Y Nazari; A Abbasnejad
Abstract
The Rayen plain, which is about 1900km2 in area is considered as a part of the Lut drainage basin and is located in the southwest of Lut and eastern slopes of the HezarMountain. This plain lies at the 110km southeast of Kerman city. Geographically, it is at 57˚, 13' to 57˚, 54' eastern longitude and ...
Read More
The Rayen plain, which is about 1900km2 in area is considered as a part of the Lut drainage basin and is located in the southwest of Lut and eastern slopes of the HezarMountain. This plain lies at the 110km southeast of Kerman city. Geographically, it is at 57˚, 13' to 57˚, 54' eastern longitude and 29˚, 23' to 29˚, 52' northern latitude. The average height of this plain is about 2600m above msl. Given the location of the plain at the vicinity of the Urmiah- Dokhtar volcanic Belt and considering the role of eruptions as well as volcanic rocks and hydrothermal activities on the concentration of arsenic and the role of this element in environmental problems, this study was performed on the concentration of arsenic in groundwater. In order to determine the variations and source of arsenic, in all,29 samples were collected from the water points (springs, qanats and wells).Subsequently, the concentration of As, major cations and anions(Na+, K+, Ca2+ , Mg2+,Cl-,SO4-,HCO3-), NO3-,F-, as well as EC,TDS, alkalinity and total hardness were determined. Accordingly, isoconcentration map and correlation diagram were prepared and statistical analysis including Principal Component Analysis (PCA) and Cluster Analysis (CA)were carried out. The arsenic concentration in groundwater of this plain varies from 0.1 ppb up to 248.4 ppb with an average of 21.6 ppb. Based on the statistical analysis, arsenic concentration shows positive correlation with pH. The intrusion of hydrothermal waters into the aquifer and desorption from oxides and hydroxides of iron are considered as the main causes of high-arsenic level in some parts of this plain.
E Moosavi; M Mohajjel
Abstract
The North Esfajerd ductile shear zone is exposed in NE Golpaygan in the Sanandaj-Sirjan zone. The shear sense indicators are observed in the both outcrop and microscopic scales in this shear zone. These indicators are representing a NW striking dextral shear. The dynamic analysis and outcrop- scale indicators ...
Read More
The North Esfajerd ductile shear zone is exposed in NE Golpaygan in the Sanandaj-Sirjan zone. The shear sense indicators are observed in the both outcrop and microscopic scales in this shear zone. These indicators are representing a NW striking dextral shear. The dynamic analysis and outcrop- scale indicators of extension direction exhibit a NW extension sub-parallel to the dextral shear and a compression perpendicular to it. The relative simultaneity and parallelism between North Esfajerd ductile shear zone and North Varzaneh thrust shear zone propose the partitioning of strain components in a transpressional deformation. Regarding the geochronologic data and the angular unconformity between the middle Cretaceous and Eocene rock units, the transpressional deformation and its related mylonitization occurred during the Laramide orogeny in late Cretaceous-Paleocene. The gently dipping mylonitic foliations with dextral shear imply an incompatibility between geometry and kinematics in the North Esfajerd ductile shear zone. However, the kinematic and dynamic characteristics of the North Esfajerd ductile shear zone are accommodated with lateral extrusion of material in a dextral domain.
Parallelism between the trends of dominant stretching lineations and the second generation large scale fold axes document that the major mylonitization in the North Esfajerd shear zone occurred during the second generation deformation. These mylonitic fabrics were folded due to the third generation deformation. Two generations of crenulation cleavages, respectively in relation to two refolding events, can be recognized in this shear zone. One of the refolding events with type III interference patterns (coaxial refolding) occurred during the second stage deformation in the late Cretaceous- Paleocene interval, caused the formation of the North Esfajerd shear zone, and can be observed in an outcrop scale. The other has emerged during the third stage of deformation, probably in the post Paleocene-pre Miocene interval, folded the North Esfajerd shear zone and formed the type II (boomerang shape) interference pattern in a map scale.
saeedeh senemari; L. Fazli; M. Omrani
Abstract
Nannofossils and foraminifera planktonic have been short range stratigraphy and spread vast geographical because of that two fossils groups can be used for subdividing biostratigraphy. According to this, and due to the lack of any correlational paleontological study, the nannofossils of Gurpi Formation ...
