Abstract: With control of the structural evolution stages, Qikou sag in Paleogene underwent such sedimentary evolution sequences as semi-arid saucer lake environment in chasmic stage, deep-water lacustrine environment in strongly chasmic environment and open saucer lake environment in late chasmic stage. With control of the basin's palaeotectonic framework, seven sub-structural units can be classified into in this study area for the special distribution of sedimentary facies. Three source systems exist in Qikou sag which controlled the distribution of four sand bodies located at the southwest slope-break zone, the center of southern margin of the sag, the joint of F1 fault and northeastern margin fault and the joint of low swell southern margin fault and northeastern margin fault.

Key words: Qikou sag, Paleogene, palaeotectonic framework, sedimentary evolution, deposit source, sand body distribution