SEQUENCE TYPES AND SEQUENCE STRATIGRAPHY OF THE DOLOSTONES IN CONTINENTAL OIL-BEARING BASINS:AN EXAMPLE FROM THE UPPER PART OF THE THIRD MEMBER OF THE SHAHEJIE FORMATION,WESTERN DONGYING DEPRESSION,SHANDONG

The analysis of the sequence types of the dolostones in the upper part of the third member of the Shahejie Formation in western Dongying depression,Shandong shows that the characteristics of the dolostone sequence in the study area differ greatly in various boreholes.These dolostones are commonly interbedded with sandstones,conglomerates, siltstones and mudstones.In this paper,the stratigraphic theory was employed to the se-quence stratigraphic analysis of the dolostone horizons,which are interpreted as the prod-ucts of the highstand systems tract during its later stage,and constituent elements of progradational parasequences.