Read More
Nannofossils and foraminifera planktonic have been short range stratigraphy and spread vast geographical because of that two fossils groups can be used for subdividing biostratigraphy. According to this, and due to the lack of any correlational paleontological study, the nannofossils of Gurpi Formation have been investigated in north of Gachsaran. This formation has been formed of marl. As a result of this study and based on the obtained nannofossils and foraminifera planktonic, the studied section is Late Santonian to Late Maastrichtian in age, that corresponding to CC16-CC26 Zones (Sissingh, 1977) and Dicarinella asymetrica- Globotruncanita elevata Zone toAbathomphalus mayaroensis Zone (James & wind, 1985).
Ghodratollah Rostami Paydar; M. Lotfi; M. Ghaderi; A. Amiri; M. Vossoughi-Abedini
Abstract
Baba-Ali and Galali iron deposits in west of Hamedan are emplaced within the Songhor volcano-sedimentary sequence of Sanandaj-Sirjan geological-structural zone. Mineralography and SEM-EDAX analyses on magnetite iron ores at both deposits for better understanding of mineralogy and crystal-chemistry of ...
Read More
Baba-Ali and Galali iron deposits in west of Hamedan are emplaced within the Songhor volcano-sedimentary sequence of Sanandaj-Sirjan geological-structural zone. Mineralography and SEM-EDAX analyses on magnetite iron ores at both deposits for better understanding of mineralogy and crystal-chemistry of the ores have shown some interesting results. Studies on concentrations of some trace elements such as V, Co, Ni, Cu, Cr, Ti, Au, PGE as well as S and P impurities in the ore indicate that only some of the primary pyrites have considerable concentrations of Pt. It seems that other generations of pyrite and magnetite are depleted in these trace elements. Late stage hydrothermal fluids that lead to mineralization of pyrite in calcite-quartz gangue veins, have also been impotant for gold mineralization and pyrite has actually acted as a favorable carrier for Au. Detection of abundant phlogopite and trace element concentration patterns at Galali iron ore have strengthened volcanogenic magnesian skarn hypothesis.
M.S Mirabedini; M Agh-Atabai
Abstract
In this research, to investigate seismic pattern and precursory properties of fractal dimensions, spatial distribution and temporal variations of correlation dimensions of epicentral, De, and temporal distribution of earthquakes, Dt, before the Baladeh-Kojour earthquake have been studied. The May 28th, ...
Read More
In this research, to investigate seismic pattern and precursory properties of fractal dimensions, spatial distribution and temporal variations of correlation dimensions of epicentral, De, and temporal distribution of earthquakes, Dt, before the Baladeh-Kojour earthquake have been studied. The May 28th, 2004, Baladeh-Kojour earthquake with Mb= 6.2 (ISC), which is one of the largest earthquake in the vicinity of Tehran, was occurred in the northern part of the Alborz mountain ranges. The spatial distribution maps show decreasing in De and Dt in the eastern part of the epicenter, which is observed at 2002 in the temporal variation plots. With respect to space-time plot, it seems that this decreasing caused by the earthquake clusters that were occurred between 2002 -2003. Investigation of seismic pattern based on spatial and temporal variations of fractal dimensions and space-time plot of earthquakes demonstrate doughnut pattern (some earthquake clusters and a lot of small events) and seismic quiescence before the main shock. The results indicate that fractal dimensions are sensitive to clustering in space and time. So, the spatial and temporal variations of these parameters can be used as a precursory phenomenon, which is caused by seismic activation and quiescence.
