Late Pliocene to Quaternary evolution of the Shotori strike-slip deformation belt: The interplay between thin- and thick-skinned tectonics along the border between the Tabas and Lut blocks, Iran

The indentation of the Arabian plate into the Eurasian plate, accommodated by strike-slip faults, resulted in the formation of the Shotori strike-slip deformation belt (SDB). The development of the SDB was related to the strike-slip movement along the Nayband fault separating the Tabas and Lut blocks of Iran, and accommodation of the counterclockwise rotation (CCW) of these blocks. We integrate field structural analysis, geomechanical modeling, potential field interpretation, the interpretation of the 16September 1978 Tabas earthquake sequence, and the structural model of the SDB to document the late Pliocene to present evolution of the SDB. The structural model reveals two domains: an upper thin-skinned fold belt (Tabas fold belt) and a lower thick-skinned thrust belt. The SDB provides a rare opportunity to examine the interplay between thin- and thick-skinned tectonics in an active transpressional setting. The performed studies allowed us to distinguish the late Pliocene to Quaternary contractional deformation stage when the simple shear component still dominated along the Nayband fault, but the amount of the shortening component increased significantly in comparison to the early Miocene to Pliocene stage of deformation affecting the Tabas block. This change was likely related to the CCW rotation of the Tabas and Lut blocks, which led to the westward pushing of the corner of the Tabas block by an indentation of the Lut block. The observed variation in σ1 tilting with depth, from ∼33° in the thick-skinned thrust belt to ∼0° in the thin-skinned fold belt, explains the formation of diverse active structures in the SDB.