Seismic Structure Beneath Zagros-Makran Transition Zone (Iran) from Teleseismic Study: Seismological Evidence for Underthrusting and Buckling of the Arabian Plate Beneath Central Iran

Document Type : Seismology and Engineering Seismology

Authors

1 IIEES

2 Joseph Fourier University, Grenoble

Abstract

Receiver function analysis in transition zone between the Zagros collision zone and the Makran subduction zone shows gradual increment of the Moho depth to ~58km into the north. The Moho depth is ~32km beneath western end of the Makran prism (58º E-26.6ºN). Furthermore, crust thickening to ~58km is observed 60km west of the Zendan-Minab-Palami fault system (ZMP) that is unusual for this part of the Zagros. This implies deflection of the Arabian Platform west of the ZMP. The Moho upwarp under region of the Khurgu indicates that the mountain ranges were lifted enmasse as a result of crustal buckling under horizontal compression. Moho depth variation beneath other stations in eastern end of the Zagros is around ~45km and increases into north to ~53km beneath Main Zagros Thrust (MZT). Strong PS conversion is observed under Zendan-Minab-Palami fault system in upper crust that could be related to unconsolidated material associated with this fault. Inversion of P travel time residuals suggests a low velocity zone beneath the transition zone in accordance with the receiver function result. This information implies underthrusthing of the Arabian plate beneath the Central Iran and the gradual transition into thinner crust beneath the accretionary prism of the Makran.

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