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Alireza Farrokhnia, Ali Sorbi,
Volume 9, Issue 2 (9-2015)

The studied region in this research (Alborz province) is structurally located in Alborz poly_orogenic system of northern Iran. The purpose of this research is combining the remote sensing and geology sciences to show fault lineaments by analyzing satellite data in a vast region and also comparison between lineaments layer and recognized faults in geology maps. Firstly, two scenes of Landsat ETM+ satellite images with 164-35 and 165-35 numbers were mosaicked and also according to coordinates of research area (46 30´ to 48 east longitude and 34 to 35 north latitude degree) have been crop. Then with remote sensing methods such as combination of bands, filtering, NDVI index to reconstruction the vegetation, principal components analysis (PCA) and band relativity in gray scale and color images  have been analyzed the satellite images. Finally, by using the above mentioned methods, the map of fault lineaments and map of lineaments density for Alborz province have been prepared and compared with recognized faults.
Siamak Baharvand, Salman Soori, Jafar Rahnamarad, Maseoud Joudaki,
Volume 12, Issue 2 (10-2018)

Earth is a dynamic system. Change is one of its features. At its surface, there is almost no region that over the past few thousand years has not affected its neotectonic activities. In fact, it can be said that active neotectonic is changing the surface of the earth. Among geological methods for analyzing active tectonic movements, deciphering the geomorphology and morphotectonic nature play a very important role, because many geomorphic complications are sensitive to active tectonic movements and the geometric analysis of these complications provides evidence of the type, rate, and configuration of active tectonic deformations. Moreover, these geomorphic indices at a regional scale provide basic reconnaissance tool to identify tectonically active regions, their susceptibility to tectonic deformation, and level of tectonic activity.
In the presented study, tectonic activities and geological structural features of the Vark basin in Lorestan province, such as the discontinuities that may be detected on satellite imagery as lineaments, and in many cases control landslide occurrences, have been analyzed using the GIS and remote sensing.
Material and methods
Neotectonic investigation in the area: in order to analyze and to evaluate the tectonic movements in the Vark basin, considering the validity of geomorphic indices, longitudinal gradient (SL), river meanders (S), basin hypsometric curves (HC) and asymmetry factor (AF) have been used.  After calculating the desired indices, the tectonic activity of the area has been evaluated using the index of active tectonic (IAT).
Vark basin lineaments map derived from satellite images with proper resolution: using remote sensing techniques and visual interpretation of the OLI Landsat 8 satellite imagery, all fractures and lineaments of the region were identified and then by preparing the rose diagram, the trend of the lineaments of the area analyzed.
Landslide hazard zonation in the Vark basin: In this study, in addition to plotting landslide occurrence Points, eight other factors were also investigated. In order to provide a map of the factors affecting slip, the digital elevation model (DEM) in ENVI 4.8 and ArcGIS soft wares were used and the maps of slope, slope aspects, altitude classes, area geology, land use, topography and precipitation were prepared. Then, in order to zoning the landslide hazard, fuzzy logic method has been used. Fuzzy logic is based on the fuzzy layers and the fuzzy inference process.
Results and discussion
Analyzing the Neotectonic of the Area: as stated above, the relative active-Neotectonic (IRAT) index is derived from the interpolation of the morphotectonic indexes. In this case, after reviewing the morphotectonic indices of the study area and determining the activity rate of each indicator, the classification or prioritization of these activities were done. The results obtained from calculating the active tectonic index indicate that the study area with IAT is equal to one, has an active neotectonic.
Preparing the Lineation Maps of the Area: in this research, the aim of the data processing including satellite imagery and digital elevation model is identification and extraction of fractures and faults in the Vark basin. To this end, we can use the integration of the information layers derived from the above processes. In this step, all layers of information are logged into the ArcGIS software so that their overlap can provide a map of fractures and faults. On each information layer processed there is a series of lineaments recognizable that can be visually distinguished. After extraction of lineaments by comparing them with bundle compounds and maps derived from digital elevation model and geological map of the region, the lineaments of fractures and faults were separated from other lineaments and their shape file map has been prepared. In order to plot the rose diagram of fractures and faults, the Polar Plots ArcGIS Extension was used. The results obtained from this rose diagram showed that the dominant trend is the northwest southeast followed the trend in the region.
Preparing a map of landslide hazards zoning in the region and investigating its relationship with the lineaments: In order to overlap layers affecting the area's landslide hazard, Gamma fuzzy operator (λ= 0.9) has been used and landslides hazard mapping prepared. Based on the results, 12.40, 8.25, 37, 32.61 and 9.73 percent of the area are located in the very low, moderate, high and very high-risk classes, respectively.
In order to investigate the relationship between the lineaments and the landslide hazard maps as parameters that are affected by the tectonic activities of the area, the lineaments map was integrated with the map of landslide hazard. The results show that the most of lineaments identified in the study area have a northwest-southeast trend that are similar to the main faults of the region and Zagros. It can therefore be said that the lineaments are influenced by the faults and folds mechanism of the region. According to the lineament density in areas in places that are exposed to landslides, one can understand the close relationship between the lineaments and the landslide.
Based on the results obtained from relative active tectonics index, the Vark basin has an active neotectonic, which leads to an uplift in parts of the basin, as well as tilting in the southern part of the area.
In this research, the tectonic of the area, and then the relationship between the lineaments and the map of the landslide risk, as two phenomena affected by active neotectonic were reviewed. Investigating the lineaments of the region shows that the dominant trend is fractures north-west-south-east and following the trend in the region. In addition, analyzing the relationship between the lineaments with the map of the landslide hazard of the area shows that there is a close relationship between the lineaments and the zones with high risk of slipping.
Hojjat Ollah Safari, Hamed Rezaei, Afsaneh Ghojoghi,
Volume 14, Issue 3 (11-2020)

