The Characteristics Of The Western Extension Of The Karakax Fault In The West Kunlun And Its Tectonic Implications

The Karakax strike-slip fault,located in the northwest of the Tibet,is a long-lived evolution deformation belt,which is still active at present and play an important role in controlling the evolution of this area.Most geologists suggest that the Karakax fault is generally east-west striking along the Karakax river valley,and northwest striking until to the Tashkorgan in the Mazar area.However,via the detailed field geological survey,an ENE-WSW fault,which named as the Matar fault,is identified at the Mazar area.Based on the measuring geological sections?analyzing microscopic structures and CPO pattern?⁴⁰Ar-³⁹Ar dating,the similar geometry and kinematic characteristics were existed between the Karakax and Matar faults.Both the two faults have undergone the right-lateral and thrust ductile deformation in the early stage,and turned to left-lateral brittle deformation in the later stage.The Matar fault and the Karakax fault should belong to the same fault system,and the former is the westward extension of the latter.Both the two faults have undergone two stages of tectonic uplifting?120¹30Ma and²00Ma?,and adjusted together the tectonic deformation of the northwestern Tibetan Plateau caused by the plate collision since Mesozoic,and the geomorphology characteristics of the West Kunlun-Pamir area were formed by the strong activity of the Karakax fault and the Karakarum fault and so on in Cenozoic.