Detachment folding in the Central and Eastern Zagros fold-belt (Iran): salt mobility, multiple detachments and late basement control

Detachment folding has been studied on the basis of field and subsurface examples from the Central and Eastern Zagros (Iran). We discuss different aspects of detachment folding well illustrated in the studied area. In particular, we focus on: salt mobility, multiple décollements and late basement control. Salt mobility concerns the ‘Hormuz’ basal detachment and the ‘Gachsaran’ upper detachment. For the latter, it is shown that mobility results not only from folding-related diapirism, but also from early gravity-driven migration from growing anticlines towards intervening synclines. Concentric folding between two detachment levels is directly observed in the Izeh zone (Central Zagros) where it is shown that the wave-length depends on the distance between the two active décollements and that the fold shape is a function of the level of erosion. Throughout the Zagros, detachment folds mainly developed during an initial thin-skinned phase of deformation, which was followed by the current thick-skinned stage. This succession is particularly well expressed in the Eastern Zagros where basement faults cut early detachment folds obliquely.