Paleozoic Salt Ridges and Diapirs, an Alternative to Basement Faults in the Structural Evolution of the Southern Zagros

The Zagros Fold and Thrust Belt and its foreland, the Persian Gulf form a prolific province for exploration and production. In the south Zagros folded Belt where a thick Eocambrian salt deposited (Hormuz salt) the present-day regular distribution of salt diapirs was interpreted to be related to reactivated basement faults located below the diapirs. This work is based on a general survey of the whole southern Zagros where salt diapirs are exposed, as well as interpretation of onshore and offshore seismic. It shows that in this area, nearly all the diapirs developed before the Zagros folding, either as emergent diapirs forming islands in the Neogene Sea or as buried domes formed at least in late Palaeozoic. Salt-cored detachment folds and thrusts developed in the Zagros Fold-Thrust Belt during the Neogene, triggering the reactivation of pre-existing salt ridges or domes. Analogue sandbox experiments have been designed to investigate the parameters controlling the role of existing domes and salt ridges on Zagros folding. The models demonstrated that Palaeozoic Hormuz salt ridges and diapir patterns, can explain present-day salt extrusions and fold patterns, with or without basement faults reactivation.