歧口凹陷古近纪同沉积断裂对层序和沉积体系的控制

通过对歧口凹陷古近纪的构造格架和主要同沉积断裂的构成和特征分析，指出区内的主要同沉积断裂及其形成的断裂坡折带对古近纪层序和沉积体系的分布起重要控制作用。F1断裂带和东北部盆缘断裂带北段共同控制着北部深洼的沉积充填；东北部盆缘断裂带南段的活动性决定着北次洼的发育；南次洼的发育主要与低凸起周缘断裂带的活动有关。东北部盆缘陡坡断裂坡折带控制了近岸水下扇和扇三角洲体系的发育；西南断阶带的F2断裂坡折控制了辫状三角洲和滨浅湖沉积体系的发育，F1断裂坡折控制低位扇和深湖、半深湖沉积发育以及向凹陷中心方向共生的前三角洲滑塌浊积体系；低凸起南缘断坡带在古近纪早期控制南次洼的扇三角洲或小型水下扇的发育。西南断阶带和F1断裂与东北盆缘断裂交汇处是寻找砂岩油气藏的有利区域。

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 FI 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.