Abstract: The structural model and structural formation mechanism of Karaza-Gumudi complex structures in southern margin of Junggar basin are analyzed by applying folded theory related to foreland basin. Karaza-Gumudi area is subjected to the effects of asymmetric north Tianshan Mountain, Bogda and Aika shove fault systems, being dominated by shear and compresso-shear actions. Karaza anticline belongs to dual structure with shallow reversed thrust; Gumudi anticline to dual structure with basement-involved style. Qigu-Changji anticline belt in west of piedmont thrust zone and Gumudi-Fukang anticline belt in east of it were resulted from adjustment and transform of Karaza reversed fault. Asymmetric Changji syncline was formed by asymmetric action in Bogda shove fault, forming the largest and deepest subsiding center followed by a typical complex petroleum system. Karaza anticline and Gumudi anticline as two types of structural styles are major targets for hydrocarbon prospecting in the near future.

Key words: Junggar basin, Karaza, Gumudi, structure, structural type, mechanism