歧口凹陷东营组沉降特征及其成因分析

The Characteristics and Mechanism of the Subsidence of the Dongying Formation in the Qikou Sag

运用区域三维资料和EBM盆地模拟软件,对歧口凹陷三维连片区东营组沉积时期的沉降史进行了模拟分析,并探讨了沉降中心迁移的原因。结果表明,歧口凹陷东营组发育于同裂陷阶段晚期的断拗转换期,沉降特征具有时空差异性,沉降速率时快时慢,不同次凹之间差异较大。从东三段到东一上段,NE-NNE向主干断层控制作用逐渐减弱,沉降中心逐渐减少,并沿东北方向向歧口深凹逐渐迁移。通过对区域断层和沉降特征研究,认为区域断层的差异性活动控制着沉降中心的发育部位,而区域应力场的改变则控制着沉降中心的迁移。

The subsidence history of the Dongying Formation in the Qikou sag is analyzed based on EBM basin modeling and 3D seismic traverse.The controlling mechanism of the subsidence is investigated through studying the regional structures.The results show that the Dongying Formation was formed dring the fault-sag transition in the late stage of faulting.Subsidence characteristics and subsidence rates varied temporally and spatially.There were great differences in subsidence characteristics among sub-sags.From SQEd3 to SQEd1s,the control of the NE-NNE faults on the subsidence faded gradually.The number of subsidence centers reduced while the centers of subsidence migrated northeastwards of the coastal area of the Qikou sag.Based on the characteristics of the regional faults and subsidence,it can be inferred that the locations of the subsidence centers were controlled by divers activities of the regional faults.And the migration of the subsidence centers was controlled by changes of the regional stress field.