Sequence stratigraphy and coal accumulation law of Taiyuan-Shanxi Formation in southwest of Jungar Coalfield

In order to discuss the thick seam distribution law in the sequence stratigraphy framework and the control factors ofthe coal accumulation role,the high resolution sequence stratigraphy theory and method were applied to the study on the cal measures of TaiyuanShanxiFormaton at the southwest of Jungar Coalfeld. The study results showed that based on the regional unconformity surface,the turn around surface in thetransgression direction,the erosion surface of the incised valley,the paleosol and other sequence stratigraphy surface,the stratigraphy in TaiyuanShanxiFormation were divided into three three-grade sequence stratigraphy and five fourth-grade sequence stratigraphy.The seams in the studyregion mainly distributed in the high level system region and secondary were the transgressive system region.At this moment the foundation subsidence was gently slow,the accommodation space increased rate and the peat accumulation rate was basically kept in the balances and would be favorable to the coal formation. The thick seams in the high level system region were composed with the seam complex formed with the mult .ycles of the base level. The further analysis on the three grade secuence S皿2 stratigraphyseam thickness and the percentage content of the sandstone showed that the thick coal seam was formed in the peat swamp environment with a medium setlement rate of the base foor and a less oontent of the sandstone. The base level of the ofishore region controlled the variation of the groundwater level and would fnally control the peataccumulation and preservation.