Underthrusting of Tarim Lower Crust Beneath the Tibetan Plateau Revealed by Receiver Function Imaging

Abstract

The left-lateral Altyn Tagh Fault (ATF) system is the northern boundary of the Tibetan Plateau resulted from the India–Eurasia continental collision. How intracontinental deformation across the central ATF responds to the distal collision remains elusive, primarily due to unclear crustal structure. We obtained detailed crustal structure across the central ATF using receiver functions recorded by ∼NW–SE oriented linear dense array. The images reveal the Tarim lower crust is underthrusting beneath the Tibetan Plateau and reaches to a maximum depth of ∼75 km and undergoing partial eclogitization. The two south-dipping interfaces imaged beneath the Altyn Tagh Range (ATR) represent the thrusting Northern Altyn Fault and its branch fault. Oblique convergent forces extruded upper crustal materials along the thrust faults, creating the pop-up structure of ATR, supported by low Vp/Vs ratios. Our balanced cross-section for the Moho suggests intracontinental deformation in the ATR has accelerated since the late Miocene.