Sulfur speciation and isotopic composition in a vertical profile of the main coal seam of the North Bohemian brown coal basin and their paleogeographic interpretation


Authors: Mach K, Žák K, Jačková I

Published in: Bulletin of Geosciences, volume 74, issue 1; pages: 51 - 66;

Keywords: North Bohemian brown coal basin, S isotopes, S speciation in coal, paleogeography,

Export to RIS



In 49 samples of coal from the main seam of the Tertiary North Bohemian brown coal basin contents and isotopic compositions of the sulfidic, organically bound, sulfate, and total sulfur have been determined upon sequential separation. Isotopic composition of the dissolved sulfate originally present in this fresh-water sedimentary basin is best reflected by the delta;34S values of organically bound sulfur, while the isotopic composition of syngenetic, diagenetic and epigenetic sulfides is more influenced by isotope fractionation during bacterial sulfate reduction.
The isotopic composition of organically bound sulfur exhibits a significant decrease of delta;34S values with decreasing depth (i.e. decreasing age of the coal) within the main coal seam. This trend is interpreted as a result of paleogeographical changes during the formation of the main seam.