Sulphur isotopes in anhydrite from badenian (Middle miocene) salts of the hrynivka area (Ukrainian carpathian foredeep)

Abstract

Ten new determinations of the stable sulphur isotope content of anhydrite from Badenian rock salt in the Hrynivka 525 borehole (Ukrainian Carpathian Foredeep) show that δ 34 S values in anhydrite range from +20.2 to +22.7%o and the average value of δ 34 S is +21.4 ± 0.3%. Those values are similar to those of the Neogene marine sulphates. Comparison to other geochemical data (chemical composition of the brine contained in fluid inclusions and the bromine content in halite) suggests that the Badenian Carpathian Foredeep evaporite basin was supplied predominately by sea water solutes where, at different stages of salt accumulation, the influence of continental waters with lighter isotopic compositions of dissolved sulphate was important. The isotopic composition of sulphur (δ 34 S) of Badenian seawater, calculated on the basis of sixty analyses of anhydrite related to halite of the Carpathian region, is approximately +20.3%, this value being similar to the sulphur isotopic composition of present-day seawater. The δ 34 S value for Badenian sea water may have been slightly higher if we consider potential changes of the brine composition of salt-bearing basins caused by inflow of continental waters enriched in light 32 S isotopes.