THE TYPE AND EVOLUTION OF Ⅱ₁ COAL SWAMP IN SHANXI FORMATION IN HENAN PROVINCE

The type and evolution of Ⅱ₁ coal swamp of Shanxi formation（Low Permian）in Henan Province can be divided into three area clearly.In the north area,Ⅱ₁ coal is formed from fresh forest peat swamp which develops from upper deltaic plain.In the west area,Ⅱ₁ coal is formed under herb and forest peat swamp which is developed from lagoon and ended by a short transgression.The regression is at the middle period of coal formation.The Ⅱ₁ coal forming plant of low subbed is herb.In the middle and east area, Ⅱ₁ coal is formed from fresh forest peat swamp which is developed from tidal flat and ended by a short transgression.The upper subbed of Ⅱ₁ coal is formed under salt peat swamp.