干旱区生态环境知识资源中心

Ambient noise tomography is used to retrieve Rayleigh wave group and phase velocity variations in the period range of 8-40 s based on the vertical component of cross-correlation functions from permanent broad-band and mid-band seismometers across the Iranian Plateau. The iterative, non-linear inversion method of fast marching surface tomography (FMST) is employed to produce 2-D group and phase velocity maps. Shear wave velocities are also estimated using a linear least-square method.

Unlike most previous largescale tomographic results, our group, phase and shear wave velocity estimations, emphasize low velocity crustal structure (up to 50 km depth) beneath Zagros Fold and Thrust Belt (ZFTB) and Sanandaj-Sirjan metaphormic Zone (SSZ). The suture zone resulting from the subduction of the Arabian plate under the Central Iran is inferred along the boundary of SSZ and Urmieh-Dokhtar Magmatic Arc (UDMA). The velocity patterns show the main sedimentary basins, and reveal lateral velocity changes indicating the crustal thickening beneath ZFTB, SSZ and Lut Desert (LD), and the crustal thinning beneath Kavir Desert (KD) and UDMA are well inferred. A prominent low velocity is persistent in the whole crust beneath the central part of Alborz mountain range with high topography, and we suggest that it is likely due to elevated crustal temperatures within thin lithosphere.