Matter Composition and Two Stage Evolution of a Liangshan Super High-Sulfur Coal Seam in Kaili, Eastern Guizhou

Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus, a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%, from Kaili, eastern Guizhou, was studied using the methods of coal petrology and geochemistry. The results show that the seam was apparently formed in seawater-effected peat bogs that developed in two distinct stages. During the first stage various layers were formed in a supratidal bog and have a composition characteristic of a bog with a gradually decreasing seawater effect, decreasing water dynamics, and an increasingly reductive environment. Layers in the upper seam formed during a second stage in an intertidal bog. These layers are very high in total and inorganic sulfur, the ratios of organic/inorganic sulfur and V/I drop, they are high in coal ash yield and have a high ash component index, considerable barkinite, oxidized and detrital macerals, have a porphyroclatic micro-structure and are rich in pyrite, all of which indicate the coal-forming environment had higher oxidation potential, strong and roiling water dynamics, and intermittent exposure to a sulfur rich environment.