THE SEDIMENTARY ENVIRONMENT AND COAL ACCUMULATION CHARACTERISTICS OF THE COAL BEARING SERIES IN SHOUYANG COAL FIELD，EAST SHANXI

The coal bed in Shouyang coal field was composed mainly of Taiyuan Group(C₃t) and Shanxi Group(P_ls) containing 9 to 14 seams. The abounded coal reserve of this region made itself one of the important bases of en- ergy. The Taiyuan Group in this district can be divided into five complete cycles of sequence. containing 6-8 coal seams, and was made up of light gray, dark gray and grayish black mudstone. siltpelite, carbonaceous mudstone. silt-stone. sandstone, limestone and coal seams. Aaording to the sedimentogaghy, the authors con- sidered environment that Taiyuan goup of this area belonged to the transitional environment deposite. The lower three cycles i.e.the 1st, 2nd. 3rd were built up of continental elastic debris tidal Ilat deposition under marine regression and lower intertidal carbonate under marine inundation, while the upper two cycles (the 4th and 5th) belonged to deltaic deposition. The Shanzi Group in this district containing 3-6 coal seams, consisted of gray and black mudstone, sandy mudstone, carbonaceous mudstone, ailtstone, sandstone and coal seams. On studying its sedimentation mechanism in detail. the authors proposed that the formation of Shanxi Group is not “purely continental”as been known before, but as deltaic deposition. It can also be divided into five cycles (the 6th. 7th, 8th, 9th and 10th) most of them represent developing deltaic deposition ezcept the cycle 6 which showed complete sequence of delta deposition The relationship between the depositional environment and the property of coal seams are as follows: The 15th. 13th, 12th and 11th coal seams. located at the lower three cycles of the Taiyuan Group, were deposited under tidal flat environment. The characteristics of this sequence can be described in following words; the formations below each coal seam belonged to sea ebb sequence its continental clastic debris represent tidal flat