CONTROLS OF PALEOGENE SYNDEPOSITIONAL FAULTS ON THE SUCCESSIONS AND DEPOSITIONAL SYSTEMS IN THE QIKOU DEPRESSION, BOHAI BAY

This paper systematically analyzes the Paleogene tectonic framework and organization and pattern of major syndepositional faults in the Paleogene Qikou depression and notes that the major syndepositional faults and fault slope breaks in the study area exerted important controlling effects on the Paleogene successions and distribution of depositional systems.Fault F₁ and the north segment of the northeastern basin-marginal fault controlled depositional filling of the deep northern depressed part of the depression;the activity of the south segment of the northeastern basin-marginal fault determined the development of the north subbasin and the development of the south subbasin is mainly related to the activity of the low rise peripheral fault zone.The northeastern basin-marginal steep slope break controlled the development of the inshore subaqueous fan and fan delta system;the slope break fault F₂ in the southwest fault step zone controlled the development of the growth of the braided delta and lakeshore and shallow-lake deposition systems;and the slope break of fault F₁ controlled the deposition and development of the lowstand fan and deep and hemi-deep lake deposition and the prodelta fluxoturbidity system;the southern low rise peripheral slope break zone controlled the development of the fan delta or small subaqueous fan in the southern subbasin at the early stage.The southwest fault step zone and the position of intersection of fault F₁ and the northeast basin-marginal fault are favorable sites for looking for potential sandstone reservoirs.