Geological genesis of the high sulfur coal from Southwestern China

摘要

The southwest region,one of the 3 largest acid rain regions in the world,is also China's major high sulfur coal district.Studies on the genesis of high sulfur coal are of great significance in promoting the high sulfur coal development and reducing coal pollution.In the present study, sulfur isotopic differences of coal samples between Southwestern China and Northern China,and sulfur isotopic composition of high sulfur coal from Guizhou have been discussed.We found that the coal in Southwestern China has a higher sulfur content but is depleted in34S, compared to the coal in Northern China.The δ34S values of coal from Guizhou are variable,generally ＜0％,which is similar to that of gold deposit and pyritic deposit in this area.This indicates that the source of sulfur in coal is complex,and may be derived from the mixing of mantle-sulfur, seawater sulfate and biological-genesis sulfur.It is discovered that a variety of factors control the formation of high sulfur coal in Guizhou.These factors are as follows: the sulfur-containing plants, the invasion of seawater during the peat accumulation,the halmyrolysis of Emeishan basalt containing high sulfur on the basement of the coal-bearing basin, the infiltration of seawater sulfate through the roof 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.Based on the above analysis and the previous research results, considering the influence of both seawater and Emeishan basalt, we propose a compound geological genetic model about Guizhou high sulfur coal.