Coal petrological characteristics and coal facies of No. 11 seam from the Antaibao mine, Ningwu coalfield, China

Twenty-one coal samples of Seam 11 from the Antaibao Mine, Ningwu Coalfield, Shanxi Province, were analyzed by microscopic method. The macerals were identified and their ratios were calculated. The vitrinite contents decrease and the inertinite contents increase from bottom to top of the seam section. The data were used as indicators in the definition of different types of coal facies and hydrodynamic condition diagrams. The results indicate that the peat moor of Seam 11 might be formed in a regression environment, and it can be divided into 7 secondary regression processes. The peats evolved from low-open moor to dry-forest moor. The water depth of the moor decreased, and activity of water flowing decreased.