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.
H Haji Hosseinlou; A Solgi; M Mohajjel; M Pourkermani
Abstract
The Khoy shear zone (KSZ) is exposed 130 Km north of Uremia and 650 km west of Tehran. Structural analysis in the Khoy Shear Zone (KSZ) indicated that they consist of NW-SE oriented various metamorphic rocks. They contain NW-SE trending moderate to steeply dipping mylonitic foliation to the NE. Stretching ...
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The Khoy shear zone (KSZ) is exposed 130 Km north of Uremia and 650 km west of Tehran. Structural analysis in the Khoy Shear Zone (KSZ) indicated that they consist of NW-SE oriented various metamorphic rocks. They contain NW-SE trending moderate to steeply dipping mylonitic foliation to the NE. Stretching lineation plunge shallowly to moderately towards NE. Thrust faults are oriented the same as mylonitic foliation. Ductile fabrics are superimposed by brittle structures. Orientation of the structures indicates that the main stress trend is NE-SW. Four deformation stages (D1-D4) identified in KSZ. The first two stages are ductile that superimposed by the two other ductile-brittle stages. Shear sense indicators such as S/C fabrics, shear bands, shear folds, book-shelf structures, fishes and mantled porphyroclasts indicate that the KSZ deformed via dextral transpression tectonic regime. The Khoy area contains both NW-SE striking dextral strike-slip and SW verging NE dipping ductile reverse shear fabrics. Ductile shear fabrics are overprinted by subsequent younger both thrust and strike-slip fault systems. Abundant syn-tectonic granitoids were intruded in the Khoy area during convergent. The shear deformation fabrics are well identified in both deformed intrusive and metamorphic-ophiolite complex. The geometry and kinematics of shear fabrics indicate a deformation partitioning in both ductile and brittle conditions during a progressive transpression tectonic regime. The KSZ deformed during an oblique convergence scenario between the Arabian and West Alborz- Azerbayjan blocks in NW Iran.
M Ramazani; M. R. Ghassemi; A Zanchi; M. R Sheikholeslami
Abstract
Theerosional window of Aghdarband , located in NE Iran to the SE of Mashhad is a unique place for study of the Eo-Cimmerian event. This event (Late Triassic-Middle Jurassic) resulted from clousureof thePaleothetys ocean and collision between the Iran and Turan plates. These two plates were separated ...
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Theerosional window of Aghdarband , located in NE Iran to the SE of Mashhad is a unique place for study of the Eo-Cimmerian event. This event (Late Triassic-Middle Jurassic) resulted from clousureof thePaleothetys ocean and collision between the Iran and Turan plates. These two plates were separated from each other before Late Triassic, and therefore they had different tectonic and sedimentary histories. At this time the Aghdarband area was located on active margin of Eurasia, and therefore the units that are exposed in the erosional wiondow of Aghdarband have basic differences with their counterparts in other places of Iran. During the Eo-Cimmerian event, the Aghdarband area was affected by a sinistraltranspression. Strain in this transpressional zone was intensively partitioned, and three major structural domains with different structural characteristics were formed in it. A sinistral strike-slip fault zone and an imbricate thrust fault zone were formed respectively in northern and southern part of the Aghdarband area. Development of this transpressional zone may be attributed to the oblique convergence between Iran and Turan plates during above mentioned time interval.
