济阳坳陷构造特征及形成机制讨论

CHARACTERISTICS OF JIYANG DEPRESSION AND MECHANISM OF BASIN FORMATION

济阳坳陷总体表现为由多个次一级北断南超的半地堑凹陷组成。坳陷内的凸起构造呈近NE向的排列,单个凸起构造呈东西向展布。东西向构造为东营凹陷的主体构造方向,西部的几个凹陷则为北东向展布,坳陷区内的断裂构造以NE向断层为主。坳陷以伸展构造为主,同时发育有走滑构造和重力滑动构造。盆地演化经历了印支期NE向挤压、中生代中期裂陷、中生代晚期构造抬升、古近纪强烈断陷和新近纪整体坳陷等几个阶段。盆地的最终成型是地幔抬升产生的裂陷和走滑断裂产生的拉分联合作用的结果,来自东南方向的挤压作用是形成区内北断南超半地堑盆地的重要因素。

Jiyang depression consists of a number half-graben sags and some swells. The swells are distributed along NE direction. Single swell extends in EW. EW trending faults are the major structures in the Dongying sag. In the western part of the Jiyang depression, the sags are distributed in NE, and the NE faults are the major controlling structures. Extensional structures predominate in Jiyang depression, while few strike-slip structures and gravitational slip structures also occur in this depression. Jiyang depression has undergone the compression phase along NE direction in Indosinian orogeny, the rifting phase in middle Mesozoic, the uplifting phase in late Mesozoic, strong fault basin phase in Eogene and the integral depression phase in Neogene. The formation of Jiyang depression was due to the rifting of lithosphere caused by mantle uplift and to the pulling-apart effect of strike-slip faults, and the extrusion originating from the Pacific Oceanic plate controls the formation of the half-graben basin.