A. Rajabi-Harsini
Abstract
Silurian shales (Sarchahan Formation), with high volume of organic matter, are the major source rock of Dehram Group reservoir in South Pars Gas Field. Residual oil (bitumen) were seen on some parts of Kangan Formation core. According to some reports, Lower Triassic (Kangan Formation) sediments is a ...
Read More
Silurian shales (Sarchahan Formation), with high volume of organic matter, are the major source rock of Dehram Group reservoir in South Pars Gas Field. Residual oil (bitumen) were seen on some parts of Kangan Formation core. According to some reports, Lower Triassic (Kangan Formation) sediments is a possible source rock, for Kangan reservoir contents (gas and condensate). Recent geochemical study on tar and asphaltic oil of Kangan Formation (not reservoir contents), shows that these oily materials were produced from shaly and shaly- limestone layers of Kangan Formation, but due to low TOC content , poor source rock potential, and low maturity level (late diagenesis) of Kangan, this Formation is incapable of production of huge amount of gas and condensate. It seems that the produced hydrocarbons from shaly and limestone layers of Kangan Formatin, has no relation with hydrocarbons generated from Silurian shales.
M. Sadeghian; M. Sheibi; S. Badallo
Abstract
The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types ...
Read More
The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types of the pluton, are cut by the leucogranites, aplitic veins, pegmatites and gabbro-dioritic dykes. The S-type nature of the Gol-e-Zard granite is evidenced by the presence of metaplitic enclaves (surmicaceous and andalusite-sillimanite hornfels), silica enclaves, andalusite and garnet xenocrysts and silica veins relicts. The anisotropy of magnetic susceptibility (AMS) method was used to investigate the mode of emplacement. The total numbers of 868 oriented core samples were analyzed for magnetic susceptibility. The obtained mean susceptibility (Km) in µЅІ was 227, 57 and 585 for granodiorites, leucogranites and gabbrodiorite dykes, respectively. The low Km values (
E. Ashrafpour; S. Alirezaei; K.M. Ansdell
Abstract
Arghash gold district is located in the eastern Sabzevar zone. The basement of this zone consists of Precambrian metamorphosed rocks and Paleozoic-Mesozoic epicontinental sediments. The basement is covered by Upper Cretaceous ophiolitic mélange and Tertiary magmatic and sedimentary rocks. Arghash ...
Read More
Arghash gold district is located in the eastern Sabzevar zone. The basement of this zone consists of Precambrian metamorphosed rocks and Paleozoic-Mesozoic epicontinental sediments. The basement is covered by Upper Cretaceous ophiolitic mélange and Tertiary magmatic and sedimentary rocks. Arghash district includes five gold-bearing vein systems, Au-I–Au-V, and one Sb vein, occurring in Tertiary intermediate to silicic volcanic rocks, tuffs, granite, and diorite. Intensive alteration, dominated by clay minerals, is confined to 1 to 5 m from the veins. The intensive argillic alteration is bordered by irregular zones of moderate to weak argillic and propylitic alterations.
Mineralization is mostly confined to veins. Pyrite is the main sulfide mineral and includes four generations: 1) disseminated euhedral to anhedral, fine- to coarse-grained pyrite (Py-I), locally associated with minor chalcopyrite, marcasite, tetrahedrite-tennantite, and arsenopyrite; native gold grains occur in quartz associated with the pyrite; 2) framboidal pyrite (Py-II) which contains up to 960 ppm Au; 3) arsenian pyrite overgrowths (Py-III) which contain up to 1980 ppm Au; and 4) fracture-filling, anhedral, barren, late stage pyrite (Py-IV). Gold occurs as nanoparticles as well as unstable solid solutions in the framboidal and arsenian pyrite.
