Crustal Shortening Mechanism Near the Central Altyn Tagh Fault in Northern Tibet

Abstract

The Altyn Tagh Fault, as the northern edge of the Tibetan Plateau, is crucial for understanding the plateau evolution and continental convergence processes. Using teleseismic waveforms recorded by a 300‐km‐long broadband seismic array deployed by our team in northern Tibet, we investigate the detailed crustal and upper mantle structure beneath the middle section of the Altyn Tagh Fault system and the eastern Kunlun Fault. Our receiver function results reveal complex intra‐crustal discontinuities and a laterally variable Moho beneath the study region. These features suggest a vertically partitioned shortening mode in northern Tibet. The upper crust accommodates horizontal shortening through brittle faulting and folding, whereas the mid‐lower crust responds through ductile deformation, distributed shear, and basal thickening. Along with lateral extrusion, far‐field compressional stresses from the India‐Asia collision and the blocking effect from the rigid Tarim Basin craton have contributed to the crustal shortening in the brittle middle section between the Altyn Tagh Fault and the eastern Kunlun Fault.