جستجوی مقالات مرتبط با کلیدواژه « میانه » در نشریات گروه « زمین شناسی »

Hesar gold mining area is located in Iran Alborz-Azerbaijan zone. The predominant lithology in the mineral range is volcanic, subvolcanic, and sedimentary rocks of the Cenozoic period, which include volcanic and pyroclastic rocks, andesite-trachyandesite, basalt, eicombrite, and tuffs of the Eocene age and related to the Laramid orogenic phase under the influence of Laramide. Expansion phase of volcanic lava that erupts from several fissures and emerges in the form of delirious dykes and floods and stocks, mainly dacite, rhyodacity with Oligocene age, and alterations related to these masses such as silicification, pyritization and caudal formation Major mineralization in the study area includes pyrite, goethite, magnetite and gold, which is mineralized in two phases and is mainly selective and dispersed. Gold mineralization is the result of the decomposition of pyrite and arsenic pyrite, which is free in the field. The rock has been found to be related to the second phase of volcanic and semi-volcanic outcrops of the Oligomocene age. The results obtained from microscopy studies of fluid shortcuts in quartz mineral indicate that the homogenization temperature varies in the range of 140 to 260 ° C and also the melting temperature of the last ice crystal changes from -0.1 to -9. ° C and salinity is between 0.18 to 14% by weight equivalent of NaCl with a frequency range of 2 to 6% by weight equivalent of NaCl.

Intrusive masses are exposed in the Bostanabad-Mianeh axis with the northwest-southeast trend. The rocks are known as granite in general geological maps. Detailed studies in this study have also shown the presence of syenites which their petrology was considered in order to investigate the Zagros orogeny development in northwestern of Iran. The magmatic rocks of the region are the result of magmatism of the Uromieh-Dokhtar magmatic belt and include intrusive, volcanic and pyroclastic rocks with sedimentary units. Syenites of the Bostanabad-Mianeh axis are along with large volume of granites. Syenites provides important information about the interaction of the crust-lithosphere mantle, magma evolution processes, tectonics and crustal growth. In this study, syenites are divided from granitic rocks and their geochemical properties have been investigated to determine their tectono-magmatic and Petro-genetic conditions.

During field study, samples from the syenite and granite outcrops were collected for petrography, geochemistry and determining magmatic series and the magma origin. For geochemical studies, 13 samples of intrusive rocks with the lowest degree of alteration were chemically analyzed by ICP-MS and ICP-OES methods in the Act Lab Ontario Canada.

The Bostanabad-Mianeh axis in northwestern of Iran and in the East Azerbaijan province is part of the Cenozoic magmatism of the Lesser Caucasus towards southeastern Iran. Magmatism is related to the subduction of the northern ocean of Neotethys during the collision of the Arabian Plateau with Eurasia and its subsequent events. The presence of arc-type magmatism in the regions of Azerbaijan, the Alborz Mountains, Talesh and the Lesser Caucasus all indicate the subduction of the Neotethys branch with the Eurasian plate. Due to the LILE and LREE enrichment and the HREE depletion, the source of the magmas for the studied syenites are originated from an enriched mantle source in the continental lithosphere in the subduction zone belonging to post orogenic extension events. Consequently, the formation of the intrusions is related to mantle melting which is enriched and fed by fluids and melts and finally contaminated with crustal material during the ascent.

The Avin kaolin deposit is located about 35km of northeast of the Mianeh town, East-Azarbaidjan Province, NW Iran. Field evidence and petrographic studies indicate that development and formation of this deposit is genetically related to alteration of dacite rocks of Eocene- Oligocene age. In attention to mineralogical data, this deposit consists of minerals such as kaolinite, quartz, muscovite-illite, cristobalite, rutile, orthoclase, and goethite. Investigation of some geochemical parameters such as values of TiO2, Ba+Sr, and Ce+Y+La show that development of this deposit is related to function of two processes of  hypogene and supergene. Incorporation of the obtained results from mineralogical studies, mass changes geochemistry, and variations trend of elemental ratios indicate that chemistry of altering fluids (pH and Eh), surface adsorption, scavenging by metallic oxides, fixation in neomorphic mineralogical phases, ratio of fluid to rock, and amount of availibility to complexing ions are six effetive parameters in mobilization, distribution, and enrichment of trace and rare earth elements in this deposit. Geochemical analysis indicates that decrease of  Eu anomalies in kaolinized samples was related to destruction of plagioclase minerals of the dacitic rocks by high temperature hydrothermal fluids and decrease of negative Ce anomalies is due to development of kaolinization process by fluids with acidic-oxidizing nature.

