Cenozoic episodic uplift and kinematic evolution between the Pamir and Southwestern Tien Shan

Abstract

The Pamir Salient and Southwestern Tien Shan belong to two different systems, which collided due to the continuous northward drift of the Indian Plate during the Cenozoic, resulting in a shortening of ~300km. The uplift history and kinematic evolution of the Pamir-Southwestern Tien Shan remain unclear. In this study, we chose the 2025 m-thick Pakabulake formation in the East Wuqia section, at the southern-most margin of the Southwestern Tien Shan system, to obtain a high-resolution magnetostratigraphic record spanning ~16.61Ma to ~9.78Ma. Based on its high sedimentation rate, stable ca. E-W paleocurrents and stable magnetic susceptibility values, the nearby Southwestern Tien Shan was inferred to have undergone stable uplift during this period of sedimentation. Combining our results with the previous low-temperature thermochronology, magnetostratigraphy and re-calculated block rotations, we conclude that four episodic uplift events occurred in the Pamir-Southwestern Tien Shan during the Cenozoic, at times of ~50–40Ma, ~35–16Ma, ~11–7Ma and <5Ma, and that the first episodic uplift only occurred in the Pamir Salient. In addition, the Pamir Salient underwent a tectonic transformation from entire- to a half-oroclinal bending rotation during the Miocene, caused by activity along the Karakorum Fault and Kashgar-Yecheng Transfer System.