辽河盆地东部凹陷新生代伸展-走滑构造作用及断裂构造特征

Cenozoic extension and strike-slip tectonics and fault structures in the Eastern Sag,Liaohe Depression

基于最新的三维地震资料处理与地震剖面解释、地震相干切片分析和平衡剖面恢复等方法,对辽河盆地东部凹陷所发育的断裂几何形态、盆地演化过程和走滑构造平面特征进行研究,并结合区域板块构造活动背景,分析其对郯庐断裂带新生代时期活动的响应.结果表明:辽河盆地东部凹陷为伸展和走滑两期构造变形叠加的产物,是具有"下断上坳"双层结构的裂谷型盆地.盆地演化过程经历了强烈断陷期(Es3)、区域隆升期(Es2)、断坳转化期(初始走滑期)(Es1)、坳陷沉降期(强烈走滑期)(Ed)和构造反转期(Ng-现今)5个演化阶段.研究区主要发育正断层、逆断层、走滑正断层和走滑逆断层4种断层类型,经伸展间歇期和后期区域挤压作用,发育两期正反转构造.盆地经历的走滑运动过程可细化为初始走滑(Es1),强烈走滑(Ed)和衰减走滑(Ng)3个阶段.

Latest seismic data processing and seismic profile interpretation,seismic coherency slice analysis and balanced profile restoration,had been used to researches on the fault geometric morphology,basin evolution process and planar features of strike-slip structure in the Eastern Sag of Liaohe Depression.In addition,the responses to Cenozoic episodic activities of Tan-Lu fault zone are also analyzed on basis of the background of regional plate activities.The results show that the Eastern Sag of Liaohe Depression is a rift-type basin with two-layer structure,namely,the lower fault-depression and the upper depression subsidence,which had been underwent two-phase tectonic deformation superimposition of extension and strike-slip.The basin has experienced five evolutionary stages,respectively,strong fault depression(Es3),regional uplift(Es2),fault-depression transformation(initial strike-slip)(Es1),depression subsidence(strong strike-slip)(Ed)and tectonic inversion(Ngto present).There are four types of faults including normal fault,reverse fault,strike-slip normal fault and strike-slip reverse fault,and two positive inversion structures by extension diapause and later regional compression.The strike-slip process of the basin can be divided into three stages such as initial strike-slip(Es1),strong strike-slip(Ed)and attenuated strike-slip(Ng).