The Zagros hinterland fold-and-thrust belt in-sequence thrusting, Iran

•This study introduces a second fold-and-thrust belt on the NE side of the Zagros orogenic core.•Studies indicate that the component of sub-simple shear deformation, αe = 23.4° ± 9.1°.•Faulting and folding are linked kinematically in this hinterland fold-and-thrust belt.•The formation of duplex systems, FBFs and FPFs are the consequences of in-sequence thrusting.•A lateral ramp in the involved-basement between two constructed cross sections is introduced.

The collision of the Iranian microcontinent with the Afro-Arabian continent resulted in the deformation of the Zagros orogenic belt. The foreland of this belt in the Persian Gulf and Arabian platform has been investigated for its petroleum and gas resource potentials, but the Zagros hinterland is poorly investigated and our knowledge about its deformation is much less than other parts of this orogen. Therefore, this work presents a new geological map, stratigraphic column and two detailed geological cross sections. This study indicates the presence of a hinterland fold-and-thrust belt on northeastern side of the Zagros orogenic core that consists of in-sequence thrusting and basement involvement in this important part of the Zagros hinterland. The in-sequence thrusting resulted in first- and second-order duplex systems, Mode I fault-bend folding, fault-propagation folding and asymmetric detachment folding which indicate close relationships between folding and thrusting. Study of fault-bend folds shows that layer-parallel simple shear has the same role in the southeastern and northwestern parts of the study area (αe = 23.4 ± 9.1°). A major lateral ramp in the basement beneath the Talaee plain with about one kilometer of vertical offset formed parallel to the SW movement direction and perpendicular to the major folding and thrusting.

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