A. S Khalifeh Soltani; S. A Alavi; M. R Ghassemi
Abstract
Fractal analysis of drainages and fractures is a useful tool to determine the maturity structure of a region. With the help of fractal geometry, this study investigates the fractal dimension of drainages and fractures in the southwestern part of Lenjan, and examines the role of geological structures ...
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Fractal analysis of drainages and fractures is a useful tool to determine the maturity structure of a region. With the help of fractal geometry, this study investigates the fractal dimension of drainages and fractures in the southwestern part of Lenjan, and examines the role of geological structures after determining the most active part of region. In order for fractal analysis of fractures and drainages, box-counting method has been used. To achieve this, four parts A, B, C and D of high structural density were first detected in the region, and the fractal dimensions of drainages and fractures were then calculated and compared. Results of fractal analysis of fractures suggest that sector B is the most active part of the region, while fractal analysis of drainages indicates greater tectonic activity in sector A. The larger number of earthquakes and higher density of fractures in sector B, however, could indicate it as the most active part of the study area. Therefore, contradicts in different results obtained from the fractal dimension analysis of fractures and drainages can be explained by the varieties in lithology. The structural studies indicate the existence of a dextral transpression zone in the study area. The dextral transpression zone resulted in uplift of sector B by development of positive flower structures in this part of the region. Therefore, increased tectonic activity in part B is due to formation of positive flower structures and consequent tectonic uplift.
A Malaekeh; M.R Ghasemi; S Hakimi; A Bahroudi
Abstract
The Vijehnan anticline is located to the south of the Gilan-e-Gharb, in the simply folded belt of the Zagros. For analyzing the geometry and kinematics of the anticline, we first produced a geological map using a variety of satellite imagery, published geological maps and field studies. Four structural ...
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The Vijehnan anticline is located to the south of the Gilan-e-Gharb, in the simply folded belt of the Zagros. For analyzing the geometry and kinematics of the anticline, we first produced a geological map using a variety of satellite imagery, published geological maps and field studies. Four structural cross sections (A1-A2, B1-B2, C1-C2, D1-D2) perpendicular to the fold axes are produced in AutoCAD software. To analyze the geometry and kinematics of this fold, the horizontal shortening has been calculated for two cross sections. The average shortening of these cross sections is 11 percent. Kinematics analysis of the Vijehnan anticline based on the Publet & McClay model (1996) indicated that the geometry of the anticline is of detachment fold type. This result is also confirmed by the scheme which was introduced by Jameson (1987). To ensure the accuracy of the results, aspect ratio of the fold have been used which is presented by Sattarzadeh et al. (2000). The calculation of this factor indicates that the Vijenan anticline classified as detachment fold.
T Naderi; A ShafieiBafti; M Shahpasand-zadeh
Abstract
Structural data from the Kuh-Banan oblique-slip fault system show that this active fault controls the structural architecture of the Tikdar-Goorchoieh area, north of Kerman. The Kuh Banan fault system is consisted ...
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Structural data from the Kuh-Banan oblique-slip fault system show that this active fault controls the structural architecture of the Tikdar-Goorchoieh area, north of Kerman. The Kuh Banan fault system is consisted of three fault branches with mean trend of N70E in the north of the Tikdar - Goorchoieh village. These fault branches with a dip of 50-70 toward the northwest and slip rake of 50-80 N indicate the prevalent reverse with right-lateral strike-slip motion of the fault. The main strand of Kuh-Banan fault system with a northwest-southeast strike is reported between the Dehsu rock series and Shemshak Formation whereas the fault branches with a northeast-southwest trend are situated between the Hojedk Formation and Neogene alluviual deposits and Quatrnery sediments. In this area, the Dehsu rock series (Late Neo-Proterozoic-Lower Cambrian) is composed of dolostone and evaporitic rocks which thrusted over the sandstones, shales and limestones of the Hojdak Formation (Jurassic). According to the structural evolution of the Kuh-Banan fault system in the study area, the first fault branch (F3) with three fault slip motion in the northeast-southwest direction has developed between the Shemshak Formation and Dehsu rock series in north of Tikdar. The later fault branches of F1, F2, and F4 with the same trend have propagated from the main fault and developed between the Dehsu rock series with the Hodjek, Shemshak and Dahu (equivalent of Lalun) Formations.
N Sahabi-Fard; A Yassaghi; M.G Hassan-Goodarzi
Abstract
Zagros fold-thrust belt has been crossed by different transverse faults with NNW-SSE trend and dextral mechanism. These faults often show en-echelon geometries on the surface because of presence of detachment layers at base and within the cover sequence. The Karehbas fault is one these faults located ...
