Abstract:

The 1st submember of the 5th member of Upper Majiagou Formation in the Lower Or dovician is the main reservoir of Shaanganning Basin,and its subdivision and corrlation with subsurface counterpart within the basin benefit the establishment of nonhomogeneous geo logical model.Based on the study of the outcrop in Guanjiaya, Xingxian of Shanxi Province.gypsum.pseudocrystal layer(K₁) and tuff layer(K₂) were selected as the main marker horizons,and the argillaceous rock ina,b,c suites of carbonate rocks as subsidiary marker horizions,then the first submember(M5₁) could be subdivided into four beds(M5₁¹,M5₂¹,M5₃¹ and M5₄¹),the result suggest that the bounderies of the beds correspond with the peaks of the curves of their chemical elements,and the beds constitute different clay mineral assemblages.M5₁¹ is rich in kaolinite,poor in illite and has no chlorite;M5₂¹ has plenty of illite and kaolinite but no chlorite;M5₃¹ contains almost no clay minerals;in M5₄¹,kaonite,illite and chlorite could all be found.The different marks and characteristics of the four beds could be seen clearly in well drilling within the basin.therefore they may be considered as foundation and markers for bed subdivision and correlation.