Components of sulfur isotopes and characteristics of sulfur evolution in Wuda Coalfield, Inner Mongolia.

According to the synthetic analysis of coal petrology and the isotopic dete rminations of the organic sulfur and pyrite in the column sections of No. 9 coal seam (the high sulfur coal whose delta(34)S Of organic sulfur is from -12. 3 parts per thousand to 5. 8 parts per thousand and delta(34)S of pyr itic sulfur is from -18. 7 parts per thousand to 1. 1 parts per thousand) a nd No. 13 coal seam (the low sulfur coal whose delta(34)S of organic sulfur is from 9. 6 parts per thousand to 11. 5 parts per thousand and delta(34)S of pyritic sulfur is from 8. 6 parts per thousand to 9. 7 parts per thousa nd) in Wuda coalfield, the characteristics and the genesis of sulfur isotop es in coals were discussed, and then the relationships between the organic sulfur isotope and the pyritic sulfur isotope, and delta(34)S values of org anic sulfur and pyrite and total sulfur were analyzed. The study results sh ow that there are administrative levels in the column section of the coal s eam and anti-directions in the geological history in the sulfur isotope for mation of the high sulfur coal. The administrative levels reflect the open degree of SO42- and H2S in a system and filtration of (SO42-)-S-32 because of the pyrite formation. The anti-direction reflects not only the contribut ions of Fe2+ and SO42- to the high sulfur formation in the initial stage of peat swamp accumulating, but also the major factors of the seawater influe nce and the Fe2+ supplying in the later period of peat swamp accumulation.