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

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[分类号] P542+.2 [文献标志码］A

Abstract： Fold-thrust foreland basin systems generally undergo a complex shalow 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 characteristicsand evolutionary processes.In this paper，the Longmenshan fold-thrustbelt in the western Sichuan foreland basin system，located on the eastern marginof the Qinghai-Tibet Plateau，is taken as the study object. Based onsandbox 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 beltswere analysed and discussed.The resultsshow that erosion and sedimentationobviouslyleads to multistageactivation ofthe boundaryfaults of thethrust 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 inthefold thrustbeltare significantlydifferent.The hanging wallmaterialof the thrustbelt demonstratesa weak buried depth，arising from thrust deformation，and a rapid and continuous burial process occurred during the thrust load processof the foreland basin.Theburied structural beltin the frontierof theLongmenshanMountain hasan inverted structural deformation Zone that facilitates oil and gas accumulation.

Key words：fold-thrust belt；eastern margin of the Tibetan Plateau；erosion and sedimentation；preexisting fault；inversion structure； subsidence history

褶皱冲断带形成演化普遍伴随大规模褶皱冲断与抬升剥蚀作用，导致地壳缩短增厚和前陆盆地挠曲沉降，其构造抬升剥蚀-沉积沉降耦合机制控制着褶皱冲断带-前陆盆地系统构造变形样式和演化过程（Mugnier etal.，1997;Fillon et al.，2013；Butler，2020；邓宾等，2021），如褶皱冲断和抬升剥蚀作用导致的断层多期活化与构造反转、沉积作用导致的断层活动停滞和低角度断层滑脱扩展等。（剩余27242字）