Data set on petrological and isotopic composition of some selected lignites, sub-bituminous and ortho-bituminous coals
We present a dataset of petrological characteristics, isotopic composition of carbon (δ13C), and nitrogen (δ15N) in thirty-two coal samples originating from six diverse sedimentary coal basins: Velenje Basin (Slovenia), Laško syncline (Slovenia), Mura-Zala Basin (Slovenia), Istrian Basin (Croatia), Sokolov Basin (Czeck Republic), and Barito Basin (India). These coal samples were obtained from open-pit mines, underground mining areas, and boreholes. Additionally, one coal sample sourced from Indonesia and extracted by the Kideco Company was specifically obtained from Termoelektrarna Toplarna Ljubljana. Before conducting stable isotope analyses (δ13C and δ15N) on various coal samples, the samples were macroscopically determined according to the ECE-UN (1998) classification in terms of ortho-lignite, meta-lignite, sub-bituminous coal, and bituminous coal. The stable isotope composition of organic carbon (δ13Corg.) and nitrogen (δ15Nbulk) in different lignite lithotypes was analyzed using the PDZ Europa 20-20 isotope-ratio mass spectrometer (Sercon Ltd, UK) connected to an ANCA-SL preparation module. The carbon isotopic composition (δ13Corg.) of the samples ranged from -27.9 to -23.6 ‰, while the nitrogen isotopic composition (δ15N) ranged from 1.8 to 7.4 ‰. Higher δ13Corg. values and elevated δ15N values indicate greater bacterial degradation of organic matter. The Raša coals, classified as vitrain samples and formed in an anaerobic marine environment, exhibited the highest δ13Corg. values in the range of -24.0 to -23.6 ‰. The highest δ15N value of 7.4 ‰ (indicating higher mineralization) was detected in a lignite sample from the Velenje Basin. The lowest δ15N value of 1.8 ‰ was observed in Jožef coal sample from the Sokolov Basin, indicating minimal mineralization of organic matter. Further, we compared δ13Corg and δ15N data of plants and coals gathered in this study with previously published data to evaluate microbial degradation. We obtained no correlation between δ13C and δ15N. Moreover, we calculated δ13C in air to determine differences in paleoclimate between coals. The determined δ13C values fall within the typical range of world coal (from -20.9 to -30.7 ‰). Calculated δ13CCO2 ranges from -8.4‰ to -3.4 ‰, which is more positive compared to modern atmospheric CO2 with -8.5 ‰. In conclusion, δ13C and δ15N data, in association with the petrological composition, could be used in paleoenvironmental, paleoclimate, and paleoecology studies, as well as for the clarification of biogeochemical processes in sedimentary basins.
Javna Agencija za Raziskovalno Dejavnost RS
L2-4066, P1-0143, P1-0025