Izotopy stabilne jako źródło informacji o procesach złożotwórczych na przykładzie tarnobrzeskich złóż siarki rodzimej
Abstract
STABLE ISOTOPES AS THE SOURCE OF INFORMATION ON DEPOSIT- FORMING PROCESSES AT THE EXAMPLE OF THE TARNOBRZEG NATIVE SULFUR DEPOSITS
Summary
The updated isotopic studies on native sulphur ore-bodies, including fluids, in Tarnobrzeg are reviewed. The most striking feature of these deposits is a considerable δ34S shift of the total sulphur (weighted sum of HS-, H2S, S0 , SO42-, CaSO4, SrSO4 and BaSO4) to lower values in comparison to Miocene evaporitic gypsum which has δ34S ≈ +23‰.
The present study performed at the UMCS Laboratory shows that the following three secondary minerals (which crystallized in the ore fluid) CaSO4 • 2 H2O, SrSO4 and BaSO4 are highly diff erentiated in δ34S and weakly in δ18O. The secondary gypsum has the lowest delta values, it is isotopically similar to SO42- of the present-day pore Waters (δ34S ≈ +23‰). In contrast, barites have δ34S between +60 and +70‰, while celestites show the isotopic composition between these two extremals. Such differentiation may be explained by isotope equilibrium between SO42- and the sulphate mineral at low temperatures.
The sulphur bearing limestones have range of δ13C from -19 to -48‰ with maximum frequency around -40‰ which indicates the oxydation of light hydrocarbons during reduction process of gypsum.
The isotopic compositions δD and δ18O of H2O of ore fluids may be reconstructed from: I) δD and δ18O of crystallization water of secondary gypsum and 2) δ18O of calcite and aragonite minerals, and perhaps 3) the slope of δ18O vs δ34S of SO42- during reduction. The above sources of information point out on a water isotopically appreciably lighter than SMOW but heavier than a shallow groundwater reflecting the annual average of meteoritic precipitations.
Summary
The updated isotopic studies on native sulphur ore-bodies, including fluids, in Tarnobrzeg are reviewed. The most striking feature of these deposits is a considerable δ34S shift of the total sulphur (weighted sum of HS-, H2S, S0 , SO42-, CaSO4, SrSO4 and BaSO4) to lower values in comparison to Miocene evaporitic gypsum which has δ34S ≈ +23‰.
The present study performed at the UMCS Laboratory shows that the following three secondary minerals (which crystallized in the ore fluid) CaSO4 • 2 H2O, SrSO4 and BaSO4 are highly diff erentiated in δ34S and weakly in δ18O. The secondary gypsum has the lowest delta values, it is isotopically similar to SO42- of the present-day pore Waters (δ34S ≈ +23‰). In contrast, barites have δ34S between +60 and +70‰, while celestites show the isotopic composition between these two extremals. Such differentiation may be explained by isotope equilibrium between SO42- and the sulphate mineral at low temperatures.
The sulphur bearing limestones have range of δ13C from -19 to -48‰ with maximum frequency around -40‰ which indicates the oxydation of light hydrocarbons during reduction process of gypsum.
The isotopic compositions δD and δ18O of H2O of ore fluids may be reconstructed from: I) δD and δ18O of crystallization water of secondary gypsum and 2) δ18O of calcite and aragonite minerals, and perhaps 3) the slope of δ18O vs δ34S of SO42- during reduction. The above sources of information point out on a water isotopically appreciably lighter than SMOW but heavier than a shallow groundwater reflecting the annual average of meteoritic precipitations.