THE STRATIGRAPHIC BASE LEVEL CYCLE DIVISION AND COAL ACCUMULATION REGULAARITY OF PERMIAN IN HUAINAN COALFIELD

The Permian in Huainan coalfield is a set of deltaic-coastal deposition.Using the principle of stratigraphic base level,this paper analyzes the base level cycles in different orders in the Permian of the Huainan coalfield based on the drilling cores and log curves.Three orders of base-level cycles,the short-,mid- and long-term,can be recognized in the studied profile.On the basis of base-level correlation,the high-resolution sequence stratigraphic framework in the studied area is established.It is shown that the coal accumulation occurs in a certain place of the base level cycles.The later stage of mid-term base-level cycle packed on the long-term base-level fall is favorable for coal accumulation.