The Salt Diapirs of the Eastern Fars Province (Zagros, Iran): A Brief Outline of their Past and Present

Abstract

The salt diapirs of the eastern Fars (Zagros, Iran) have been reexamined in light of their relationships to the regional geodynamic history. The present-day surface morphology of salt diapirs can be divided into six types, which we suggest represent different stages in a long and complex history: type A are buried diapirs, type B high relief active diapirs, type C with salt fountain and glacier, type D similar to type C but with more erosion and with out fountain, type E as dead diapirs and empty crater, and type F linear diapirs generally emerging along faults. We show that nearly all the diapirs of the study area were already active prior to Zagros folding either as emergent diapirs forming islands in the Paleogene to Neogene sea or as buried domes initiated at least by the Permian. They have been reactivated by subsequent tectonic events. At the initiation of Zagros folding, the abundance of emergent diapirs close to the present Persian Gulf coast line weakened the entire sedimentary cover and facilitated the preferential localization of the deformation in a narrow zone. Then, salt-cored detachment folding in the whole eastern Fars Zagros Fold-Thrust Belt reactivated the preexisting domes and allowed salt movement along faults.