JOURNAL OF GEOTECHNICAL GEOLOGY (APPLIED GEOLOGY)
Year:2011 | Volume:7 | Issue:3|Papers Count:10

The dissolution process kinetic of Gachsaran gypsites in the Chamshir dam reservoir is subjected to the study in the present paper. Kinetically evaluation of minerals (e.g. gypsum, anhydrite, limestone and …) are possible using experimental equations and dissolution test data. This evaluation determines the amounts of dissolution rate constant (K) and reaction order (n). Researchers have considered that the order of gypsum dissolution reaction during dissolution process is constant and is equal to 1. The present study demonstrated that Gachsaran gypsites during the solution reaction, regarding to its impurities, initially dissolve with high reaction order and afterward, their reaction order decreases after pass from the Cs (the concentration where the kinetics switches to another order), as the amount of reaction order changes from 0.1 to 1.8 during the dissolution process. The K amount also increases with increasing in n values. Regarding to the importance of n in generation rate of channels, in study of water seepage in location of dam reservoir this assumption that n is a constant value is wrong and exact determination of n needs to the study of gypsites dissolution process kinetic.

The Shahriyar (Ostuor) drainage basin, located in the Miyaneh area, consists of seven sub basins, namely, one of them is being the main basin (Ghazelouzan basin) and six subsidiary basins (inclusive rivers of Zanjanroud, Ajichay, Garmychay, Shaharchay, Gharangoo and Aydoghmosh). Structurally, this catchment area is part of the western Allborz-Azarbayjan and is composed of Paleozoic to Quaternary rocks. Climatologically, the Miyaneh area in accordance with Amber Grease Climography is semi-arid cold. In this survey 12 samples of water from river drainage basins for determination of various uses including drinking, industrial usage and agriculture have been analyzed. Due to the effect of geologic, climatologic and hydrologic conditions, the water is sodic and of high chlorinity, except samples of R1 and R5, which are only useable for drinking livestock, the rest of the samples are mostly used for drinking water and agricultural and industrial usage.

163 m of Dariyan Formation sediments have been studied through 89 thin sections. Also, index microfacies have been closely identified. Generally, index microfacies of the studied thin section are mudstone, wackestone, packstone and grainstone microfacies.In This study, contact border of Dariyan and Gadvan Formation was showed disconformity.According to percent of Allocame element, high percent of iron nodules and Gluconate and the situation of exiting from water, upper border of mentioned formation were showed contact disconformity. Due to sequence stratigraphy studies in section Zama's mountain section the lower and upper border in order Gadvan Formation and Kazhdomi Formation has erosional (Sequence boundary type one- SB1 (and included system tracts (Highestant System Tract-Transgresive System Tract- Lowestant System Tract). Overall in section of lap sequence grade 3 was seen. Age of Dariyan Formation continues from Aptian to Albian.

Mamzar stock, which is considered as a part of the Iranian Volcanic Zone, is located southwest of Sarcheshmeh and contains collection of granitoid, aplitic dikes and pegmatite. Its overall texture is granular and porphyroid. However some other textures may also be found such as pertitic-antipertitic, granophyric, micro-graphic and mirmekitic.According to field investigation, lithologic characteristics, behavior of rare and main elements' oxides, spider diagrams and geochemical specification, the intrusive rocks of the area belong to the calc-alkaline series and are from the subduction zone of the continental shelf. This magma may originate as the result of subduction of the Neo-Tethys oceanic crust and collision of the Arabian plate with the Iranian continental plate creating a volcanic arc. The collision of the Arabian continental plate with the Iranian one may have happened in the Upper Cretaceous and the mentioned granitoid formation probably coincides with the Pyrenean orogeny.

