大杨树盆地的构造特征及变形期次

大杨树盆地是叠置于大兴安岭造山带的东部,与松辽盆地紧邻,呈北北东向长条带状展布的中新生代断陷-坳陷型盆地。大杨树盆地经历了多期变形作用,具有以伸展构造为主、并被挤压构造和反转构造叠加的构造特征。早白垩世龙江期主要受到了NWW—SEE向的拉伸作用,形成一系列北北东向控陷犁式正断层组合,在控陷断层的上盘发育小型箕状断陷;早白垩世九峰山期,大杨树盆地受挤压作用控制,使早期形成的断陷盆地发生反转作用,形成正反转构造,同时在某些地段形成逆冲断层和断层传播褶皱;早白垩世甘河期,大杨树盆地再次受到伸展作用,形成了一系列北北东向小型断陷。早白垩世晚期(甘河期之后)—晚白垩世早期,大杨树盆地受到强烈的挤压作用,使早期控陷正断层出现正反转作用,在盆地的浅部形成大型断层传播褶皱,使大杨树盆地全面隆升遭受剥蚀。第四纪大杨树盆地具有伸展的特征,发育一系列小型伸展断陷。

Structural Features and Deformation Stages of the Dayangshu Basin in Northeast China

Dayangshu Basin is a Mesozoic-Cenozoic basin which is located on the east part of Daxing'anling orogenic belt.It is in a long narrow shape with the NNE trending and next to Songliao Basin to the east.Dayangshu Basin experienced multistage deformations,which is characterized mainly by extensional structures,and was superimposed by compressional structures and positive inversion structures.The basin was suffered NWW-SEE extension during Longjiang stage of the Early Cretaceous,a series of listric normal faults was formed,and the half-grabens were developed on the hanging wall of the controlling fault.Dayangshu Basin was controlled by NW-SE compression during Jiufeng-shan stage of the Early Cretaceous,the early faulted depressions were inversed by contraction to form inversion structures,and fault propagation folds and thrust faults were formed in some places.Dayangshu Basin was suffered extension again during Ganhe stage of the Early Cretaceous,a series of small NNE trending fault depressions formed.Dayangshu Basin was suffered intensive compression during late stage of the Early Cretaceous to early stage of the Late Cretaceous,and the early depression-controlling normal faults were inversed,and fault propagation folds formed on the upper part of the basin.The basin was raised completely and suffered erosion.Dayangshu Basin was in extensional setting in the Quaternary period,and a series of small extensional half-grabens were formed.