The dynamics of Mesozoic intraplate deformation within the South China block and its association with plate-margin orogenesis have long been debated. To address this issue, we conducted detailed structural mapping and zircon U-Pb dating in the Youjiang tectonic belt of the South China block. The results indicate four phases of deformation (D₁？D₄) that produced three standard types and 10 subtypes of superimposed folds. D₁ is characterized by top-to-the-W thrusting at 244？237 Ma. D₂ is divided into D₂¹, D₂², and D₂³. D₂¹ comprises top-to-the-NE thrusting at 237？218 Ma, D₂² generated top-to-the-SW back-thrusting ca. 218 Ma, and D₂³ is characterized by top-to-the-NE thrusting at 218？187 Ma. D₂² overprinted D₁ with an angle of ～60° between f₁ fold axes and the maximum principal compressive stress P₂², resulting in type 1d, 1e, and 1f superimposed folds. D₂³ overprinted D₁ with an angle of ～30° between f₁ and P₂³, resulting in type 2a superimposed folds. The different types of superimposed folds can be distinguished by the angle between the early fold axes (f_e) and the orientation of the subsequent maximum principal compressive stress (P_l). D₃ is characterized by top-to-the-NW thrusting at 175？127 Ma. D₃ overprinted D₁ and D₂ folds, forming type 1a, 1b, and 1c or type 2a and 2b superimposed folds, depending on the geometry of the earlier folds. D₄ is characterized by NE-trending normal faults that formed at 93？82 Ma. Changes in kinematics and the types of superimposed folds were related to clockwise rotations of the South China block by ～30° and ～5°？10° during the Triassic and Jurassic？Early Cretaceous, respectively. Intraplate deformation in the Youjiang tectonic belt was generated by progressive propagation of the foreland fold-and-thrust belt during Triassic collision of the South China block and Indochina, and selective reactivation of the Jiangshan-Shaoxing suture zone along the existing weak tectonic belt during Jurassic？Cretaceous subduction of the Paleo-Pacific plate. The superimposed folds of the Youjiang tectonic belt were formed as a result of clockwise rotation of the South China block from the Triassic to Cretaceous.

Article link: https://doi.org/10.1130/B38436.1