关键词: 河套盆地, 兴隆构造带, 滑脱变形, 成因机制, 物理模拟

Abstract: The Xinglong structural belt is located in the northwest of Linhe depression in Hetao Basin. The exploration results of Well Hetan 101 with a daily oil production of 1000 tons prove that the structural belt has great potential for resource exploration. However, the poor understanding of the main controlling factors of the genesis of the oil and gas anticline structure impedes the implementation of the ultra-deep risk exploration well location deployment plan. Based on the refined interpretation of 3D seismic data in the study area, combined with the structural analysis, balanced section analysis and physical simulation of structures, this paper investigates the deformation characteristics and genetic mechanism of the detachment structure. The results show that： (1) The Xinglong tectonic belt experienced the evolution stages of compression depression, tension-shear fault depression and strike-slip transformation. The preexisting thrust faults of the basement formed in the compression stage control the initial development position of the detachment structure, and the spatial distribution characteristics of the gypsum rock layer control the development range of the cap rock detachment structure. (2) with the influence of pre-existing structure and sedimentary environment changes, salt lakes continued to migrate northward and shrink, resulting in significantly different spatial distribution characteristics of the gypsum rock detachment layer, which in turn leads to different structural styles of the detachment faults along the strike. (3) The detachment layer exerts a significant decoupling effect. The detachment layer causes a significantly different structural deformation pattern on and below the salt. The increase in the detachment layer thickness would enhance its decoupling effect. The enhanced decoupling effect reduces the number of detachment faults, increases the horizontal detachment distance, and increases the size of a single detachment system. In addition, secondary faults are developed near the main detachment fault and areas away from the main detachment fault, the. (4) Under the extension regime, the detachment transfer mode of progressive deformation with the main detachment fault to the front will occur above the ductile detachment layer, and the amplitude and size of anticline decrease in turn. When the tensile stress on both sides is equal and the thickness of the detachment layer is same, the transmission distance of the deformation fronts on both sides of the model tends to be consistent, showing characteristics of symmetrical deformation.

Key words: Hetao Basin, Xinglong Tectonic Belt, slip deformation, the formation mechanism, physical simulation