Through 2D and 3D seismic interpretation and application of balanced cross section technique

basement structure

and tectonic characteristics and its evolution of the Mesozoic-Paleozoic of Jiaoshiba area

the Sichuan Basin are analyzed in this study.The results show that there are two types of structures in the study area.The first type is basement-involved structure

which is characterized by five structural patterns and assemblages

including back thrust anticlines

ramp syncline

imbricate thrusting

positive flower wrench and "多"-shaped wrench.The other type is cap detachment structure

which is characterized by five structural patterns and assemblages

including fault-propagation or fault-bend

fault-slipping

imbricate thrusting

imbricate ramp and thrust wedge.Additionally

the Early and Middle Yanshanian period are two major tectonic deformation periods.During the Early Yanshanian period

the nearly horizontal westwards detachment and decollement-nappe structures occurred along the interface between the Mesozoic-Paleozoic and the basement and the interfaces within the basement

resulting in the anticline-syncline alternating Zhuluoshan fold.The Jiaoshiba area between Fangdoushan fault and Datianchi anticline is within a broad compressional synclinorium structural background.During the Middle Yanshanian period

the detachment of the middle-deep burial basement in the eastern trough-like fold belt caused intensive westward thrusting

and then led to the formation of the tectonic framework of obduction-thrust-overthrust in the Jiaoshiba area.The double-layer back-thrusting anticline and faulted fold belt in the flanks were formed in Jiaoshiba area after three deformation episodes

including basement-involved imbricate thrusting-cap rock decollement-left-lateral transpression.Furthermore

Shimen faulted fold belt is characterized by multi-layer detachment folding structure and Wujiang fault-fold belt is characterized by detachment and left-lateral transpression structure.The tectonic deformation properties and types

decollement degree of the Longmaxi and Wufeng Formations

and layer-slipping structural fractures are the major tectonic factors controlling the shale gas play.