Abstract:
The Zagros orogenic belt, located at the leading edge of the collision between the Arabian Plate and Eurasia, is a typical region for studying continental collision and plateau growth. In this paper, we systematically compile the results of receiver functions, ambient noise tomography, body-wave tomography, magnetotellurics, and seismic attenuation imaging carried out in this study area, and conduct a multi-method comparison focusing on four issues: heterogeneous crustal thickening, middle–lower crustal weakening, crust–mantle decoupling, and lithospheric subduction–delamination. The results show that south of the Main Zagros Thrust, the Moho depth increases stepwise from approximately 40–45 km in the Arabian foreland to approximately 56–69 km in the Central Zagros. Receiver functions, surface waves, and tomography yield generally consistent images of the overall morphology, but the depth variations and lateral extents along strike exhibit notable segmentation. In the transition zone between the Zagros Fold-and-Thrust Belt and the Sanandaj–Sirjan Zone, the middle–lower crust simultaneously exhibits low seismic velocities, positive radial anisotropy, and high conductivity anomalies, mainly in the depth range of ~20–50 km. These anomalies partially overlap in space, indicating the presence of a ductile shear weakening layer involving fluids or partial melts. In contrast, the shallow low-velocity anomalies at 0–10 km depth are mainly controlled by thick sedimentary cover and salt detachment, and thus the subsurface properties reflected by the two sets of anomalies are not entirely consistent. The reversal of radial anisotropy polarity near the Moho and changes in electrical interfaces reflect rheological layering across the crust–mantle boundary. Body-wave velocities and Pn-wave attenuation images further reveal along-strike segmentation of the Arabian lithospheric subduction front: in the northwest and southeast segments, slab breakoff followed by rebound, underplating, and asthenospheric upwelling may have occurred. Strong Lg-wave attenuation constrains a relatively high crustal thermal state in the Zagros and adjacent areas. Existing models still have controversies regarding the nature of the low-velocity, high-conductivity materials, the characteristics of deep high-velocity bodies, and slab continuity. Future work requires dense array observations, joint inversions of velocity, attenuation, electrical conductivity, and density, combined with petrophysical experiments and three-dimensional thermal–rheological dynamic modeling.