Recent Crustal Deformation in SW-Zagros, Iran, Controlled by Syncline Core Extrusion

In thin-skinned fold-thrust belts, the style of deformation is critically depends not only on the resistance to sliding along basal detachment, but also on the presence of intermediate decollement levels or/and ductile units within the wedge. In ZFTB the incompetent units known as detachment levels like the Gachsaran formation (Shallow level) and the Hormuz saltseries (deep) affect strongly the deformation style. However, in many cases shallow level detachment of the Gachsaran unit controls this shallow deformations, but owing to the different facies of this unit in the studied area it is reasonable to other incompetent shallow units (e.g. the middle Miocene Mishan Fm. and the Upper part of Aghajari Fm.) to partially decoupling deformation form the underlying sedimentary units, and have permitted the re-activation of pre-existing syncline structures, through upward extrusion of the syncline core. Owing to the concentration of significant amounts of young deformation across the structure (specially northern hinge) in the style of erosional surfaces, the East West trending Anve syncline in north of the Bastak town, considered to be one of the most active structures in the region. In this study, we try to define the vertical deformation of a geomorphic marker as well as using tectonic morphology techniques to shed light on the deformation extend and pattern in the eastern and western parts of the structure. However, the microseismic data do not suggest any significant event related to this kind of deformation, but studying deformation style and relative uplift rate estimation could be beneficial dealing with earthquake hazards in the region.