Homogenization temperature (Th) and salinity were measured on fluid inclusions in several quartz and calcite samples. Th varies from 186º to 357ºC, and 169º to 313ºC, and salinity from 0.2 to 5.3 and 0.7 to 1.9 wt. percent NaCl equiv. for quartz and calcite, respectively. The low salinity character of the ore forming fluid is consistent with the ore mineralogy and metal contents. The variation in salinity and Th could be explained by a combination of boiling and mixing (dilution) of a hotter and more saline fluid with a cooler and less saline fluid. These processes led to the deposition of gold in the veins. The ore mineralogy, textures, alteration, homogenization temperatures, and salinities, are typical of low-sulfidation epithermal precious metal deposits.
M.A.A Mokhtari; H Moinvaziri2; M.R Ghorbani; M Mehrpartou
Abstract
Au-Cu-Mo mineralization of Aniq-Qarachilar area is located in Arasbaran ore zone within the Qaradagh batholith. Mineralization in this area mainly includes Au-Cu-Mo bearing quartz veins within the granodiorite that cropped out in three areas include: Qarachilar (2 major veins), Zarlidareh (8 veins) and ...
Read More
Au-Cu-Mo mineralization of Aniq-Qarachilar area is located in Arasbaran ore zone within the Qaradagh batholith. Mineralization in this area mainly includes Au-Cu-Mo bearing quartz veins within the granodiorite that cropped out in three areas include: Qarachilar (2 major veins), Zarlidareh (8 veins) and Qaradareh (some narrow and short veins). Alterations around the quartz veins include sericitic and silisification that has limited development. Quartz veins have compact, boxwork and brecciated texture. Sheeted veins of quartz present in some areas especially in the Qarachilar area. Sulfide mineral content of these veins commonly less than 10 percent and includes pyrite, As- bearing pyrite, chalcopyrite, molybdenite, bornite, stibnite, sphalerite and galena. Secondary minerals include coveline, malachite, azurite and iron hydroxides. Geochemical studies and grades of elements indicate that Au, Ag, Cu and Mo have high content in quartz veins. The average grade for Au in two quartz veins in the Qarachilar area is 5.76 and 3.9 ppm. The average grade for Au in the quartz veins in the Zarlidareh area is 4.7, 3.12, 2.6, 0.45, 1.09, 1.34, 1.15 and 0.58 ppm. The highest Au grade is about 359 ppm that belongs to a quartz vein with boxwork texture in the Zarlidareh area (ZV1). Moreover, W and Bi have high concentration in some veins. There is a good correlation between Au and Ag, Mo, W and Bi. Au grades in the Qaradareh quartz veins is low, but Mo grades vary between 0.15- 1.15%. Mineralization as silisic sheeted veins within the granodioritic intrusion, low concentration of sulfide minerals within the quartz veins, limited alteration aureole, Au mineralization together with Mo mineralization and high concentrations of Bi and W and relatively good correlation of Au with Ag, Bi, W and Mo indicate that Au mineralization in the Aniq-Qarachilar area can be classified as an intrusion related gold systems.
Mahyar Yousefi; R. Gholami; A. Kamkarr-Ruhani; A. Moradzade
Abstract
In the systematic exploration plan for prospecting the mineral deposit, we can design an exploration algorithm using the modeling of known mineral occurrences. Such an algorithm is a key to recognize the area where is high probability of mineralization, reduce the risk of exploration and increases the ...
Read More
In the systematic exploration plan for prospecting the mineral deposit, we can design an exploration algorithm using the modeling of known mineral occurrences. Such an algorithm is a key to recognize the area where is high probability of mineralization, reduce the risk of exploration and increases the probability of exploration success. In this paper, we introduce an algorithm for optimizing mineral potential model and target generation in the exploration operation with focus on the gold exploration. In this way, after descriptive and conceptual modeling of gold deposit, all of the characteristics that can be used as an exploration criterion have been identified and assembled as a target model. Then, various data layers have been used to generate significant evidential maps. Then all of the evidential maps should be combined to generate mineral potential model (map) of the mineralization type sought. Recent map shows the probability location of gold mineralization as target area. Finally an algorithm has been introduced in which all of the exploration stage and methods have been identified base on priority.
