饶阳凹陷中部地区古近纪构造变形及控制因素

Paleogene Deformation and its Control Mechanism in the Central Part of Raoyang Sag

饶阳凹陷中部地区由北向南古近纪构造变形存在着明显差异。本文基于三维地震地质构造解释详细研究了饶阳凹陷中部地区古近纪沉积序列、凹陷结构特征及主干断层活动性差异。研究发现,位于饶阳凹陷东部边界的献县拆离断层,在新生代仍然显著活动,并控制饶阳凹陷的盆地变形。运用变形平衡原理恢复各地层沉积时期拆离断层深度及形态变化,探讨饶阳凹陷中部地区古近纪构造变形与拆离断层构造变形间相互关系。研究结果表明,受拆离断层面空间构造形态变化的影响,饶阳凹陷中部地区由北向南古近纪断陷结构明显不同;拆离断层上盘的主干断层在孔店组-沙四段(E_(1-2)k-E_2s^4)、沙三段-沙二段(E_2s^3-E_2s^2)、沙一段-东营组(E_3s^1-E_3d)沉积期非继承性活动,导致地层沉积中心发生自东向西迁移,并且局部地区由于受拆离断层下部伸展穹隆的隆升而造成上覆沉积盖层遭受剥蚀。拆离断层及上盘主干断层活动差异共同控制着饶阳凹陷中部地区古近纪的构造变形和演化。构造几何学及运动学特征的分析为探讨华北克拉通新生代构造演化及油气聚集特点奠定了重要基础。

Various Palaeogenic deformations have been recognized in the central part of the Raoyang Sag.Based on seismic interpretation,the sedimentary sequences,structure features and activity of main faults have been studied.The results show that the Xianxian detachment fault,which is located in the eastern boundary of the Raoyang Sag,was still active during the Cenozoic and controlled the basinal deformation.The detachment depth and deformation of the Xianxian detachment fault are discussed based on the area-balance theory.The results reveal that patterns of the Paleogene structures vary considerably from the north to the south.Activity of the main faults in the hanging wall of the Xianxian detachment led to a westward migration of the deposition center.On the other hand,the uplifting of the dome related to the detachment resulted in fast denudation of the overlying sediments in locals.The deformation of detachment fault and activities of the major faults controlled the Paleogene deformation in the central part of the Raoyang Sag.