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(K

1

) and tuff layer(K

2

) 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(M5

1

) could be subdivided into four beds(M5

1

1

M5

2

1

M5

3

1

and M5

4

1

)

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.M5

1

1

is rich in kaolinite

poor in illite and has no chlorite;M5

2

1

has plenty of illite and kaolinite but no chlorite;M5

3

1

contains almost no clay minerals;in M5

4

1

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.