A. Shemshaki; Y. Mohammadi; M. J. Bolourchi
Abstract
Based on recent research by geological survey of Iran (GSI), an extensive subsidence area was observed in Hashtgerd plain (Tehran province). The geographical position of this area is 35° 47' 45" to 35° 03' 05" N and 50° 29' 05" to 50° 54' 28" E. The maximum and mean rates of this subsidence ...
Read More
Based on recent research by geological survey of Iran (GSI), an extensive subsidence area was observed in Hashtgerd plain (Tehran province). The geographical position of this area is 35° 47' 45" to 35° 03' 05" N and 50° 29' 05" to 50° 54' 28" E. The maximum and mean rates of this subsidence are 16 and 8.4 cm per year. In general, the main aquifer of plain is composed of Kahrizak and Tehran formations. These formations are alluvium type. The Kahrizak formation consists of gravel, sand and silt. This formation scatters in north of plain. Tehran formation is composed of pebble, gravel, sand and clay in fluvial cone form. Toward the center and south of plain the amount of fine material increases. The subsidence is shown in Tehran formation only. Based on geoelectrical and well-logs data, the confined to semi confined aquifer area is recognized in south and west of Hashtgerd plain. This area is in accordance with subsidence area. In the upper part of confined aquifer we can find an unconfined aquifer. The whole of penetrated water from surface of plain recharges the unconfined aquifer. The extortion of water from confined aquifer and unconfined aquifer in north of plain has caused subsidence phenomena. The unique recharge resources of confined aquifer is unconfined aquifer in north of plain. To take notice of the position and properties of confined and unconfined aquifers in this place is very important in suitable planning and management to prevent and mitigate subsidence occurrence in future.
M. Ataei; S. H. Hoseinie
Abstract
Abrasivity, as one of the most important parameters has great influence on drilling rate. Up to now, four known methods such as "Rock Abrasiveness Index (RAI)", "Cerchar Abrasiveness Index (CAI)", "Schimazek's wear factor (F-abrasivity)" and "Bit Wear Index (BWI)" have been developed for evaluating of ...
Read More
Abrasivity, as one of the most important parameters has great influence on drilling rate. Up to now, four known methods such as "Rock Abrasiveness Index (RAI)", "Cerchar Abrasiveness Index (CAI)", "Schimazek's wear factor (F-abrasivity)" and "Bit Wear Index (BWI)" have been developed for evaluating of rock abrasivity. In this paper, abrasivity of six rock types has been studied using Schimazek's wear factor and Rock Abrasiveness Index. For this purpose, equivalent quartz content and the mean size of rock grains have been calculated using thin section of rocks. All types of rocks have been tested view pointed of compressive and tensile strength (Brazilian test) in laboratory. For evaluating of drillability of rocks, the samples have been drilled using actual percussive-rotary drilling machine. Results reveal that by increasing Schmazek's wear factor, drilling rate decreases logarithmically and by increasing Rock Abrasiveness Index, drilling rate decreases exponentially.
Y. Bayati Rad; H. Mirnejad; J. Ghalamghash
Abstract
Gol-Gohar iron mine in Sirjan with general tonnage of 1135 milion tons, is one of the most important iron sources in Iran. The main ore minerals in this ore deposit consist of magnetite and subordinate hematite. δ18O of magnetite ranges from 3.8‰ to 4.8‰, while the calculated δ18O ...
