Deformation of Chuxiong Foreland Basin

Locating in the southwestern margin of the Yangtze Plate,the Chuxiong Basin in Yunnan Province is a Mesozoic foreland basin formed in the northeast of the Ailaoshan-Honghe Collisional Orogenic Belt after the closing of the Jinshajiang-Mojiang Oceans of Paleo-Tethys during the Middle Triassic.The basin has experienced 2 stages of tectonic deformations.In stage Ⅰ,from the Late Cretaceous to Eocene,the Ailaoshan-Honghe Collisional Orogenic Belt uplifted and thrusted from south to north to the Chuxiong Foreland Basin,resulting in progressive inversion and fold deformation belt with decreasing deformation strength as well as sinistral strike-slip fault by the side of nappe.In stage Ⅱ,from the end of Oligocene to Miocene,as the Indian Plate collided with the Eurasian Plate and kept wedging and squeezing,the axial of the Chuxiong Basin changed from EW to NW;meanwhile,fracture deformations such as right-lateral movement and simple shear took place,and the thrust-fold deformation from SW to NE happened.