中文摘要：

大歧口凹陷位于渤海湾盆地黄骅坳陷中北部，是中新生代叠合盆地中新生界沉积最厚的凹陷。本文基于大量二维、三维地震削面和钻井资料，从凹陷主控断裂活动性、沉积沉降中心分布和构造格架等方面，侧重对大歧口凹陷新生代构造演化过程和原型盆地类型进行研究。认为：1）大歧口凹陷构造单元有4级，凹陷具有“东西分带、南北分块”的平面构造格局和北断南超箕状断陷的剖面结构。2）凹陷内断裂有4级，主要断裂的规模、活动期次和断裂活动具有演化的阶段性和空间的迁移性，典型构造带活动性具有由北往南迁移的特点。3）新生代期间整个大歧口凹陷的沉积沉降中心均在东部海域的歧口主凹内，但整体具有往南迁移的趋势。4）凹陷经历了拓展裂谷、拉分断陷、箕状断陷和碟状坳陷4个构造演化阶段，断陷阶段在整个构造演化时期意义重大，且具有走滑拉分特点。故认为大歧口凹陷原型盆地是一种“板内拉分盆地”。

英文摘要：

The Great Qikou sag is located at the north-central of the Huanghua depression of the Bohai Bay Basin, being a Cenozoic basin superimposed on top of the Mesozoic basin. Based on a large number of 2D, 3D seismic profiles and drilling data, this paper focuses on the structural framework, characteristics of faults, and migration of depocenters and subsidence centers to analyze the tectonic evotion and prototype basin of the Great Qikou sag. Conlusions are as follows： 1）The Great Qikou sag includes four orders of tectonic units, resulting in the zonation in E-W direction and blocking in S-N direction in plane view and half-graben architecthure in profile. 2） The Great Qikou sag includes four orders of faults. The major faults are characterized by multiple-stage evolution and spatial migration in the sizes and activity, and the activity of major tectonic belts migrated from north to south. 3） The Cenozoic depocenters and subsidence centers were located at the eastern part of the Great Qikou sag, and the whole sag shows a trend of southern migration. 4）The structural evolution of the Great Qikou sag can be divided into four stages： Eocene propagating rifting, Early Oligocene pull-apart graben, Late Oligocene half-graben, and Miocene-Pleistocene thermal subsidence under dish-like bukling. Late Oligocene property is obvious during the rift stage. The Great Qikou sag is considered to be an ＂intraplate pull-apart basin＂ in such geological settings.