Charakterystyka litologiczna mioceńskich osadów chemicznych w widłach Wisły i Sanu

Bolesław Kubica

Abstract


LITHOLOGICAL CHARACTERISTICS OF THE MIOCENE CHEMICAL DEPOSITS WITHIN THE FORK OF THE VISTULA AND SAN RIVERS

Summary
The horizon of the chemical deposits constitutes an important structural-lithological element in the Miocene of the Carpathian fore-deep. It is connected with the secondary metasomatic changes leading to the formation of calcium carbonate and of native sulphur deposits owing to the reduction of sulphates.
At present, the horizon of chemical deposits is represented, within the fork of the Vistula and San Rivers, by gypsums, post-gypsum, barren and sulphur- bearing limestones, marls and marly clays with intercalations and fragments of limestones (Fig. 1). The extent and the spacial forms, as well as the secondary changes are closely connected with the morphology of the Miocene substratum.
In the zone of relative elevation of the substratum (Cambrian) surface reduced profiles of gypsums may be observed. In the profiles of chemical (sulphate) deposits the following types of gypsums may be distinguished: a) macrocrystalline gypsums; in the lower part of the profile also selenite gypsums,
b) compact, fine stratified gypsums; in the upper part of the profile also with intercalations of gypsum breccia.
To the gypsum types mentioned above, correspond the following post-gypsum limestones:
a) vuggy, porous, calcitized limestones with preserved pseudomorphs after selenites,
b) fine stratified and brecciated limestones after compact, stratified and brecciated gypsums.
The process of metasomatic alterations is conditioned by suitable structural arrangement (Fig. 2), by the presence of screening and reservoir rocks, as well as by the inflow of bitumens, and the environment of mineral waters.
Sulphur distribution in limestones is irregular (Fig. 3).
An accumulation of native sulphur took place due to the bacterial-reduction processes, under influence of bitumens, epigenetically in relation to the original gypsums.

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