Research Of Structural Characteristics And Genetic Mechanism Of The Changyuanba Structural Belt In Southern Sichuan

The south Sichuan is located at the southern edge of Sichuan basin.It is a secondary tectonic unit of the high-steep fold area in East Sichuan Basin,which is the extension of Huaying Mountain Fault Zone to the southwest.Due to the limitation of the north-south,east-west and north east-southwest direction's boundary faults,the whole form is scattered like a broom to the southwest,which is a extremely intricate area of tectonic environment.Based on the analysis of two-dimensional seismic profile interpretation and drilling data,this paper studies the structural characteristics,formation and evolution of Changyuanba by combining with the balanced section technique,and it is based on the idea of the mechanism of the construction of the barrier,which is the result of the analysis of the physics simulation.The study has obtained the understanding of the actual regional tectonic deformation characteristics.The results are as follows:(1)A detailed study of the surface and subsurface structures in the study area is made.It is recognized that the slipping layer of the lower Cambrian Niutitang formation in the Cambrian formation and the Lower Silurian Long Maxi formation is divided into three sets of upper,middle and lower strata,of which the lower deformation layer under the Cambrian system is weak,the fault is not developed,and the Cambrian system is to the Cambrian system.The middle deformable layer of the Silurian system.The deformation is strong,the faults are more developed,and they are all reverse faults.The upper deformation layer of the Permian and upper strata are stable and mostly fold deformation.(2)According to the balance section recovery method,the shortening of the study area is calculated and the position of the detachment layer in the study area is determined.Combining the deep feature interpretation of the study area and the LandMark stratigraphic analysis,it is believed that the Changyuanba tectonic belt was early in the two and the Triassic period and was affected by the paleo uplift of the northern Luzhou,and the slipping layer along the lower Cambrian Niu Titang formation.Gravity decollement formed,forming a rudiment of South to steep north.Accordingly,the formation period of the Changyuanba structural belt has been reclassified.It is considered that the structural belt of the Changyuanba has undergone three tectonic movements.The Permian and Triassic period,influenced by the Luzhou paleo uplift in the northern part of the north to the south,produced gravity slipping from north to south,forming the rudiment of the fold of the Changyuanba structural belt.During the Yanshan period,the early tectonic deformation was more intense due to the extrusion of the mid Guizhou Uplift from the south to the north.The Himalayan period,subjected to the near E-W extrusion of the Xuefeng mountain uplift in the Southeastern part of the basin,made the Changyuan ba structure,which was originally E-W,superimposed the North and South structures,and formed the present tectonic form of the study area.(3)According to the principle of similarity,we design the physical modeling experiment in the study area.The results show that under the Permian geological environment,under the sole force source of the paleo uplift of the northern Luzhou,the strata along the lower Cambrian Niu Titang formation slipping formation gravity slipped into the slow South and steep asymmetric folds,which proved that the Changyuanba tectonic belt was first affected by the ancient uplift of Luzhou and along the lower Cambrian Niu Titang formation.The possibility of forming a fold in a group of gravity slips.