Regional 3-D lithosphere structure of the northern half of Iran by local earthquake tomography

Abstract

SUMMARY The 3-D P-wave velocity structure of the northern half of Iran crust has been determined from the local earthquake tomography using a high-quality data set of semi-automatically re-picked arrival times. The quality and quantity of these re-picked phase data allow the 3-D imaging of large parts of the northern half of Iran lithosphere between 0 and 60 km depth. Our new P-wave tomography model represents a major improvement over existing models in terms of reliability, resolution and consistency. First-order anomalies such as the crustal roots of the Zagros and Alborz Mountains are clearly resolved. In addition, several shallow smaller-scale features like the Central Iran sedimentary basin and volcanic and igneous rocks are visible in the tomographic image. Our results show deep Moho depressions beneath the Central Alborz and Zagros mountain ranges that are part of the Arabia–Iranian–Eurasia continental collision zone and locally this Moho topography agrees very well with existing models of other studies. The observed P-wave velocity structure suggests that compared to the Sanandaj-Sirjan and Zagros mountain ranges there is a minor crustal thickening beneath the Alborz mountain range and Kopeh Dagh region.