辽东湾坳陷辽中南洼构造发育演化特征与成因机制

基于最新的三维地震连片资料，通过对辽中南洼断裂体系和地层发育特征的精细解释，明确了辽中南洼的构造发育演化特征，探讨了成因机制。结果表明：辽中南洼发育走滑和伸展2类断裂，主干走滑断裂整体NNE走向，深浅均有发育；伸展断裂主要发育在深部，被走滑断裂切割改造。受控于走滑和伸展作用在不同地区的作用强弱差异，辽中南洼整体东西分带、南北分段，自西向东辽中南洼可以划分为西部斜坡带、中部走滑带和东部斜坡带，东、西两个斜坡带为典型的伸展半地堑，走滑断裂条数的变化、中央走滑断裂的走向弯曲造成了中部走滑带的南北分段性。辽中南洼新生代构造演化可以划分为古近纪孔店组—沙四段沉积期、沙三段—沙一段沉积期、东营组沉积期、新近纪—第四纪4个阶段，经历了伸展断陷、构造转型、走滑—断拗转换、走滑—拗陷的构造演化过程，体现了伸展和走滑作用强弱的时间差异。辽中南洼现今复杂多样而又独特的构造特征并不单纯受控于单一构造背景，而是形成于伸展和走滑应力在时间和空间上的差异复合作用。

TECTONIC EVOLUTION AND FORMING MECHANISM OF THE SOUTHERN LIAOZHONG SAG,LIAODONG BAY DEPRESSION

Based on the conventional interpretation of latest 3D seismic data, the tectonic evolution of the southern Liaozhong Sag is analyzed, and the formation mechanism discussed. The results indicate that two main types of faults, i.e. the strike-slip faults and the extensional faults, are developed in the study area. The strike-slip faults extend primarily along the strike of strata in NNE and cut through both the deep and shallow sequences, while the extensional faults are developed in the deep sequences and complicated by the formers. Under the combined influence of strike-slip shearing and extensional stress, the southern Liaozhong Sag are divided into the western half-graben slope zone, the central strike-slip zone and the eastern half-graben slope zone from west to east, and the central strike-slip zone is further sub-divided into south and north parts according to the change in the quantity and curvature of the central strike-slip faults. The Cenozoic tectonic evolution of the southern Liaozhong Sag have passed through four tectonic evolutionary stages, including the extensional stage (Ek-Es4), tectonic transitional stage (Es3-Es1), strike-slip shearing + extensional stage (Ed), and strike-slip shearing + depression stage (N+Q), based on the tectonic evolution caused by temporal and spatial variation of the strike-slip shearing and extension stress. The present structural pattern of southern Liaozhong Sag is complicated under the control of the temporal and spatial variation of both the strike-slip shearing and extension instead of one stress.