Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

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

Document Type : Original Research Paper

Authors
Morteza Pirouz 1
Mohammadreza Ghassemi 2
Abbas Bahroudi 3
Abdollah Saeidi 4
1 School of Geology, University College of Sciences, Tehran University, Tehran, Iran
2 Geological Survey of Iran, Tehran, Iran
3 School of Technical Sciences, University College of Technical Sciences, Tehran University, Tehran, Iran
4 Research Institute of Earth Sciences (GSI), Tehran, Iran
Abstract
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 is 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.
Keywords
Zagros
Mangharak Strake-slip fault zone
Basal decollement
Analogue modeling
Hormoz salt Formation
Tapper angle

Subjects

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Scientific Quarterly Journal of Geosciences
Volume 16, Issue 61
Autumn 2006, Vol. 16, No.61
Autumn 2006
Pages 178-187