A metamorphic rock complex consists of slate, phyllite, micaschist and marble with NE – SW shistosity has cropped out in Neybaghi area in the NE of Myaneh.  Impure marbles occur as thick and thin layers or massive bodies within the centeral area of this complex. Textural and mineralogical evidences, revealed two metamorphic stages.  The early stage is testified by the minerals such as pyroxene (diopside), epidote (clinozoisite), amphibole 1 (edenite-pargasite) and plagioclase 1.  The main stage have chlorite (clinochlore), phlogopite, amphibole 2 (tremolite) and plagioclase 2.  P-T-XCO2 have been estimated for the early and main stage of metamorphism by computing nonideal and asymmetrical fugacity and activity and programing in THERMOCALC software for fluid and solid phases.  The estimations give pressure, temperature and XCO2 of 9.5Kbar, 660°C and 0.35, whereas the main stage has been constrained at P=4.2Kbar, T=510°C, XCO2=0.4. The obtained P-T path shows that the Neybaghi marbles were formed under medium pressure condition and overprinted by a low pressure metamorphism.  This type of P-T trend can be formed in collisional tectonic regime.

The Garmichay area in the north of Mianeh, NW Iran, features schists, amphibolites, calc-silicates, marbles and granitoids. Granitoids are of S- and A-type nature. Partial melting is the main generation mechanism, the progenitor is a pelite enriched in muscovite and the major melting reaction is muscovite dehydration. The ASI for the S-type granite varies between 1.12-1.5 indicating peraluminous character and crustal origin. Both granitic types are enriched in LREE in relation to HREE with negative Eu anomalies. Lan/Ybn ranges are 1.49-3.09 and 1.34-1.99 for the S-type and the A-type granites, respectively. Moreover, Lan/Gdn varies between 2.45 and 5 for the S-type granite and 1.53 and 1.75 for the A-type granite. The S-type granite has been generated in a collisional zone during Assyntic Orogeny.The A-type granite, however, is formed in a within-plate environment.The A-type granite belongs to A1 subtype formed in a continental rifting setting. The crystallization temperatures for the S-type and the A-type granites vary from 650 to 750 ºC and 800 to 850 ºC،respectively.

One of the most problem of human societies is, production of types of waste solid materials in different qualities and quantities and its discharge. Discharge is the simplest method and in many reigns is low –cost method of discharge. Main goal of discharge is secure and long lasting of solid waste material discharge regard to health and environment. Selecting of place of landfill is one of the important stage in management of urban solid wastes. According to destructive environmental effects, economic and ecological of land fill, and choice of landfill should be fulfilled carefully. This research is done for this purpose to determining proper places of urban waste disposal of Mianeh city by using of hierarchical method (AHP). The current place of urban waste disposal of Mianeh city located at 13 kilometer distance in west of city and adjacent to Mianeh_Hashtrud road on the hills of Dashkasan regions with 3 kilometers motorable track and it becomes asphalt way after 10 kilometers. In this research, criteria and conditions of selecting proper places are identified for healthy landfill of waste disposals such as geology characteristic, availability ways, slop map, faults, land use map, distance of rural and urban centers, soil map of region, hydro-graphy drainage map, groundwaters and gas pipeline ways. For providing talented ability exclusion zones are deleted at first and by using of twelve information layers by weighting method to each ones and analyzing of these weights in GIS environment map obtain different criterion, then best places were selected by combination of these maps. These places located in north, northeast, southwest and southeast. From received regions, the best place is recognized and after field review, this area was confirmed final. This area is located in 8 kilometers of north and northeast and in adjacent to Mianeh _Tark and it has 2 Kilometer motorable track and after 6 kilometer. The lithology of this area mainly include marls and sandstone. It is Also, outside of Aquifer limit, and it is suitable from rural regions.

Mahneshan­­–­­Mianeh Cenozoic basin, in southern part of SE­–­­termination of North Tabriz Fault, is located between two distinct NW and N Iran tectonic domains affected by different Quaternary tectonic and stress regimes, with a transitional boundary. Determining the Quaternary state of stress in the area of interest is a key to locate the locus of this transition between the two tectonic domains. In this study, Quaternary stress state of the area was studied using the inversion of fault kinematics data (with well-known sense and chronology) measured in 25 sites in the Mahneshan­­–­­Mianeh Cenozoic basin. Our results indicate a homogenous modern compressional stress field characterized by a NE-trending horizontal maximum stress axis (~N055) prevailing through Quaternary, and coherent with the direction of the Arabia­–­Eurasia convergence in Iran.

