Geochemical Characteristics Of The Superhigh-Organic-Sulfur Coals From The Late Permian In Heshan,Guangxi Province

The formation of superhigh-organic sulfur coals has its unique geological origin,so this article takes the coal samples of Shicun and Heli Mine from Heshan coalfield in Guangxi as research objects,and discuss the sedimentary environment,coal-forming parent material and possible organic sulfur source by using industrial analysis,microscopic observation,organic geochemical analysis and other analytical methods,the results are as follows:Firstly,according to the data of the industrial analysis and the major elements determination of the samples,the total sulfur content in the study area exceeds 4%,maximum of 9.77%,average organic sulfur content is 84.47%,and the average vitrinite reflectance is 1.76%,the coals belongs to superhigh-organic sulfur and higher degree of metamorphism coals.Secondly,Unresolved Complex Mixtures?UCM?bulge is obvious in the saturated hydrocarbon chromatogram,Pre-peak type and Bi-peak type are distributed.The main carbon peaks of the Pre-peak type are C₁₆,C₁₇,C₁₈,and the Bi-peak is C₁₈,C₂₇.Meanwhile,regular sterane C₂₇,C₂₈,C₂₉ showed a“V”type distribution,and some terpenoid biomarkers,including ones frequently encountered in the geosphere?e.g.,cadalene,retene and dehydrorosin abietane?,it indicates that parent material of double input including lower aquatic organisms and high plants.The distribution of hopane in C₃₁^C₃₅ decrease progressively and ratio of pristane to phytane shows that there are certain oxidation conditions during the forming of coal.Thirdly,the aromatic hydrocarbon compounds are mainly sulfur compounds,with the relative content of 64.17%-89.28%,which is accordance with the proportion of organic sulfur in coal.In the naphthalene series,MNR and DNR-1 indicated that the samples were in the late stage of thermal evolution;the content of methylphenanthrene showed 9-MP>1-MP?2-MP>3-MP,which also shows that the organic matter is mainly low organisms,supplemented by certain higher plants;There is a significant positive correlation between the biphenyl series and the dibenzothiophene?DBT?,and the DBT is highest in the three fluorene series;chrysene,pyrene,fluoranthene were detected in the samples,five-ring and six-ring aromatic hydrocarbons distribution indicated magmatic hydrothermal played an important role in the late diagenetic stage influenced by magmatic hydrothermal.Fourthly,in addition to the sterane maturity parameters C₂₉9 20S/?20S+20R?and???/????+????,methylnaphthalene,methylphenanthrene and rearrangement hopane can also capable of reactant thermal evolution of the maturation-high maturation stage.Fifthly,sulfur containing compounds are not only dibenzothiophene,benzonaphthothiophene,but also benzodibenzothiophene,dinaphthothiophene,dihydrodinaphthothiophene and methylphenanthrothiophene and their alkyl substituents.