The structure features of the fold-thrust belts in the western margin of Ordos Basin and the north margin of Tarim Basin can be classified into 11 types: 1. Fold-thrust type in the Gangder mountain and Kasangtouk anticlinal belts; 2. Fold-thrust and nappe type in the Xiaosong Mountains and north of Luntai area; 3. High angle thrust-drag fold type in the Hengshanbao and Kalpin region; 4. Listric thrust-nappe type in the Luo ShanMajiatan region; 5. Syndepositional basement thrust type in the Tiekesumiao and Sajinziarea; 6. Basement wedge thrust type in the Taolou and Xinhe region; 7. Basement back thrus type in the Luntai area; 8. Reversed thrust type

for example

Xilaifeng and north Wensu faults; 9. Basement wrench-thrust type

for example

Agia

Yingan and Zhenyiguan faults; 10. Basement wrench-fault type

for example

Kalayurgun fault;11. Surface wrench-fault type. The study area has the characteristics and evolution history of foreland basin. The fold-thrust structural be1ts in the basin have four kinds of formation mechanism: 1. Lateral compressive stress between the Ordos and Alashan terrains and between the Tarim and Junggar microplates; 2. Basement shorterning based on the prior-batheent detuchment; 3. Basement ramp with Luoshan-Majiatan listric thrusts as typification; 4. Surface decollement with Qiuritak anticlinal belt as typification.