Tectonic evolution of the Ailaoshan–Red River shear zone and its relationship with the growth of the southeastern Tibetan Plateau

Abstract

The Ailaoshan–Red River shear zone (ARSZ), which is ∼ 1000 km long and one of the largest boundary strike-slip fault zones in the southeastern margin of the Tibetan Plateau, provides valuable insights into the growth process of the southeastern Tibetan Plateau since the India-Asia collision. During the Late Miocene to Early Pliocene, the ARSZ underwent a kinematic transition from left-lateral strike-slip to right-lateral strike-slip motion. To reveal the mechanism of this kinematic transition and its relationship with the growth process of the southeastern Tibetan Plateau during the Cenozoic, we conducted paleomagnetic and tectonic deformation analyses on both sides of the ARSZ. The results show that the formation of the S-shaped bending and kinematic transition of the ARSZ were controlled by the changes in clockwise rotation rates of the Chuandian Fragment and the Indochina Block. This suggests that since the Oligocene, the growth of the southeastern Tibetan Plateau progressively extended outward from the southern margin of the Lhasa Terrane to the southeastern margin of the Tibetan Plateau, resulting in the sequential initiation of the clockwise rotation of the Shan-Thai Block, Indochina Block, and Chuandian Fragment since the Late Oligocene, and in variations in the rotational rates of these blocks. The different rotational movement of these blocks controlled the tectonic evolution of strike-slip fault systems on the southeastern margin of the Tibetan Plateau.