the primary synsedimentary water (elision stage) accumulated in the rock matrix, from which they filter into the flow of water (infiltration stage) of various geneses, i.e., palaeoinfiltration, infiltration and dehydration, moving through the water-bearing system of the mineral water of Rabka. Modelling with the Geochemist’s Workbench Standard 8.0 program has demonstrated the proposed origin of the mineral water in Rabka.