Stosunki izotopowe siarki i węgla w rudzie siarki i utworach jej towarzyszących a geneza złóż siarki w Polsce

Abstract

 ISOTOPE RELATIONSHIPS OF SULPHUR AND CARBON IN SULPHUR ORE AND IN ITS ACCOMPANYING FORMATIONS VERSUSTHE ORIGIN OF SULPHUR DEPOSITS IN POLANDSummaryThe article deals with the origin of sulphur deposits, and is based on the research of isotope relationships of sulphur in sulphates, native sulphur and carbon in carbonates.So far the results of partial research on the isotope relationships in Polish sulphur have been published only by physicists: J. Złotowski, A. Stroka and K. Zboiński. A systematic research of the sulphur and carbon isotopes found to occur in the carbonate ores of sulphur has been initiated by Prof. Dr Żuk in Lublin.A number of methodical papers have been published, some of them devoted to the origin of the Tarnobrzeg sulphur deposit (Piaseczno-Machów) thus proving the thesis of Polish geologists (beginning with Z. Suszycki, 1876) that the sulphur deposits in Poland were formed in an epigenetic process of gypsum reduction by hydrocarbons.The present article is based on an ample analytical material (more than 170 samples). Analyses, using mass spectrometer Mi-1305, were made by a group of physicists under the leadership of Prof. Dr W. Żuk.Samples were taken especially with the area of the previous opencast at Piaseczno, mainly because of the approaching liquidation of this object. For comparative purposes sample were taken also at other occurrence sites of sulphur in the Miocene of the Carpathian foredeep in Poland.The sampling comprised samples of native sulphur, dust sulphur, compact (waxy) sulphur and crystalline sulphur. Moreover, there were taken samples of various types of sulphur carbonate ores, limestones that accompany the sulphur deposits (the so-called post-gypsum limestones and post-sulphur limestones), and sulphate minerals found in the sulphur deposits. Samples of macro-crystalline and crypto-crystalline gypsums, the so-called laminated gypsums, were taken not only from the sulphur deposits, but also from the sulphurless gypsums of Miocene age, which occur in a sheet-like manner (coarse-crystalline at the top, and laminated at the bottom) within the area between Wiślica and Cracow (the Działoszyce trough).The results of the research on the relationships of sulphur and carbon in the crbonate deposits are shown in tables and diagrams. According to the degree of sulphur and gypsum crystallization, and to the chemical composition of sulphates the differentiation in isotope composition can easily be seen (Fig. 8).However, the crystallization processes are not directly responsible for the partition of the sulphur isotopes. The differentiated relationships of isotopes in sulphur depend upon the solution and crystallization process, in the course of which the successive phases reveal lighter and lighter isotope that can easily be removed by solutions.Apart from the precise analysis of the results obtained the studies required their correlation with the thoroughly investigated geological structure of the sampled areas. Such an approach was a basis to explain the reasons of the occurrence of differences in mean values of d34S‰ observed in various parts of the deposit at Piaseczno by W. Żuk, S. Hałas, J. Lis and J. Szaran (1973).To explain some difficult problems the authors introduced a method of using the so-called indicator samples, the chemical and mineral compostion of which, as well as their texture and structure, particularly, however, their geological position allow their origin to be unquestionably determined.The isotope relationships of the investigated Miocene, Cretaceous, Zechstein and Devonian sulphates are contained in these intervals which are known for the deposits of the same age in the world's literature.The isotope relationships of d34S‰ and d34C‰ in the Machów deposit or in that in the region of Czarkowy (Stanisławice) have demonstrated that both carbonate ore components and native sulphur were formed during epigenetic processes of gypsum reduction by gaseous hydrocarbons. This process, as proved by a uniform composition of d34S‰ was long-lasting and stable, typical of greater depths. This allows us to draw conclusions as to the identity of conditions of sulphur formation at Machów and Senisławice (region of Czarkowy).In the deposit "Piaseczno" two genetic types of sulphur and the three genetic types of limestones occur.The first type contains sulphur oxidized "in statu nascendi" at deeper (eastern) portion of the depostit, and enriched in its heavy isotope. The second type is represented by “light” sulphur, formed, in the region, of exposures, of allochthonous sulphatted hydrogen within heterogenous limestones.To the genetic types of limestones belong: 1) limestones, formed in a sedimentary way within the Miocene marine basin together with gypsums (represented by sample No 16); 2) limestones formed due to the filtration of surface water into the outcrops of deposit. The mechanism of infiltrating CaCO3 into the deposit was as follows: waters rich in CO2, migrating from the surface, dissolved CaCO3 existing in the marly overburden of the gypsums. Later on CaCO3 precipitated in the porous formations of the outcrops. Calcium carbonates (gypsums), as in the area of outcrops, were dissolved by the same waters and as a solution migrated gravitationally along  the dip, down to the deeper (eastern) parts of the deposits; 3) type metasomatic limestones, making the only carbonate component of the sulphur ore found at a greater depth at Piaseczno. At the northern wall of the opencast this type of limestones maybe makes a minimum admixture.