Crustal thickness variations in Zagros and Alborz collision zones by using P receiver function technique

Continental convergence between Arabia and Eurasia is taken up by distributed deformation in Alborz and Zagros collision zones in Iran. We applied P receiver function method to image the variations geometry of the crust–mantle boundary in two major mountain belts of the Alborz and Zagros in Iranian plateau. We used data from 65 seismic stations, which consists of 50 seismic stations of Institute of Geophysics, University of Tehran (IGUT), and 15 broadband stations of International Institute of Earthquake Engineering and Seismology (IIEES). Our results indicate that the average crustal thickness beneath central Iran domain (CD) is about ~48 km. The crustal thickness in this region varies between ~34 km beneath CHK station and ~55 km beneath IL3 station. We have found the Moho depth of about 45 km beneath the Zagros fold and thrust belt (ZFTB). Toward SE in ZFTB, we observe an increase in the Moho depth where it reaches ~59 km beneath BNDS and BNB stations. Crustal thickening (~54 km) has been observed beneath the central Alborz. We have also found strong thinning of the crust under the southern margin of Caspian Sea from ~33 km below KIA station to ~43 km below PRN station. Our data show a strong crustal thickening beneath the Sanandaj-Sirjan metamorphic zone (SSZ), with variations of ~53-66 km beneath BZA and KHMZ stations, respectively. Across the Urumieh–Dokhtar magmatic assemblage (UDMA), the crustal thickness varies between ~32 km below MEH station to ~62 km beneath CHMN station.