An Assessment of the Chemical Characteristics of Early Diagenetic Processes in a Geologically Well-defined Brown Coal Basin

Abstract

The characteristics of early diagenetic processes, which influenced the composition of the organic matter of coals from the Krepoljin coal basin, Serbia, Miocene age was assessed by statistical correlation analysis and multivariate principal component analysis. The complexity of processes in a coal-forming sedimentary environment has been paid special attention to obtain the most possible reliable interpretation of these early diagenetic processes and, therefore, this investigation was performed by applying principal component analysis. The principal components, which are defining the coals and promoting individual early diagenetic processes, were the precursor materials and environmental factor, respectively, represented by higher plants, algae, and molds—expressed by the relative contents of the Cs29-, Cs28-, Cs27-steranes, respectively, and the content of organic sulphur—Sorg, average content 166 ± 101 μmole/g. The main and highly interrelated effects of the higher plant material were as follows: (i) increase of the sulphur content of coal organic matter, (ii) promoter of sulphate reducing conditions, and (iii) establishment of the H/C- and N/C-ratios of organic matter. Pyrite formed by the participation of Sorg.