The landslides, as a natural hazard, caused to numerous damages in residential area and financial loss. In many cases, we can forecast the occurrence probability of this natural phenomenon with using of detail geological and Geomorphological studies. This seems that one of the most effective parameters in landsliding phenomenon is structural parameters, especially faulting in rocky outcrops. For verifying this hypothesis, the Nargeschal area, as high potential of hazardous area, is selected as case study for investigation on influences of faulting on landslide occurrence probability. Many large composite landslides were happened in 2016 and hence, this area is enumerated an active zone of landsliding. This area with geographic attitude 55° 09' 06" to 55° 27' 21" Eastern Longitude and 36° 54' 23" to 37° 05' 15" Northern Latitude located in south of Azad shahr (in Golestan Provinces) placed in Northeastern of Iran.
Geological studies indicate that this area located in northern limb of Alborz fold belt (as a young fold-thrust belt with 900 km length) which formed in late Alpine orogenic events by convergence Afro-Arabian and Eurasian plates. In this zone, the structures have main NE-SW trends with main active faults such as Khazar and North Alborz faults, as reverse faults with north-ward movements. The remnant part of Paleotethyan rocks (which transported from collision zone toward southern part by low angle thrusts) located between these faults and formed the mountain-plain boundary hills.
Material and Methods
In this research, we investigated on effective parameters in landslide occurrence probability of Nargeschal area with using of remote sensing techniques, GIS environment abilities and complementary field investigations. Therefore, we have prepared the seven data layers of geological and morphological effective parameters which are affected on landslide probabilities. These data layers consist of: lithology of outcropped rocks, faulting condition, topographic slopes categorizes cultivation circumstances, seismicity condition, spring population (ground water condition) and surveyed occurred landslides. Then, the content of each data layer is weighted and classified into five classes in GIS environment. Finally, the content of each pixels in all of 7 layers are algebraically summed and recorded as an attributed table. Hence, the landslide hazard zonation map was prepared by drawing the isopotential surface map on the basis of quantities of attributed table by using of GIS functions in Arc view 3.2 software.
Results and Discussion
The results of this research illustrate that a high risk zone is located in central part of area as an oblique broad-stripe zone with NE-SW trend [6]. This zone is correlatable with high density of fractures zone and high population of springs and earthquake focus and also, taken place in Shemshak formation with shale, marl and siltstone rocky outcrops (upper Triassic- Jurassic in age). 
Also, the results of investigations on influences of structural parameters (especially faulting) in landslide hazard demonstrated that faults are indirectly impressed on this hazard probabilities via formed the high slope topography, poor strength faulted rocks, locating of spring presences and creation of seismicity, and hence, defined the spatial pattern of landslides.
Nargeschal area in Northern limb of Eastern Alborz is selected as case study for investigation on temporal relationship between Faulting and Landslides. The following conclusions were drawn from this research.
- It seems that the fault surface plays the role of rupture planes for landsliding.
- The structural factors also increased the ground slope and then, the close relationship is formed between landslides and faults.
- The results demonstrate the genetically relationships between landslides and faults in macroscopic scale in Nargeschal area.

Saeed Nazari, Alireza Arab Amiri, Abolghasem Kamkar Rouhani, Sadegh Karimpouli,
Volume 15, Issue 2 (9-2021)

Chahar-Gonbad region of Kerman province is geologically located in the southern part of central Iran zone, dominantly in Uromieh-Dokhtar volcanic belt. In this region, many high potential prospects, specially Cu-Au mineralization, have been detected during large scale exploration and reconnaissance phases. In this paper, remote sensing and field geophysics were used for alteration mapping on the surface and ore body delineation on the subsurface, respectively. To this end, we used an ASTER satellite image and different maps were generated by spectral technics such as false color composites and spectral ratios. Results showed argillic (and phillic) alteration in Bab-Zangoeie area is surrounded by propylitic alteration, which could be a promising evidence for Cu mineralization. Integrating these results with previous exploration studies led to selecting target area selection for ground study and field geophysics. We used both induced polarization (IP) and resistivity (RS) methods as two powerful geoelectrical methods by a pole-dipole array along four profiles. After preprocessing analysis, forward and inverse models were constructed in 2D section and 3D overlay model of joint IP/RS anomalies were constructed. Based on the obtained results, the deposit in depth where we proposed drilling targets. Further drilling operation have proved the mineralization in our proposed targets../files/site1/files/152/%D9%86%D8%B8%D8%B1%DB%8C.pdf

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