Late Oligocene Orogen‐Scale Tilting in Northern Tibet: A Response to Northward Injection of the Tibetan Lower Crust?

Abstract

Abstract The East Kunlun Shan (EKLS) in northern Tibet occupies boundaries of the low‐relief topography and lower crustal low‐velocity zone in the interior plateau, making it ideal for exploring the relationship of surface deformation with underlying geodynamic processes. We used previous and new apatite (U‐Th)/He data to analyze the exhumation history and pattern throughout the EKLS and link surface deformation to deep structures. Integrated (U‐Th)/He ages reveal the rapid exhumation at 27–25 Ma, due to the coeval orogen‐scale tilting of the EKLS. Along with the crustal structures beneath the EKLS, it is inferred that orogen‐scale tilting is the isostatic response of the nonuniform crustal thickening related to northward injection of the Tibetan lower crust. This study highlights the role of ductile deformation within the lower crust in mountain building in northern Tibet, which shares a similarity with mountain building pattern in the eastern plateau margin.

Keywords

• northern Tibet
• East Kunlun Shan
• apatite (U‐Th)/He
• orogen‐scale tilting
• late Oligocene
• isostatic response