Iranian Journal of Geology
Year:2016 | Volume:10 | Issue:37|Papers Count:7

Communication networks and roads are important part of the investments of each country. Beside of this, maintenance of these large communication networks and process of developing construction are among the causes of the degradation of natural resources. In this research, occurrence of landslides in Kiasar road, located in the south of Sari city, was evaluated by using basic physical model, SHALSTAB, and slope stability map of this area was determined by this model. First, the physical and mechanical properties of 15 soil sample near the main roadside were measured and compared with 115 cases of landslides around the road. Results of Square research, analysis of geological data, and laboratory tests showed that for all landslides occurrence, 43.49 percent of actual landslides have been located in unstable regions. Then, the roadsides have been distinguish from happened landslides, in natural conditions. Then a separated model has been run for each landslide. The results showed that whenever SHALSTAB model has been implemented by using roadside landslides, this model can simulated only 18.55% of slip points in unstable zones, and when SHALSTAB model implemented by using slips which occurred in natural conditions, by predicting 69.5 percent, is a successful usage.

The Panah-Kuh calcic and magnesian skarns are located about 50km northwest of Taft City in Yazd province. Intrusion of Panah-Kuh granodiorite stock with an Oligocene-Miocene age into limestone-dolomite rocks of the Jamal Formation led to the formation of calcic and magnesian skarn in the Panah-Kuh district. Values of d18O of the granitic rocks and d18O and d13C values of the calcite types were determined in this study. Based on these data, d18O and d13C values in the studied calcite types are lower than those of sedimentary calcites. These isotopic variations are mainly produced by infiltration of magmatic fluids into carbonate rocks in the Panah-Kuh deposit. Depletetion of the d18O and d13C value in the calcite types of Panah-Kuh skarn can be explained by magmatic fluids interaction (d18O =11.0‰) that interacted with unaltered limestone rocks at 350-450oC with X (CO2) = 0.05 and water/rock ratio of 25 to 50%.

Fault traces within the Qozlu fault tip zone, located at the southeast end of a segment of the North Tabriz fault, which reaches to the Bozqush deformation zone, represents the formation of a horsetail structure. There is, however, no information about the type of this structure or its deformation pattern. In this regard, study of topography (analysis of the relative elevation difference at two scales—within the overall deformation zone and in buffer zones along streams flowing within the zone), surface slope, asymmetry factor, and geological information indicate that: 1) the fault tip zone is a contractional horsetail splay; 2) a compressional tectonic regime is dominant within the fault tip zone and the trend of maximum compression is N20W-S20E; 3) two different fault zones with maximum and minimum tectonic activities are recognised along two streams within the fault tip zone ; 4) the overall dip-slip component within the stream-related fault zones is reverse or thrust. These results provide significant information about tectonics of the Qozlu fault tip zone and improve our knowledge of deformation within the North Tabriz fault zone. This study, also, demonstrates the importance of using stream longitudinal swath profiles to obtain tectonic information directly from topography.

The Yaralujeh vein index is located about 40 km NW of Ahar, East Azarbaijan. Based on geochemical studies, the original host rock is microdioritic in composition with calc- alkaline character, situated in an active continental margin volcanic arc. The mineralization is occurred as disseminated, stockwork and veins - veinlets containing quartz, carbonate and sulfide minerals in altered subvolcanic rocks (microdiorite). Pyrite, sphalerite, galena and chalcopyrite are the most important sulfide minerals in this area. The most important alerations in this area are sericitic and carbonatization, and the main alteration minerals are quartz, sericite, illite, albite, kaolinite, leucoxene, pyrite and late carbonates. Bivariate diagrams of Ba + Sr vs. Ce + Y + La and Zr vs. TiO2 and also values less than one for TiO2 indicate a hypogenic origin for altered fluids. The spider diagrams of REEs, normalized to both chondrite and average upper continental crust, show differentiation of LREE from HREE and depletion of LREE relative to average upper continental crust. Based on geochemical indicators such as Hf / Sm, Nb / La and Th / La and LREE enriched relative to the HREE, the most important ion complexes transition metal are Cl- complexes. Ce, Eu and Pr (Eu/Eu*, Ce/Ce*, Pr/Pr*) anomalies in ore-bearing vein and host rock indicates near-neutral pH in a redox environment for the alteration fluids in Yaralujeh Index.

