Discrimination of Crust and Mantle Deformation from Differential SKS-Ps Splitting Analysis, Iranian Plateau

Аннотация

We present a new technique for shear wave splitting analysis in anisotropic mantle by combining the splitting analysis of Ps phases in receiver functions and SKS splitting analysis. Ps converted phases reveal evident variations in the effective arrival time as a function of back-azimuth in the anisotropic layer. This variation can be used to stacking to obtain the fast polarization direction and split time for an anisotropic layer. Our method was applied to data collected from the Iranian broadband permanent stations. Using teleseismic data, from 2004 to 2008, with magnitudes greater than 5.5 recorded at 14 permanent stations, we attempted to study crustal anisotropy beneath the stations. Then, we combined our results of the crustal anisotropy obtained from the receiver function analysis with the results of the SKS analysis to discrimination of crust and mantle deformation. The fast directions were parallel to the suture zone in the mantle beneath lower boundary of Central Iran micro-plate. The fast direction was almost parallel to the Alborz Mountain zone and perpendicular to the Zagros orogenic belt. Assuming that the fast polarization direction in the mantle is parallel to mantle flow, our investigation reveals the occurrence of horizontal melt flow which causes movement of the Arabic plate towards the Central Iran micro-plate.