Genesis of the brines in the south-eastern part of the Danube Basin, Slovakia

Authors: Franko O., Pereszlenyi M., Bodis D.
Journal: Mineralia Slovaca
Issue: 43/4/2011
Language: Slovak (Abstract in English)
Info: Article PDF (1.77 MB)
Link: Mineralia Slovaca

Abstract:
In the south-eastern part of the Danube Basin the brines with TDS greater than 35 g.l-1 occur. The evolution of the chemical composition of brines depends not on the age of aquifers, but on the water source, sources of salinity and the conditions at different stages of evolution. The origin of the brines is analyzed by interpreting the information of geological and tectonic conditions, paleogeographic evolution of the Neogene and of paleohydrogeological reconstruction. These data represented the basis for the interpretation of results through the inverse modeling with code PHREEQC. The result of modeling at 5% uncertainty for all ions showed that autochtonous seawater in the ration 4.73:1. In further evolution they have been affected by metamorphism including the processes of ion exchange, calcite dissolution and precipitation of gypsum, dolomite and halite. Together with the reduction of sulphate to H2S and CO2 interaction, the final chemical composition of the brine was created. Allochtonous brines, for example of GTM-1 borehole Marcelová, were according to the results of inverse modeling in the first stage pre-concentrated by evaporation of seawater in a ratio of 3.19:1. Evaporation could begin during the Badenian, or Sarmatian. Then the concentrated waters re-migrated to the Lower Triassic aquifers, where they were further formed by the water – rock interactions. Dominant processes in this phase were the dissolution of calcite, dolomite, strontianite and precipitation of halite. At present, both types of brines are located in hydrogeological and hydrogeochemical closed structures.

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