Deformation Characteristics And Dynamic Mechanism Of The Abdominal Structural Zone In The Qaidam Basin

The Abdominal Structural Zone is an important oil-gas distribution area in the Qaidam Basin.Due to the poor quality of seismic data and the harsh natural environment,there is still a lot of controversy about the geological structure of this area.Based on surface geology,seismic and drilling date,this paper studied the deformation characteristics,evolution process and dynamic mechanism of the three structural Zone including Qianfu,Lenghu and Eboliang Structural Zone.It is significant for oil and gas exploration in this area.The Abdominal Structural Zone has the deformation characteristics of east-west zoning and upper-lower stratification.The Qianfu Structural Zone is characterized by imbricated thrust deformation,which is controlled by the uplift and thrust of Qilian Shan.The shallow structures of the Lenghu and Eboliang Structural Zone show fault propagation folds,while the deep ones are a series of reverse faults and their combination,which were reformed by dextral strike-slip deformation in the late stage.According to the growth strata and stratigraphic flattening,the deformation process of the Abdominal Structural Zone can be divided into three stages: 1)Yanshanian extensional deformation,the development of a series of normal faults;2)the remote effect of the initial collision between India and Eurasia in the early Cenozoic led to thrust deformation in the Qilian Shan and the abdominal region,and the Yanshanian pre-existing normal faults in the Lenghu and Eboliang regions started to move,than the Qianfu Structural Zone and the Lenghu and Eboliang Structural Zone developed.3)The uplift and expansion of the Tibetan Plateau produced oblique compressional stress in the Abdomen area in Late Cenozoic,which caused right lateral strike-slip deformation and positive flower structures in the deep structures.At the same time,en echelon normal faults was developed on surface.