The Effect of Basal Cohesion Coefficient in Structural Style Mangharak Fault Zone with Use Analogue Modeling Method

The N-S strike-slip Mangharak fault zone is located in Zagros simply folded belt, and continuous from about Shiraz to south of Dehram for about 140 km. Various large salt plugs such as Jahani, Firuzabad, Gach in the middle part of Mangharak fault zone, and small salt plug in Kaylag thrust pierce the cover layers. Existence of salt plugs in this area indicates the presence of viscous basal decollement layers at depth, which may cause variation in structural style above and below the decollement. Spatial distribution of decollement layers are analyzed through experimental analogue modeling method. As a result when cohesion coefficient between basement rocks and sedimentary sequence is high, tapper angle of the thrust and fold belt is high and width of deformation is narrow. Existence of Hormoz salt Formation has decreased the cohesion coefficient between basement and cover sequence. Consequently, in the studied area the tapper angle of deformed belt is variable and closely related to the spatial distribution of the decollement layers. In the west of Mangharak fault zone, cohesion coefficient and tapper angle are high, width of deformed zone is low, however in the east of Mangharak fault zone, cohesion coefficient and tapper angle are low, and width of deformed zone is high.