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Geneza mis jeziornych Pojezierza Łęczyńsko-Włodawskiego : hipotezy a rzeczywistość rozwoju krasu węglanowego

Janiec B.

Przegląd Geologiczny

2014

Vol. 62, nr 5

257--266

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.

Iły krakowieckie jako wskaźnik litostratygrafii w dolinie rzeki Sopot na Roztoczu

Janiec B., Czarnecka B.

Przegląd Geologiczny

2006

Vol. 54, nr 10

913-918

The results of micropaleonthological studies of the Sarmatian (upper Miocene) Krakowiec Clays from primary deposit as well as re-deposited ones were applied to the analysis of the stratigraphic profile of the Sopot valley fills. The study site was at the break section of the Sopot River valley in a contact zone of southern escarpment between the central part of the Roztocze and Sandomierz Basin regions (SE Poland). Species of fossil microfauna (foraminiferans, radiolarians), sponges and mollusks, as well as residual deposits were used. The documented, even if apparently small change in the lithostatigraphic profile of the Sopot valley fills, i.e., the presence of pre-Pleistocene deposits in its floor, is very important for the valley history and for interpreting other problems of river breaks and the Roztocze escarpment zone itself, e.g., sclae of the Holocene movements elevating the Roztocze Region, and their effect on expected intensity of deep fluvial erosion. In the sub-scarp zone of the Tomaszów Roztocze subregion the Krakowiec Clays occur rather shallowly. In the Sopot valley (‘Czartowe Pole’landscape preserve) they are in contact with calcareous formations. In two levels of natural clays’exposures, a dozen or so foraminiferan taxa were found. They were also below the primary deposit on the floor levels of the Sopot valley fills. The residuum of the studied strata consists of glauconite and pre-Pleistocene quartz sands, without silicate and alumosilicate, typical for postglacial formations. The Sarmatian clays present in residue were redeposited at least in the pre-Pleistocene. From the clays top up to the surface of valley fills, are Holocene deposits. The study revealed that: (1) during the Holocene and earlier the Sopot valley fills were not removed completely; (2) the floor of the valley is made not of the youngest, Holocene strata, but much older; (3) the presence of the Sarmatian microfauna in the alluvia allows to date the studied deposits as pre-Pleistocene (Pliocene?); (4) fine quartz sands and glauconite (a specific form of hydromica) both forming the residuum of the studied valley fill levels, together with the absence of other silicates and alumosilicates that are common in the Pleistocene formations, exclude the studied Krakowiec Clays from the group of glacial or fluvioglacial (Pleistocene) formations; (5) the youngest (latest Pleistocene –Holocene) movements elevating the Roztocze Region and the resulting deep fluvial erosion do not correspond with shallow occurrence of the pre-Pleistocene valley fills; this requires further discussion.