歧口凹陷构造发育演化背景研究 The Background Research of Structure Evolution in Qikou Sag

渤海湾盆地右旋转换伸展作用在古近纪演化时期都存在，变形主要是沙三段沉积时才开始的，早期集中在盆地的西部、渤中坳陷和渤海湾盆地的东部，孔店组很少发育。伸展方式为一个巨大的拉分盆地变形模式。歧口凹陷新生代古近纪发生幕次变化过程；由裂陷I幕向裂陷II幕转变过程，歧口凹陷均发生多个独立沉积单元向单一活动的沉降单元转变。新近纪时期，歧口凹陷结束了古近纪时期的强烈断陷过程，进入了裂后期的热沉降阶段。 The existence of the extensional dextral conversion is true in The Bohai Bay Basin Paleogene, beginning from the three-section of Shahejie formation. The major extensional dextral conversion focuses on the west and east of basin and the central Gulf of The Bohai depression. There are small extensional dextral conversions in The Kongdian formation. The stretch mode of the Qikou Sag is a huge pull-apart basin. There are episodic changes of the Paleogene of Cainozoic; from I episodic of the rift to II episodic of the rift. The Qikou sag changed from plurality of the sedimentary units to the single sedimentary unit in this epoch. After the intense fault depression period in Paleogene, the Qikou sag gets into the thermal precipitation stage in Neogene.