Controlling of any leakage in dams is a basic requirement for their safe design. For this purpose, doing of investigation on geological structures of the dam site is necessary for design of any impermeable systems. After the watering of the Zavin dam, in north east of Iran, leakage was observed from the left abutment when the water level was increased. An extensive study was performed to find out the reason of the leakage as well as proposing a mitigation measure. This study included an extensive field geological survey in dam site. Moreover based on the geological and the geotechnical information and a seepage analysis the design of the initial impermeable grout curtain was modified. A new method of grouting with balanced grouting pressure and water head was designed and utilized in improvement of the existing grout curtain while the water level in reservoir was considerably high. This execution method is called as "grouting with balanced pressure" here. The method was successfully used in the case of the Zavin dam. During the grouting operation, the grout suspension was regularly tested to avoid any segregation. This was important for satisfactory filling of the joints and discontinuities of the rock mass of the abutment. The operation resulted in complete control of the seepage in downstream side.

The Sarvak Formation is among Bangestan group reservoirs which is located in the Dezful embayment, southwest of Iran. This Formation has two distinct facies in the folded Zagros belt. This reservoir is mainly carbonate and situated between Kazhdomi and Surgah Formations. For electrical imaging of the well, special technologies can be applied. FMI is among such technologies. It has proved to be useful in evaluation of lithology and fracture characterization (whether large, small, open or closed fractures) in different minerals. This study focuses on the image logs in well #383 from Sarvak Formation, Ahvaz field. To perform electric logging in the wellbore, special tools such as Formation Micro Imager (FMI) are utilized. Resulted image logs are interpreted in an interval of 3417 to 4167 in Sarvak Formation. The results include determination of number and coordination of fractures, relative fracture frequencies in different zones, slope and strike of layers and stresses in wellbore based on core analysis and image log (FMI) interpretations in the above mentioned interval. The results are obtained on the basis of structural trends, bore-hole break out and also description of cores. In this well the largest fracture density was observed in zones D, E and F. The dip structure of Sarvak Formation is 7 degrees towards north and 30 degrees towards east. Three vuggy fractures, 15 probable open fractures with dip of 57 to 77 degrees and two strikes of West 25 East (S25W) -East 25 North (N25E) and East 75 North (N75E) -West 75 North (N75W) were detected. In addition 14 closed fractures with dip /slope of 52 to 80 degrees and three strikes of west 75 North (N75W) -East 75 South (S75E), East 25 South (S25E) -West 25 North (N25W) and West 60 South (S60W) -East 60 North (N60E) were identified in this Formation.

The volcanic rocks of Bayche-Bagh mine area in northern Takab are a part of volcanic activity continuing from Qorveh to Sahand. Volcanic rocks of the area could be divided into older group of acidic and younger group of intermediatebasic compositions. Acidic group are consisted of rhyolite, rhyodacite, latite and rarely andesite. The basic group comprised of trachyandesite, andesite and basalt. The magmatic positions of Bayche-Bagh volcanic rocks set in calkalkaline site, based on their chemical compositions. The tectonomagmatic diagrams used by rare-elements characterized the Bayche-Bagh volcanic rocks in a continental arc-setting.

The Khoshyeilagh Permo-Triassic bauxite horizon is a part of the Eastern-Alborz Zone which is located 50 km northeast of Azadshahr. This horizon with more than 3 km long and a thickness of about 30 m is located along the contact zone of Permian limestones and Triassic dolomitic limestones. The basal contact zone of the bauxite horizon is mainly undulatory, whereas the upper contact zone is concordant with the hanging-wall dolomitic limestones. Textural analysis indicates both allochthonous and autochtonous origins for the bauxite horizon. Based on mineralogical investigations, this horizon is composed of kaolinite, goethite, hematite, quartz and anatase as the main minerals and bohemite, diaspore, rutile, calcite, and svanbergite as the accessory minerals. Combination of geological, mineralogical and geochemical data indicate that the Khoshyeilagh bauxite horizon were developed from alteration and weathering of basaltic rocks. The high frequency of silicate minerals reveals immaturity and poor drainage of the deposit.