| Title | Delineation of Geothermal Aquifers by Magnetotelluric Methods in Besenova – Lucky Area, Northern Slovakia |
|---|---|
| Authors | Marian FENDEK, Slavomir DANIEL, Tomas GRAND, Vincent KULTAN |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | geothermal aquifer, mineral water, magnetotelluric measurements, geophysical and geological profiles, Liptov basin |
| Abstract | Two hydrogeothermal structures are located close to each other in the Liptov basin (northern part of Slovakia). Structure of geothermal waters in Besenova and structure of mineral waters in Lucky are classified as open structures with infiltration, transition-accumulation and outflow areas. Geothermal wells ZGL-1, FGTB-1 and FBe-1 in Besenova showed that geothermal waters accumulate in Triassic carbonates of the Choc and Krizna nappes. It is supposed that formation of geothermal water goes on in Krizna nappe carbonates. Mineral waters in Lucky are also bound to Triassic carbonates of the Krizna nappe. This was proved by results of wells HGL-2 in Kalameny, BJ-101 and HGL-3 in Lucky. No geological investigation was done in this area up to present to confirm or disprove the interconnection between both structures, which water is intensely utilized. The goal of the research was to delineate the relief of the pre-Palaeogene surface, to segment it into lithostratigraphic units and to confirm or disprove the interconnection between Besenova and Lucky water bearing structures. Controlled source audio-frequency magnetotellurics (CSAMT) was the main method used. This method belongs to frequency domain electromagnetic methods. Use of the method supposes resistance contrast in the rock environment, mapping conductivity in relatively wide range. Effective depth reached during the investigation was 2 000 m. This depth was satisfactorily because of the depth of ZGL-1 Besenova well (1 987 m) used for parametric measurements together with the HGL-3 Kalameny well. Altogether 21 CSAMT points were measured. This was the first utilization of the CSAMT method in geothermal research in Slovakia. The results were interpreted in the form of resistance profile, interpreted geophysical and finally geological profile. The results showed that the Pre-Palaeogene basement has a broken, tectonically disrupted relief. Both structures are isolated by Palaeogene sediments (claystone and siltstone) and in the deeper part also by silty carbonates and siltstones of the Jurassic age belonging to the Krizna nappe. It was proven that the continual interconnection of geothermal aquifers in the area between the Besenova and Kalameny-Lucky does not exist. Therefore the mutual influencing of exploited geothermal water in Besenova and mineral water in Lucky was not proven yet, despite of more than 25 years of intense exploitation of geothermal water in both localities. |