Geneza mis jeziornych Pojezierza Łęczyńsko-Włodawskiego: hipotezy a rzeczywistość rozwoju krasu węglanowego
Abstract
The origin of lake basins in the Łęczna-Włodawa Lakeland: hypotheses and reality of carbonate karst development.
A b s t r a c t: The article concerns the controversy on the four hypotheses of karst origin of lake basins in Upper Cretaceous carbonates of the Łęczna-Włodawa Lakeland (central-eastern Poland; Fig. 1). The hypotheses assume that the lake basins (Fig. 2) developed in the Holocene with the active morphogenetic participation of subartesian waters. The main problem is the lack of references to the laws of thermochemistry and kinetics of dissolution of carbonate rocks. In the Ca2+ and HCO3 concentrations in the medium solution (Tab. 1), rationally adopted for this work, the values of the enthalpy, entropy and Gibbs potential/free energy have been calculated (formulas: 9, 10 and 11). Using the conductometric method (Tab. 2, Figs. 3 and 4), the kinetics of dissolution of carbonate basement rocks, i.e. reaction rate v (formula 13), rate constant k (14a), and reaction half-life t1/2 (15), have also been determined. These investigations show that the theses formulated in the hypotheses are not acceptable. The rationale for such an assessment is the incompatibility of the assumptions of the hypotheses with the first and second law of thermochemistry. The second important reason is the ignoring of chemical kinetics as an indirect indicator of the time of the formation of the karst features. According to the author, the main period of the formation of lake basins, in terms of their origin, should be associated with palaeokarst of Neogene deposits.
A b s t r a c t: The article concerns the controversy on the four hypotheses of karst origin of lake basins in Upper Cretaceous carbonates of the Łęczna-Włodawa Lakeland (central-eastern Poland; Fig. 1). The hypotheses assume that the lake basins (Fig. 2) developed in the Holocene with the active morphogenetic participation of subartesian waters. The main problem is the lack of references to the laws of thermochemistry and kinetics of dissolution of carbonate rocks. In the Ca2+ and HCO3 concentrations in the medium solution (Tab. 1), rationally adopted for this work, the values of the enthalpy, entropy and Gibbs potential/free energy have been calculated (formulas: 9, 10 and 11). Using the conductometric method (Tab. 2, Figs. 3 and 4), the kinetics of dissolution of carbonate basement rocks, i.e. reaction rate v (formula 13), rate constant k (14a), and reaction half-life t1/2 (15), have also been determined. These investigations show that the theses formulated in the hypotheses are not acceptable. The rationale for such an assessment is the incompatibility of the assumptions of the hypotheses with the first and second law of thermochemistry. The second important reason is the ignoring of chemical kinetics as an indirect indicator of the time of the formation of the karst features. According to the author, the main period of the formation of lake basins, in terms of their origin, should be associated with palaeokarst of Neogene deposits.