The Siyahmansur area is located at southeastern end of the Bozgush mountain ranges in the Alborz-Azerbaijan zone. On the basis of field evidence, mineralogy and geochemistry the investigated granitoids can be classified as two types (a) Ms-granitoids, (b) alkali-granitoids. Outcropping of Ms-granite is limited to dykes and veins parallel to the metamorphic schistosity. Alkali-granitoid rocks are cropped out as a stock which is intruded in to the Cretaceous and Eocene sediments and volcanic rocks during Oligocene. Both granitoid types are deformed under strain tectonic condition and mylonite granitoids are formed in this regards. Ms-granites having peraluminous, A-type and anorogenic characteristics have been resulted from partial melting of metamorphic schists. Ms-granites recording extensive deformations are most probably emplaced under active tectonic conditions. Alkali-granitoid intrusion originated from mantle source are characterized as metaluminous and A-type granitoids. Concerning to the alkali-granitoids it seems they are emplaced due to faulting and fracturing related to decompression processes after closuring and collision of Neotethys during Alpine orogenic phase on Tertiary. On the basis of the recorded deformations on Siyahmansur alkali-granitoids it seems that they can be attributed to extrusion or escape tectonics in the intersections of southern Bozgush (Benarvan fault) and Germichai Faults.

There is a close relationship between resistance to slip along decollement surfaces and presence of deep and shallow decollement levels in thin-skinned fold and thrust wedges. Decollement units in lower (Upper Red Formation) stratigraphic levels in Mianeh-Mahneshan fold belt have an effective role onthe geometry and kinematics of deformation of the area. In order to understand the fold geometry and folding mechanisms, and to exploredepth-to-the-decollement surface, we carried out data collection and field study in an area between Mianeh and Mahneshan cities. Folded structures in the study area are different other structures within the area, as well as the structures in the neighboring Alborz Mountains.The rise of salt domes along with the plasticity of marls in the Upper Red Formation have resulted in extreme complexities in folding pattern. In order to analyze syn-sedimentary structural features and interpret the geological evolution of the area, we used detailed structural measurements, sedimentological and sedimentary environment features, sedimentary rock studies, and paleogeography.One of the results of this study was the interpretation of syn-sedimentary growth structures in the Mianeh-Mahneshan area, which helped us to construct six structural cross-sections (AA’, BB’, CC’, DD’, EE’ and FF’)across the folded structures. Measured shortening along two Sections AA’ and DD’is 46.65% and 38.05%, respectively, with an average of 42.3%. These values are different those estimated forthe neighboring Alborz and Zagros Orogens, shortening ranges between 16-30%. We attribute this difference to local intense shortening in the study area caused by several factors such as basin slope, deep faults and weak beds along decollement surfaces. This study indicates that dominant folding mechanisms in the study area are detachment folding, and fault-propagation or fault-bend folding. The presence of evaporitic material (gypsum and salt) within the succession has played a major role in the kinematics of folding.

The Siyahmansour area is located between longitude 370 46 07" to 370 50 19" N and latitude 470 53 13" to 470 58 22" E in northeastern town of Miyaneh Exposure of different igneous rocks in the studied area including Eocene to Miocene volcanic rocks, granitoids and diorites. The granitoids are different including muscovite granites and granite-granodiorite. The muscovite granites are intruded into metamorphic rocks only as dykes. The intrusion age of these muscovite granitoid types could be related to the Precambrian (?) or Early Cimmerian (?) age of the metamorphic rocks. The granite-granodiorites, including alkali-feldespar granites and granodiorites, are intruded into the Cretaceous and Eocene volcano-sedimentary rocks. The geochemistry of variety of granitoids in the studied area indicate that in the view of aluminum saturation index, the muscovite granites and granite-granodiorite are peraluminous to metaluminous respectively. Magmatic series of muscovite granites and granite-granodiorite are determined as calc-alkaline and alkaline respectively. On the basis of mineralogy and geochemical evidences, the muscovite granites and granite-granodiorite are S-type and A-type (A1 subgroup) granitoids. Tectonic setting and petrogenesis of the granite-granodiorite are determined as anorogenic within plate granitoids having mantelic origin but the muscovite granites correspond to the Syn-COLG. REE diagrams of granite-granodiorite show high enrichment of LREE relative to HREE. This indicates that they are likely generated from an enriched source, although crustal contamination and/or fractional crystallization processes can be important too. REE amounts of the muscovite granites are relatively comparable and do not show considerable variations. The spider diagrams of A-type and S-type granitoides of Siyahmansour area are consistent with a crustal source of those rocks.