龙门山褶皱冲断带剥蚀-沉积作用和先存断层结构砂箱物理模拟OA

Fold-thrust foreland basin systems generally undergo a complex shallow tectonic denudation-deposition process that is controlled by factors such as rock stratum distribution and preexisting structure,imparting them with complex three-dimensional spatial structural deformation characteristics and evolutionary processes.In this paper,the Longmenshan fold-thrust belt in the western Sichuan foreland basin system,located on the eastern margin of the Qinghai-Tibet Plateau,is taken as the study object.Based on sandbox analog experiments,an experimental model with preexisting faults and weak rock strata as controlling factors was designed.The structural evolution sequence and subsidence history of different tectonic belts were analysed and discussed.The results show that erosion and sedimentation obviously leads to multistage activation of the boundary faults of the thrust belt,and the area around the preexisting faults is a structurally weak zone.During the compression process,preexisting faults are reactivated to accommodate inversion structures.The existence of a weak detachment layer leads to decollement,which in turn facilitates the formation of diverse inversion structures.The erosion and sedimentation histories of different tectonic belts in the fold thrust belt are significantly different.The hanging wall material of the thrust belt demonstrates a weak buried depth,arising from thrust deformation,and a rapid and continuous burial process occurred during the thrust load process of the foreland basin.The buried structural belt in the frontier of the Longmenshan Mountain has an inverted structural deformation zone that facilitates oil and gas accumulation.