【摘要】 伏龙泉断陷是松辽盆地一级构造单元东南部隆起之上的二级构造单元,构造特征比较复杂。地震剖面解释表明,伏龙泉断陷自白垩纪以来主要经历了4个构造演化阶段:在火石岭组-营城组下部沉积时期为近EW向伸展作用阶段,形成以大型犁式正断层为控陷断层的近NS向箕状半地堑和滚动背斜;在营城组上部-泉头组中段沉积时期为近EW向挤压作用阶段,使早期控陷正断层发生反转作用而转化为逆断层,靠近控陷断层的西部边界由于断层上盘的逆冲而隆升,在凹陷中部形成NS向断层传播褶皱,在控陷断层下盘形成双重构造;在泉头组上段-嫩江组沉积时期为近NS向离散型走滑作用阶段,形成具有倾向滑移分量的走滑断层组合和负花状构造;在四方台组-新生界下部沉积时期为近EW向挤压作用阶段,使在早期控陷断层再次表现为上盘逆冲的特征,在断层上盘形成一大型反转背斜。松辽盆地伸展、挤压、走滑应力场的变化可能与太平洋板块的俯冲角度、方向和速率的变化有关。更多还原

【Abstract】 Fulongquan sag is of complex structural features and belongs to the second-order structural unit of the southeast uplift in Songliao basin,the first-order structural unit.Geological interpretation of seismic profile indicates that Fulongquan sag has undergone four stages since the Cretaceous:near EW extension begins from the deposition of Huoshiling Formation to the deposition of Yingcheng Formation,which forms NS trending half-garben and rollover structures controlled by a large scale dustpan-like,depression-controlling normal fault;near EW compression begins from the deposition of the Upper Member of Yingcheng Formation to the deposition of the Middle Member of Quantou Formation,leading to the thrust faults through the inversion of the early normal faults,further to the uplift of the west boundary of the sag,near the depression-controlling fault caused by the thrust of the hanging walls,and to the NS trending fault-propagation fold in the center of the sag and to the formation of the duplex in the foot wall of the depression-controlling fault;near NS trending divergent strike-slip extension starts from the deposition of the Upper Member of Quantou Formation to NenjiangFormation,forming the NS trending strike-slip faults with dip-slip component and negative flower structures;stage of near EW compression starts from the deposition of Sifangtai Formation to the deposition of the lower strata of Cenozoic,leading to the early depression-controlling fault with hanging wall thrust again and a large scale anticline in the hanging wall.The stress field changes of extension,compression,and strike-slip in Songliao basin may be related to the changes in the dip angle,direction and speed of the Pacific plate subduction.更多还原