Melt‐Regulated Crustal Kinematics in the Pamir, NW Tibetan Plateau: Insights From Surface‐Wave Tomography

Abstract The Pamir, located at the northwestern margin of the Tibetan Plateau, is undergoing E–W extension within its interior, accommodated by micro‐block motions along major fault systems; however, the mechanisms governing this modern block kinematics remain elusive. Here, we present an updated crustal shear‐wave velocity model of the region, developed via adjoint‐state surface‐wave traveltime tomography. The Rayleigh‐wave dispersion data set is compiled from teleseismic and regional earthquakes, as well as ambient noise; for the latter, three‐station interferometry was employed to incorporate asynchronous records. The resulting model reveals distinct middle‐to‐lower crustal low‐velocity zones (LVZs) that spatially align with the major active faults bounding the micro‐blocks. Although the estimated melt fractions within these LVZs fall below the rheological threshold required to sustain large‐scale flow, rock strength is drastically reduced within these zones. This melt‐induced weakening focuses deep‐seated strain and promotes fault development, thereby regulating the modern crustal kinematics of the Pamir.