مجله زمین ساخت
پیاپی 9 (بهار 1398)

The study of the fracture systems and their spatial extensions can help in developing oilfields, reducting the costs of exploration and improving overall understanding of the hydrocarbon reservoir systems. In this study, using different tools such as Landsat OLI-8 satellite imagery, remote sensing techniques, by Geomatica and Rockwork softwares, the structural lineaments map of the Bibi Hakimeh oil field (Surface fractures of the field in Aghajari Formation), is prepare and compared by the data obtained from FMI logs (In Asmari Formation). According to the circular diagram, in Bibi Hakimeh oil field the shear fractures (SO1) and surface axial parallel fractures (SX) have the highest percentages. According to the density map, the highest lineation densities have been seen in the middle belt of the fold from the east to the west, adjacent to the axis of the fold, that are related to the tensile joints in the axis. According to studies on the density map, extraction oil wells in the Bibi Hakimeh oilfield, mainly found in the areas with the highest fracture density. Comparison between the results of the fracture process of FMI 4 logs related to Bibi Hakimeh oilfield with the results of structural studies in this study shows that the trend of fractures in FMI data in the East part are completely compatible with the results of remote sensing studies,Therefore, studies are proposed to develop extraction wells and location for the exploration of new exploratory wells in the east and in sections with high fracture density obtained in this study.

The Bakharden-Quchan Faulted Zone is located in central Part of thrusted -folding belt of kopeh Dagh in NE border of Iran-Turkmenistan with array of active right lateral  strike-slip faults by trending NW-SE that their ends have bent to joint blind faults in thrusts. Mechanism changing faults to reverse have caused to increase stress, shortening by thrusting in their ends bending. Most of the historical and instrumental earthquakes have distributed around faulted system of Bakharden-Quvhan Zone. Seismicity results of this zone with micro-seismics and computing parameters of b-value, fractal dimension (D) and mapping of local stresses distribution could have achieved us precious data on crust tension distribution, mechanism faults and system fault changes during time and place of probable occurrence future earthquakes. In neo-tectonic active zone b < 0/6 to 1/1 and D changes between zero to 2. If b< 0/6 and D closes to zero, faults and earthquakes will concentrate in asperities with high rate of stress but if b> 0/6 and D closes to 2 faults and earthquakes will scatter in whole of zone with low rate of stress. Occurrence of major earthquakes are not far away expectation in edge of asperities although there is a possibility that they gradually loss energy to get inactive because the seismology way of releasing energy in these faults is, when group of faults approach to motion threshold are increased b-values and other group of faults are accumulating energy, so their b-values are decreased

The Birjand anticline is a type of the fault propagation fold that is formed above a blind thrust fault and is divided into 11 segments by 12 tear faults. In this research, the Late Cenozoic deformation associated with the Birjand blind thrust has been evaluated. To this end, the fractal dimension of drainage patterns and its statistical properties is calculated on the Birjand anticline. Accordingly, the spatial distribution of windows with the fractal dimensions close to 2 are within the regions that are low slope, low height and marl-tuff units. These windows are more relative frequency in the northern limb of the fold, also to the northwest end segments (10 and 11). This issue is related to a gentle back-limb of the fold and flat crest of the end segment 11. For Birjand anticline toward northwest, lateral growth of the fold is clearly at the Dasht-e Birjand and close to the Shekarab kuh to form as gently-dipping alluvial fans deposited. In the progressive stages of the Birjand anticline growth, segments from northwest to the southeast have grown more structurally mature and the values of the fractal dimension are lower. In the back-limb and flat crest of the fold, the drainage patterns are closer to trellis and dendritic and the fractal dimension approaches to 2 and in the fore limb are intermediate and steep slope, the drainage patterns are varies to parallel and the fractal dimension is decreasing. The surface deformation due to the Birjand blind thrust geometry controls the pattern and density of the drainage network by effects of topography and lithology and the result is a high the fractal dimension in the region with more active tectonic.

The occurrence of hydraulic failure is one of the most important geotechnical problems in the core of dams. Excessive water pressure increase during the first impounding period results in a significant reduction in the effective stress and consequently reducing the shear strength of the core materials of the earth's dams, which can overcome the water pressure on the effective stress and the underlying hydraulic cracking. In this research, the hydraulic failure of Taj-Amir earth dam with static loading conditions was completed at the end of construction and the steady state period was studied by Plaxis software with Mohr-Coulomb behavioral model. The analyses show that water pressure ratio (Ru) and stress-strain values are acceptable and there is no problem in terms of failure of dam. Also, the critical ratio of arching is 0.53(47%), which is about one-third the height of the core from the foundation, it is conventional, and the hydraulic failure does not occur even with the occurrence of an arching phenomenon at the core of the dam.

Morphotectonics expresses the relationship between geomorphology and tectonics. The plain of Birjand is located in eastern Iran. The purpose of this study was to identify the physical parameters of the study area also, the performance of these parameters is based on changes occurring on the surface of the earth, this purpose, field data and topographic maps have been used and the following results are achieved. The AF range varies from 28.11 (southwest) to 0.61 (southwest). The range of changes in T is from 0.72 (southwest) and 0.23 (southwest). The highest Smf is 1.91 (southeast), the lowest is 1.02 (southwest) of the basin. The calculation of the VF index showed a slight neo-tectonic upsurge. The lowest value is S 1.05 (west) and the largest is 1.16 (west) of the region. The lowest value of the index is Re 0.19 (southern part) and the highest value is 0.72 (south). Hypsometric integral is calculated; the highest value is 0,505 (Southeast) and the lowest value is 0,166 (Southwest). The Dd index is (South East) with the lowest 1.59 and the Southwest 2.25. The highest Te (southeast) is 2.55 and the lowest (southwest) is 0.47. The highest value of the index C (southwest) is 0.62 and the lowest (southwest) is 0.44. The parameter Iat shows; the plain of Birjand is located in the active degree of morphometric changes, and these active areas are more in the southern range (Bagheran mountain).

Yazd block in Central Iran is a district of active deformation within Arabia-Eurasia collision zone. The study area is situated in southwest Yazd and it is surrounded by Dehshir fault in east and Mehriz fault in west. This NW trending fault system comprises numerous evidence for active faulting. Major and minor fault segments were mapped in satellite images in order to recognize fault zones structural and geomorphic characteristics. Epicenter location for five instrumental earthquakes with magnitudes ranging from 4 to 5 are defined in Tang-E-Chenar fault zone and probable causative faults are distinguished. Active NW trending Tezenj fault is introduced in this paper for the first time. Dominant fault mechanism involves right-lateral strike-slip and reverse movements observed all over the region representing recent fault activities. There are several geomorphic data demonstrating dextral strike-slip offsets in rock units, Quaternary alluvial fans and qanats along the faults. There is evidence for right-lateral offset in Triass units for ~840m along Taft fault and for ~2250m in Lower Cretaceous rocks along Mehriz fault. Right-lateral offset of alluvial fans ranges from ~140m to ~500m along Turanposht fault. Geomorphic analyses are together with field geologic observations and fault geometric and kinematic measurements.