The Yadu—Ziyun fault zone is a significant regional- scale intracontinental high- strain zone along the southwestern margin of the Yangtze Block. However, its deformation characteristics, tectonic attributes, and evolutionary history remain highly controversial, which has constrained our understanding of the regional tectonic evolution and structural framework of the southwestern South China Block.Methods: Detailed field geological investigations, stratigraphic section measurement, and paleostress analyses focused on structural geology were conducted along different segments of the Yadu—Ziyun fault zone.Results: The northwestern segment is characterized by high- angle reverse faults distributed along anticlinal cores, which resulted from continued compressional deformation during the Early—Middle Triassic Indosinian orogeny. This process drove the upward migration of neutral surfaces in fault- related folds and led to thrust faulting developed in the vicinity of tightly folded anticlinal cores. In contrast, the southwestern segment lacks prominent fault distribution but exhibits M- or W- shaped folds, indicating distinct strain heterogeneity. These findings support the interpretation that the Yadu—Ziyun fault zone is a high- strain deformation belt consisting of NW—SE- trending reverse faults and folds.Conclusions: The Yadu—Ziyun fault zone is not the northeastern boundary of the Nanpanjiang Basin, but rather an important regional elongated extensional rift zone along the northeastern margin of the basin that formed during the Late Paleozoic. It records NE—SW- directed thrusting and folding events during the Indosinian period and subsequent near E—W- directed compressional sinistral strike- slip deformation during the Yanshanian period. The superposition of Indosinian and Yanshanian tectonic events in the adjacent areas of the Yadu—Ziyun fault zone is manifested as typical dome- and- basin structures.