Stratigraphic division and correlation of the Upper Jurassic-Pliocene in the Dunhua basin

The authors used the field data, seismic data, coal field drilling data and paleontological data to compile and analyze the representative stratigraphic division schemes for the Dunhua basin-coal prospect area at peripheries of the Songliao basin, and got the following understandings: (1) the age of the Huichun Formation is Eocene-Oligocene;(2) the Upper Cretaceous Longjing Formation may not exist in the basin; (3) the upper member and lower member of the so-called Mao'ershan Formation should be assigned to the Quanshuicun Formation and Changcai Formation;(4) the Dalazi, Quanshuicun, Changcai and Tuntianying formations do exist in the basin, of which the Dalazi Formation and Changcai Formation might be Early Cretaceous Aptian-Albian and Berriasian-Aptian in age respectively according to the lithostratigraphic and biostratigraphic correlation between the Dunhua basin and its neighboring basins;(5) the wrong uses of some local formation names at several sites of the basin are revised; and (6) a stratigraphic sequence is established in the Dunhua basin, which may be used for reference at present.