Interpretation of structure of lithosphere and crust in Zagros region using modeling of topography, geoid, and potential field data (gravity and magnetic)

We apply two forward methodologies in order to study density and susceptibility structure of the crust and upper mantle. The study area is a profile crossing the Zagros collision zone located as margin of Eurasia-Arabia converging plates. Gravity modeling focusing on lithospheric structure is performed in thermodynamic framework in which chemical composition is important and provides an understanding of deep layers in lithosphere like Moho and Lithosphere-Asthenosphere Boundary. Results on the crustal thickness show minimum values beneath the Arabia Platform and Central Iran (42–43 km), and maximum values beneath the Sanandaj Sirjan zone (SSZ; 55–63 km). Results on the lithosphere thickness a long profile also indicate that the Arabian lithosphere is approximately 220 km thick, toward North West of Iran especially below the Central Iran rises up to 90 km. In the profile (central Zagros), lithosphere thinning occurs in wider region, from the Zagros fold thrust belt to the Sanandaj Sirjan zone. Our results are based on application of average Proterozoic mantle compositions in modeling beneath the Arabian Platform, Mesopotamian Foreland Basin and Iranian Plateau. After rough estimation of upper crust via integrated modeling by elevation, gravity and geoid data, the distribution of density and magnetic susceptibility values allows us to perform a study in crustal scale. Afterwards, determination of the homogenous blocks with the same density and susceptibility, the geometry to different crustal layers including sediments, upper, middle and lower crust deep to Moho boundary were refined in crust-scale study based on regional model in lithospheric scale. Presence of Main Zagros Fault is a bold point in our modeling which leads to better fit of gravity data.