Underplating along the northern portion of the Zagros suture zone, Iran v23

A 2-D absolute shear wave velocity model has been resolved beneath a seismic profile across the northeastern margin of the Arabian Plate-Central Iran by simultaneously inverting data from P receiver functions and fundamental mode Rayleigh wave phase velocity. The data were gathered by a linear seismic array crossing the Zagros fold and thrust belt, Urmia-Dokhtar magmatic arc and Central Iran block assemblage as three major structural components of the Arabia-Eurasia collision. Our model shows a low-velocity tongue protruding from upper to lower crust which, north of the Zagros suture, indicates the signature of an intracontinent low-strength shear zone between the underthrusting and overriding continents. The velocity model confirms the presence of a significant crustal root as well as a thick high-velocity lithosphere in footwall of the suture, continuing northwards beneath the overriding continent for at least 200 km. These features are interpreted as underthrusting of Arabia beneath Central Iran. Time to depth migration of P receiver functions reveals an intracrustal flat interface at similar to 17 km depth south of the suture; we interpret it as a significant decoupling within the upper crust. All these crustal scale structural features coherently explain different styles and kinematics of deformation in northern Zagros (Lorestan zone) with respect to its southern part (Fars zone).