Lithospheric Structure of the Makran Subduction Zone and Central Asian Microcontinents Based on Surface Wave Analysis

The Zagros–Himalaya collision zone is among the most active and structurally complex convergent boundaries on Earth, making it a critical region for investigating plate tectonics, mountain-building processes, and seismic hazards. Despite substantial research on segments of this belt, significant gaps persist, particularly in understudied areas such as the Makran subduction zone and Central Asian microcontinents. In this study, we developed a high-resolution 3D shear-wave velocity (V_s) model to investigate the lithospheric structure of the Makran subduction zone and Central Asia. We analyzed fundamental-mode Rayleigh wave group velocity dispersion curves from regional earthquakes within the period range of 6.5–80 s. Variations in velocity gradients across the V_s model enabled the estimation of spatial changes in key lithospheric discontinuities, including the sediment–basement interface and the Moho depth. The thickest sedimentary layer (15–20 km) occurs in the Makran Accretionary Wedge. Additional thick basins (>10 km) include the Jazmurian and Mashkel Depressions, the Amu Darya-Tajik Basin, and the southwestern Helmand Block. The thinnest continental crust (35–40 km) occurs beneath the Lut and Helmand Blocks that are surrounded by thicker, highly deformed crust (50–65 km) in the Zagros Collisional Belt and the Hindu Kush Mountains. The oceanic Moho depth beneath the Arabian Plate, within the Makran Accretionary Wedge, ranges from 20 to 30 km. The subduction angle of the Arabian slab steepens beneath the southern margins of the Jazmurian and Mashkel Depressions, reaching depths greater than 60 km beneath the Bazman–Sultan Volcanic Arc. Dominant low-V_s anomalies in the Hindu Kush and Central Asian regions indicate uppermost mantle deformation resulting from the ongoing convergence between the Arabian, Indian, and Eurasian Plates.