Geological Genesis Of The High Sulfur Coal From Southwestern Guizhou-analysis Of Pyrite And Sulfur Isotope

In this thesis, the geological genesis of high sulfur coal from SouthwesternGuizhou has been studied by using instrumental neutron-activation analysis (INNA),SEM+EDX and thermal analysis (TG/DTG/DSC) and the concentration of major, rareearth elements and trace elements as well as the isotopic composition of pyrite in highsulfur coal has been determined. The main conclusions were as follows:(1) The geochemistry of elements in high sulfur coal has been studied. The formof sulfur in high sulfur coal is dominated by pyritic sulfur and the contents of V, As,Mo, Sb, U, Cr and Ni in high sulfur coal from Southwestern Guizhou are higher thanthe arithmetic means for the corresponding elements in Northern China and commonChinese coals. The source of trace elements was controlled by source rock andhydrothermal fluid.(2) The modes of occurrence of pyrite and the relationship between pyrite andcoal matrix were revealed. It is difficult to find finer-grained pyrite withwell-developed crystal present in coal and finer-grained pyrite in coal is of strongactivity due to the impacts of reciprocal organic matter-pyrite interactions. Thermalanalysis of coal indicates that pyrite can promote the pyrolysis of coal andcoal-derived pyrite has a greater promotion than mineral pyrite.(3) Sulfur isotopic difference of coal samples between Southern China andNorthern China and sulfur isotopic composition of high sulfur coal from SouthwesternGuizhou have been discussed. Compared to the coal in Northern China, the coal in theSouthern China is depleted in34S and the δ34S values of which are, in general,＜0‰.The δ34S values of coal from Guizhou are variable, which is similar to that of golddeposit and pyritic deposit, indicating that the source of sulfur in coal is complex, andmay be derived from mixing of mantle-source, seawater sulfate and biological-genesissource.(4) Compound geological genetic model affected by both seawater with highsulfur in Southwest Guizhou and Emeishan basalt has been proposed. The formationof high sulfur coal in Southwest Guizhou has a variety of controlling factors, and thefactors are as follows: The sulfur-containing plants, the invasion of seawater duringpeat accumulation, the halmyrolysis of Emeishan basalt containing high sulfur on thebasement of the coal-bearing basin, the infiltration of seawater sulfate through theroof of coal seam after coal formation and the effect of the sulfur rich hydrothermal fluids leached from the Emeishan basalt basement during the later tectonic movement...