loading page

Two phases of shortening across northeastern Tibet as a result of a strong Qaidam lithosphere during the Cenozoic India-Asia collision
  • +4
  • Renxian Xie,
  • Lin Chen,
  • An Yin,
  • Xiong Xiong,
  • Yongshun John Chen,
  • Zhen Guo,
  • Kai Wang
Renxian Xie
Southern University of Science and Technology, Southern University of Science and Technology

Corresponding Author:[email protected]

Author Profile
Lin Chen
Institute of Geology and Geophysics, Institute of Geology and Geophysics
Author Profile
An Yin
University of California,Los Angeles, University of California,Los Angeles
Author Profile
Xiong Xiong
China University of Geosciences, China University of Geosciences
Author Profile
Yongshun John Chen
Southern University of Science and Technology, Southern University of Science and Technology
Author Profile
Zhen Guo
Southern University of Science and Technology, Southern University of Science and Technology
Author Profile
Kai Wang
Innovation Academy for Precision Measurement Science and Technology, Innovation Academy for Precision Measurement Science and Technology
Author Profile

Abstract

Current geologic observations support two contrasting views on the evolution of the northeastern Tibet north of the Qaidam basin: (1) crustal shortening started at the onset of the India-Asia collision about 50-60 Ma, and (2) crustal shortening did not start until after 20-15 Ma. To reconcile these two seemingly contradicting views supported both by observations, we perform a series of 2-D thermo-mechanical simulations with the goal of assessing the role of the lithospheric structure and strength of the Qaidam basin in controlling the Tibet deformation history. Our simulations yield three end-member scenarios for the first-order Tibetan lithospheric deformaiton: (1) mantle-lithosphere de-lamination in central Tibet accompanied by a deformation-free northern Tibet margin; (2) northward motion and deformation of southern Tibet accompanied by the southward subduction of the Asian lithosphere below northern Tibet, and (3) northward motion and deformation of southern Tibet accompanied by a deformation-free northern Tibet margin. Due to strong crust-mantle coupling of the Qiadam lithosphere, we suggest that the Tibetan lithospheric deformation is accorded with the third scenario. Our model results also show that the pre-existing weaknesses in northeastern Tibet is activated shortly after the onset of the India-Asia collision. This deformation field stays stable until after the removal of the mantle lithosphere in central Tibet, during which a second wave of northward propagating shortening sweeps across northern Tibet north of the Qaidam basin. This result is consistent with the existing data and reconcile the two end-member views on the tectonic history of the northern Tibet.