东营凹陷主干边界断层（带）构造几何学、运动学特征及成因解释

东营凹陷是由西部和北部的伸展边界断层控制发育的复式半地堑。凹陷北部边缘的陈南断层(带)、西部边缘的平南断层(带)和高青断层等主干边界断层的产状多变。在区域尺度上，主干边界断层总体走向西段为北东向、中段为近东西向、东段为北西西向；在制图尺度上，断层面为呈波状起伏的铲式断层面，发育有侧向和斜向断坡。不同走向的断层在古近纪同时具有正断层位移特征，显示出双向伸展的构造变形格局。对主干边界断层上盘的层序充填特征及沉积中心的迁移规律的分析表明，始新世主干边界断层主要为北西—南东向伸展位移，渐新世主要为近南北向伸展位移。这种双向伸展变形的运动学特征，可以用区域北西—南东向引张作用和北北东向深断裂(如郯庐断裂带)右旋走滑诱导的近南北向引张作用的双重动力学过程叠加来加以解释。图4参13

Geometry, kinematics and mechanism interpre-tation of the major boundary faults in Dongying Sag

Dongying Sag is an Eocene multiple graben controlled by extensional faults along the northwest and north margins. The structural contour map of fault surface depicted the diverse attitude of the major boundary fault. Regionally, the fault strike extended towards northeast in the west segment, towards east southeast in the middle segment and towards southeast in the east segment. In a map scale, the 3 D geometry of the major boundary fault was a sinuate listricfault with some lateral and oblique ramp. The faults with various tending were synchronously of normal fault displacements during the Eocene so that the structural pattern was an extensional structure with two direction. The distribution and migration of the depoaxes in the hanging wall of major boundary fault showed that the dominating extension seemed to take in NW SE during the Eocene and in S N during the Oligocene. The extension deformation field with two direction could be interpreted by a model which the local S N extension derived from right lateral slip movement of NNE deep fractures (e.g. Tanlu deep fracture) superposed on regional NW SE extension derived from mantle uplifting during the Eocene.