Problemy genezy i wieku koncentracji siarki

Abstract

PROBLEMS OF GENESIS AND AGE OF SULPHUR CONCENTRATIONSummaryOn the analysis of the epigenetical processes leading to the concentration of sulphur the present author tries to explain the time of their occurrence. As yet, there are no direct methods, which would allow the time of formation of sulphur concentration to be determined, or the initia1 period of this process to be explained. At present, there are only indirect methods, which relate the formation of sulphur with the developed geological phenomena. Based on the results of the work carried out by geologists interested in the problems of sulphur origin, the author presents the main geological factors which decide upon the possibility of the development of metasomatic processes of calcium sulphates:1. Palaeogeographical conditions under which sulphate formations (gypsum, anhydrites) can develop to be covered later by a tight mantle of clay formations. 2. Presence of hydrocarbons in the underlying strata. 3. Tectonic processes that lead to the formation of faults, migration paths of bitumens towards gypsum and anhydrites or to the formation of hydrocarbon traps (anticlines) at the bottom of gypsum. 4. Hydrogeological conditions that facilitate an uninterrupted inflow of oxidized surface waters which are a deposit-building factor (oxidation of sulphuretted hydrogen in the deposit), and later on – preservation of static – not renewed – waters, which play a role of a protecting factor. W.Teisseyre (1921) was the first geologist to frame a hypothesis suggesting a relationship between the concentration of sulphur and the faults. In the deposits Posądza and Czarkowy the faults were thought by him to be pathos of bitumen migration to initiate processes of changing gypsums into sulphur. Already W. Kondaki (1883) emphasized the role of water in sulphur formation, pointing that the processes of sulphur formation may take place in the aqueous solution of gypsum only. The research workers interested in the genesis of sulphur concentration, the followers of the theory of epigenesist still at present are of the opinion that water is one of the indispensable factors which make the formation of deposit possible. J. Czermiński and S. Pawłowski (1961) were first to emphasize the role of water as the factor protecting deposits. This role is played by static waters, still not renewed ones. The significance of the renewed waters flowing from the earth`s surface, as the proper deposit-building factor, has been explained in the papers by J. Czermiński (1968 a and b). It had been ascertained previously (L. Zejszner, 1863) that the time of development of the sulphate facies in the basin corresponded to the Tertiary; later on, however, other investigators referred it to the Tortonian (Badenian).  Thus, it may be said that the determination of the formation time of faults and of geological conditions markedly determines the period in which the metasomatic processes of gypsums have begun. The age of the tectonic processes is thought by different scientists to be Tortonian (Badenian) – Sarmatian. The age of the proceses which created hydrogeological conditions favourable for the formation of deposits is to be explained at present. The development of river beds is thought by the present author to be the only (or one of the most important) factor which resulted in the erosion of deep incisions in the Tortonian (Badenian) and Sarmatian clays that cover the deposit formations. i.e. a factor responsible for the development of paths for the infiltration of waters. Such a suggestion is due to the occurrence of the known sulphur deposits in the vicinity of big rivers (Fig. 1).The four sulphur deposits (Piaseczno, Posądza, Czarkowy and Dobrów-Grzybów) are characterized by such a scheme of geological structure, which allowed the outcrops of the underlying formations enriched with surface waters to be uncovered.Such a model of geological structure can be observed in the West Ukraine deposits. Identical water conditions are noted in the American deposits (region of Rustler Springs) and probably also in the deposit Mishraq (Irak). To explain this problem completely one has to interpret the history of the evolution of river beds which supply oversized waters into gypsum or anhydrite series. Based on the available results of studies carried out by geomorphologists, the present author makes a hypothesis, exemplified by the region Piaseczno-Machów, that the deepest incision in the urstromtal, and the strongest erosion of the Tortonian (Badenian) and Sarmatian formations took place approximately 300 000 years ago. This would also be the approximate date at which the process of concentration of sulphur in the Miocene formations of the northern marginal zone of the Carpathian Foredeep began. This hypothesis is to some extent proved by the studies made by H. M. Feely and J. Kulp (1957), according to which the sulphur deposits in the Gulf Coast "have been produced by Desulfovibrio bacteria" in a span of time lesser than 1 million years. The formation of sulphur occurrences, deep in the Carpathian Foredeep, is related by the present author with the time when tectonic forces began to sink the foredeep, i.e. the Tortonian (Badenian) – Sarmatian time.