Sequence stratigraphic analysis and sedimentary study on Yaojia formation in northern Taikang area of northern Songliao basin

In order to clarify the sedimentary types and the evolutionary rule of Yaojia formation in northern Taikang area,guided by the sequence stratigraphic theory,this paper divides the Yaojia formation into three sedimentary sequences by means of the sequence stratigraphic classification and correlation. The types of sedimentary facies developed in Yaojia formation include deltaic plain subfacies and deltaic front subfacies.Of the two subfacies above,the deltaic front subfacies can be further subdivided into underwater distributary channel developing area and river mouth bar developing area.The process of the sedimentary environment evolving from deltaic plain to deltaic front embodies the deepening process of the water body in the basin during the depositional period of Yaojia formation.