M Rostamiyan; M Khademi; S.S Eslami; H Shahbazi
Abstract
In the western part of Miami fault zone (MFZ) as a partial boundary of two main structural zones (Centeral Iran and Binaloud) in the Iranian plateau, since the fault is covered by alluviums or displaced rocks, poor and limited field data cannot solve the problems concerning deformation history and evolutionary ...
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In the western part of Miami fault zone (MFZ) as a partial boundary of two main structural zones (Centeral Iran and Binaloud) in the Iranian plateau, since the fault is covered by alluviums or displaced rocks, poor and limited field data cannot solve the problems concerning deformation history and evolutionary path of the MFZ. To facilitate unraveling the structural problem, we tried to conduct five experimental models using a combination of compressional, dextral and sinistral mechanisms with changes in the geometry of two main boundary faults. Based on the results, evidences from transpression with dominant dextral component are very similar to field observations along the western MFZ, including folds, Riedel shears, duplexes, fault geometry and bends. Based on the model, deformation in the western part of MFZ is accommodated by dextral non-coaxial shear with compressional component. The experimental model provided a proper insight about deformation history and style. It is proposed that the western part of the MFZ has been deformed by dextral non-coaxial shear with compressional component, and some resultant rotations have probably changed structural trends during time.
M Khademi; F Ghaemi; S.K Hosseini; F Ghaemi
Abstract
In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) ...
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In this paper, the feedback or interaction between tectonic and surface processes in the Binaloud Mountains and Neyshabour plain has been investigated. To achieve this, we have used topographic data, recorded earthquake data provided by the Geophysical Institute of Tehran University (Mashhad center) and field surveying results. Surface processes affect the propagation of tectonic thrust wedges in orogenic belts. In regions where tectonic processes have led to an increase in the surface slopes due to development of mountain highs, surface processes will justify the uplifted areas by smoothing the slopes, eventually shedding off a massive load of clastic sediments into the foreland basin. Because of their huge weight and volume, these sediments prevent the forward propagation of the wedge and therefore increase the accumulation rate of stress in the orogenic wedge. Also the increase of fault-plane dips in the orogenic wedge will make the slip along the fault planes hard or even impossible. Formation of out-of-sequence faults and back-rotation of preexisting thrust faults may be considered as results of these accumulated stresses. North Neyshaboor thrust fault is a later or secondary structure and can be considered as an out-of-sequence thrust because it cuts other thrust sheets and limbs of folds. Our research shows that the high volume of Paleogene/Neogen sediments in the Neyshabour foreland basin has prevented the forwards (southwestward) propagation of the Binaloud mountain range as the orogenic wedge. Releasing of the accumulated forces has therefore led to the development of the North Neyshaboor out-of-sequence fault and back-rotation of former thrust faults.
M Khademi; F Ghaemi; S.K Hosseini; F Ghaemi
Abstract
The fractures are one of the structures, which can be used as a tool to unravel the tectonic processes in a region. The measurements of the fractures were conducted in the footwall and hanging wall of the North Neyshabour Thrust, which is one of the active faults of the region. We separated the fractures ...
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The fractures are one of the structures, which can be used as a tool to unravel the tectonic processes in a region. The measurements of the fractures were conducted in the footwall and hanging wall of the North Neyshabour Thrust, which is one of the active faults of the region. We separated the fractures of the North Neyshabuor Thrust into tow sets of perpendicular and parallel to the fault, which suggests variations in tectonic condition. Clockwise rotation around vertical axis is the recent model, which is proposed for this region. Rotation model noted that the eastern part of NE Iran has been moving towards south and this magnitude increase towards the East. The southward movement of this region is in conflict with regional movement of the Iranian micro plate, which moves to the north. Increasing in elevation towards the east is caused by increasing in the shortening rate. Thus, a decrease in GPS vector towards the east suggests that the movement vector decreases towards the east. This does not indicate a decrease of shortening rate.