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Zagros fold-thrust belt has been crossed by different transverse faults with NNW-SSE trend and dextral mechanism. These faults often show en-echelon geometries on the surface because of presence of detachment layers at base and within the cover sequence. The Karehbas fault is one these faults located in Fars province about 65 km to the east of the Kazerun Fault zone. Presence of the Hormoz salt as a basal detachment and ductile horizons within the sedimentary cover have caused the fault to appear on the surface as several north-northwest-trending en echelon segments. At least six segemnts have been recognized in northern and southern parts of the Karehbas fault. In this study two southern segments, the Mengharak and Kalagh segments of the Karehbas fault zone to the south of Firuzabad are introduced and their mechanism are analyzed. Riddle and anti-riddle faults and drag folds and terminations are used to analyze the dextral kinematic for both segments. These strike-slip fault segments terminate in thrusts that are sub-parallel to the regional the Surmeh and Kalagh thrusts in the south. These fault terminations are in the hanging-wall of the Surmeh and Kalagh thrusts, and expose formations that are older than those in the hanging-wall of the latter thrusts. Therefore, the Mengharak and Kalagh segments introduced in this study have strike-slip mechanism, and according to this mechanism, their geometry and their structural position in continuation of the northern and central segments of the Karehbas fault, they are introduced as the southern segments of the Karehbas fault . Based on the thrusting of the Asmari Formation over the Bakhtiari Formation in the positive flower structure along the Mengharak segment, the minimum amount of displacement on these fault segments are evaluated equal to the thickness of the Mishan Formation.
B Zamani; M Jalilpour; M Moayyed; M Faridi
Abstract
The Study area is located in 15km Northeast of Tabriz in East-Azarbaidjan province. The rock units in the study area are limited and consist of different members of the Upper red formation (Miocene). Salt bed (Miocene) that diapired is related to the base of the mentioned formation. Due to the rising ...
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The Study area is located in 15km Northeast of Tabriz in East-Azarbaidjan province. The rock units in the study area are limited and consist of different members of the Upper red formation (Miocene). Salt bed (Miocene) that diapired is related to the base of the mentioned formation. Due to the rising of this salt diapir, various structures such as marginal reverse faults, radial normal faults, folds and karsts are developed. In the Northern part of the Tabriz fault, there are a set of basin structures and diapirs, which all have a NW-SE extension axis. The Khaje salt diapir is formed in the southern margin of one of these basins. The different parameters affecting the rising of this salt diapir from which the most important one is the tectonic regime of the study area. The compressional stress causes the formation of these basins. Furthermore, the contact between the Tabriz fault and Nahand (NW-SE) minor fault prepared a weak zone to rise the Khaje salt diapir. After the beginning of rising, other parameters such as buoyancy force, stability of compressional stresses and differential loading have caused the continuing and rising of the Khaje salt diapir. The Khaje salt diapir is young and still rising. In addition, analytical model analysis is evaluated diapirism initiation time about 31000 years. In terms of purity amount, NaCl percentage is very high; where there are no KCl and MgCl2 impurities; therefore, it is suitable for dissolution process. The marly interbeds of salt would make some difficulties in dissolution process. From the gas storage point of view, the depth of salt diapir and the evaluation of the reservoir volume are essential for underground researches and in order to get the accurate results 2D and 3D seismic studies are needed.
R. Nadri; M. mohajjel; A. Bahroudi
Abstract
The NNW-SSE striking Bidhand strike-slip fault system cut and displaced the Cenozoic volcanic and sedimentary rocks of the Urumieh-Dokhtar magmatic arc in south Qom. Structural evidences show that at least 16 km horizontal displacement in the Eocene volcanics has been caused due to dextral strike-slip ...
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The NNW-SSE striking Bidhand strike-slip fault system cut and displaced the Cenozoic volcanic and sedimentary rocks of the Urumieh-Dokhtar magmatic arc in south Qom. Structural evidences show that at least 16 km horizontal displacement in the Eocene volcanics has been caused due to dextral strike-slip movement along this fault. The compressional and extensional terminations were developed at the western block and not observed at the eastern one. The reverse and thrust faults associated with the drag folds were generated in the northwestern compressional termination and gabbroic sills were intruded in the southwestern extensional termination. Younger syenitic and granitic intrusive (Miocene) were intruded in the vacant space of the northern compressional termination and releasing zones along the central straight segments of the Bidhand fault. Gabbroic sills in the extensional termination at the south-western area of the Bidhand fault were folded and thrusted towards northeast due to the later deformational events.
M. A. Ganjavian; S. Shahriari; A. Yassaqi
Abstract
Fars region in southwest Iran lies at the Zagros foreland and is bounded to the north and east by the Zagros thrust, to the west by the Kazerun fault, and to the south by the HormozStrait and the Persian Gulf. Thrust faults and associated folds are the main structures in the Fars region. The structures ...
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Fars region in southwest Iran lies at the Zagros foreland and is bounded to the north and east by the Zagros thrust, to the west by the Kazerun fault, and to the south by the HormozStrait and the Persian Gulf. Thrust faults and associated folds are the main structures in the Fars region. The structures are trending NW to SE, the same trends as in the Zagros fold- thrust belt. The structural analysis of four anticlines in the interior Fars region based on the interpretation of seismic reflection lines and construction of structural sections on the basis of well data and field measurements indicates that fault propagation folds and fault detachment folds can be distinguished taking into consideration the geometry of the folds and the fault-fold relations. Based on measured parameters, the Ghareh Bulagh anticline is consistent with a fault propagation structure, while the Derz and Shirkhan anticlines with fault detachment structures. According to seismic reflection profiles and structural cross sections, the Chahkileh antiform is converted to a syncline at depth. The extent of shortening, based on the balanced structural cross sections, has been calculated to be around 14 percent.