The Asmari Formation in the southern flank of Mish anticline (in the north of Gachsaran) with a total thickness of 366 m is mainly composed of medium to thick limestone layers. Based on lithological studies, it is mainly composed of a periodic arrangement of marly limestone with very thick, thick and medium bedded limestone layers and in some parts it consists of dolomitic layers.The lower contact of the Asmari Formation with Pabdeh Formation is gradual and its upper contact with the Gachsaran Formation is conformable with some sharp lithological changes. Based on change in thickness of layers, color and lithology, this carbonate sequence is subdivided into three lithological units.In Biostratigraphic studies, 28 species belonging to 41 genera of foraminifera were recognized. According to recognized biozone and foraminifera assemblages, 4 biozones and one undetermined zone were classified according to Laursen et al., 2009. The age of the Asmari Formation in this section is Oligocene (Rupelian-Chatian) to Early Miocene (Aquitanian-Bourdigalian).

Hydro-geoelectric properties of the Asmari and Ilam-Sarvak formations in Susan Syncline (located in Middle Karoon Basin), North of Izeh, were investigated to recognize electrical resistivity ranges of dry and wet limestone, karstification, and fractures and determine the areas with high potential for groundwater exploitation. For this purpose, the resistivity data were collected in 245 vertical geoelectric sounding (VES) using Schlumberger array in the contact of limestone and adjacent alluvium. The resistivity data were interpreted as one-dimensional and two-dimensional tomography (using RES2DINV software). The resistivity curves of VES in the Asmari Formation have lower value and ranges of resistivity than the Ilam-Sarvak Formation which can be understood by high yield of the aquifers from the smooth descending VES curves. Interpretation of two-dimensional geoelectrical tomography revealed that the Ilam - Sarvak Formations have considerable potential groundwater in crushed zones but the karst development and cavities in them are less than the Asmari limestone. The spring discharges from the Ilam-Sravak Formations in Susan area is in relation with the contact of compact limestone and water bearing fractured zones. Despite the lack of major springs in the Susan Syncline,the results of the hydro-geoelectrical investigation showed the Asmari limestone aquifer, has a high groundwater potential. The electrical resistivity of the Asmari Formation is lower than the Ilam-Sravak ones because of the higher porosity of limestone matrix in the former.

The presence of hot springs, travertine outcrops, hydrothermal altered area and active tectonic in the north-east of Takab city in the West Azarbayjan province indicate that there is a geothermal system in the area. In order to characterize the geological structures associated to the geothermal system in the region, a gravity survey was carried out in 140 stations which covered an area about 600 km2. Necessary modifications such as Bouguer, topography and free air were applied over data to obtain complete Bouguer anomaly field. Then, residual gravity anomaly field was calculated by subtracting the regional gravity field from complete Bouguer field. The regional gravity field was calculated by fitting a three-order polynomials surface over the complete Bouguer field. The calculated residual gravity map shows two negative anomaly zones (A1 and A2) in the study area. In geothermal exploration, negative gravity anomalies are considered as probable reservoir of geothermal systems. The horizontal and vertical derivative maps show complicated fracture zones in the study area. To obtain more information, the depth estimation carried out using Euler method. Estimated depth for the top of negative anomaly source in zone 1 is between 1000 and 2000 m. Finally, 3D inversion of the data was performed using Li and Oldenburg algorithm to show an image of the reservoir in the depth. The results of 3D inversion show a significant negative density contrast that occurred only in zone 1. Therefore, the reservoir of the Takab geothermal system is located in the depths between 3000 and 5000 m in A1 anomaly zone.