Tectonics
Masoud Biralvand; Mohammad Mohajjel; Mohammad Reza Ghassemi
Abstract
In Takht-e-Suleiman region, travertine deposits are widespread in the footwall of the Chahartagh fault. Three factors played roles in forming travertine in this area: magmatism and high geothermal gradient, existence of carbonates between thermal source at depth and travertine springs on the ground, ...
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In Takht-e-Suleiman region, travertine deposits are widespread in the footwall of the Chahartagh fault. Three factors played roles in forming travertine in this area: magmatism and high geothermal gradient, existence of carbonates between thermal source at depth and travertine springs on the ground, so that the hydrothermal solution can provide the necessary ingredients for the formation of travertine. The third factor is extensional faults and fractures to conduct water containing dissolved calcium carbonate up to the surface. Absence of travertine on the top of the metamorphic basement, even in the footwall of the Chahartagh fault, highlights the essential role of second factor in formation of the travertine. Sources of travertines in this area are carbonates from the Jangoutaran and Qom formations, with the more emphasis on the latter based on our data. Right-lateral kinematics on the Chahartagh fault led to an NNW extension in the southeastern termination of the fault, paving the way for emergence of the travertine. However, there is evidence for a regional NE extension responsible for NW-SE normal faults in the area. Such an extension may be associated with slab rollback and slab breakoff of the Neotethian oceanic lithosphere, lithosphere delamination deformation or basement-involved thick-skinned deformation in this area.
M Biralvand; M Mohajjel; M.R Ghassemi
Abstract
In this study, brittle deformation in Takab complex is discussed. Deformation in the Takab area has been controlled by two sets of major faults. The first set is characterized by NNW-SSE trending steeply-dipping dextral strike-slip faults with reverse component. The second set includes WNW-ESE trending ...
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In this study, brittle deformation in Takab complex is discussed. Deformation in the Takab area has been controlled by two sets of major faults. The first set is characterized by NNW-SSE trending steeply-dipping dextral strike-slip faults with reverse component. The second set includes WNW-ESE trending moderately-dipping reverse faults which have been obviously displaced by the first set. The basement metamorphic rocks are exposed in the hangingwall of the faults indicating thick-skinned type of deformation and exhumation in the area. The major strike-slip reverse faults have resulted in dextral inclined transpression in the Takab complex area. Fault-related folds in hangingwall and footwall of the faults especially in the Cenozoic sediments indicate young activity and uplift in the area. Development of normal faults and local folds, as well asthe occurrence of earthquakes in the area imply that it is tectonically active. Structural analysis in this area reveal that the major steeply-dipping strike-slip reverse faults have controlled deformation and changedthe homogeneous strain to partitioned strain.Deformation of Cenozoic rocks overlying the basement metamorphic rocks indicate a dextral inclined transpression. Deformation in the younger sedimentary cover (Cenozoic sediments) is related to thick-skinned deformation in the basement metamorphic rocks.
M. Mohajjel; M. Biralvand
Abstract
Abundant chevron folds were produced in well-bedded red thin layers radiolarites in Kermanshah area. Various fold hinge area structures were produced due to competency contrast and change of thickness in radiolarian shale and thick-bedded limestone intercalation in radiolarite sequence. Different styles ...
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Abundant chevron folds were produced in well-bedded red thin layers radiolarites in Kermanshah area. Various fold hinge area structures were produced due to competency contrast and change of thickness in radiolarian shale and thick-bedded limestone intercalation in radiolarite sequence. Different styles of folding exist in massive to thick-bedded limestone and shale where they are inter-bedded with radilarites. Unique thin layers of the radolarite layers were folded in parallel shape but change of folds shape and mechanism were produced where thick bedded limestone or thin layers of radiolarian shale intercalations exist. Fold accommodation faults were generated in cases during folding. Geometry and style of folding indicate that deformation in radiolarites was produced by parallel folding due to buckling mechanism with southwest vergence. Thrust faults were generated during later stages, displacing some parts of the folded radiolarites.