Read More
Gol-Gohar iron mine in Sirjan with general tonnage of 1135 milion tons, is one of the most important iron sources in Iran. The main ore minerals in this ore deposit consist of magnetite and subordinate hematite. δ18O of magnetite ranges from 3.8‰ to 4.8‰, while the calculated δ18O of the fluids that are in isotopic equilibrium with magnetite, varies between 10‰ and 11.3‰. Such isotopic attributes indicates that magnetite originated from magmatic fluids that were also equilibrated with sources enriched in 18O. This theory completely corresponds with the breaciated environment of Gol-Gohar ore deposit and the presence of metamorphosed sedimentary and igneous rocks with high δ18O amounts. Magnetite in Gol-Gohar iron, particularly in lower levels, is associatd with sulfide phases, so that the amount of sulfur increases with depth. The main sulfide phase in Gol-Gohar ore is pyrite that occupies the spaces between the magnetite grains and occurs as narrow veinletss. The δ34S values of pyrite (23.46‰-25‰) are similar to those of seawater sulfate (~30‰) and evaporative sulfates (10-30‰) and thus suggest pyrite originated likely from such sources. Texture and pertogrephic studies also show that sulfides were deposited after the formation of magnetite ore in Gol-Gohar.
R. Hajialioghli; A. Jahangiri; M. Moazzen; G.T.R. Droop; R. Bousquet
Abstract
The igneous rocks of Takht-e-Soleyman area in the north western Iran crop out in association with the amphibolites. The contact between igneous rocks and amphibolites is sharp. Igneous rocks in the study area are mainly granodiorite, quartz-monzodiorite and quartz-diorite. Plagioclase and hornblende ...
Read More
The igneous rocks of Takht-e-Soleyman area in the north western Iran crop out in association with the amphibolites. The contact between igneous rocks and amphibolites is sharp. Igneous rocks in the study area are mainly granodiorite, quartz-monzodiorite and quartz-diorite. Plagioclase and hornblende form dominant minerals of the igneous rocks. Titanite and epidote occur in rare amounts. Chemical compositions of the clinopyroxene, plagioclase, hornblende and titanite in quartz-diorites were analysed using EPMA.
High Mg and Si contents accompanied by low Ti at the rim composition of the analysed amphiboles can be attributed to subsolidus cooling event. Magmatic crystallisation temperature for quartz-diorites is determined based on compositions of hornblende and coexisting plagioclase. Clinopyroxene composition was used to estimate crystallization pressure of the investigated rocks in the Takab area. Estimated temperature and pressure are consistent with 820±75oC and 8 kbar, respectively. Thermometry based on Ti content of the analysed hornblende gives temperature of 760oC. On the basis of chemical compositions of the analysed clinopyroxenes, sub-alkaline and I-type natures of the quartz-diorites in the study area can be concluded.
F Behravesh; M.H Mahmudy Gharaie; F Ghassemzadeh; S Avaz Moghaddam
Abstract
Traffic dust often contains high concentrations of heavy metals and can influence on environment and human health. In this study, we tried to measure heavy metals in street dusts and soil in the city of Mashhad and sample collections were carried out at the time and location of high traffic. For the ...
Read More
Traffic dust often contains high concentrations of heavy metals and can influence on environment and human health. In this study, we tried to measure heavy metals in street dusts and soil in the city of Mashhad and sample collections were carried out at the time and location of high traffic. For the purpose of this study, twenty three samples were collected from three main paths that cover the entire city and total concentrations of five heavy metals (Ni, Zn, Pb, Cr, and Cu) were measured. The index of geo-accumulation (Igeo), Pollution index (PI) and integrated pollution index (IPI) were also calculated for the contamination levels of the metals in the city of Mashhad,. The pollution index represent that all samples are highly polluted by Pb (3.688-74.16) and most of the samples are highly polluted by Zn (1.484-7.23). However, Cu (0.678-1.945) and Ni show medium level of pollution in the samples (1.01-1.935). Chromium in all samples show low levels of contamination (0.246-0.772). Possible sources of the pollutants were assessed using Pearson correlation and principal components analysis. The results of this analysis show high concentrations of metals such as lead, copper, zinc and nickel in the soil samples as compared to UCC (Upper Continental Crust). There is a positive correlation between heavy metals of zinc and copper as well as lead and zinc, which indicate the source of these metals, can be fuels as well as powder of shoe brake of vehicles. The results of the sequential extraction procedure also imply that the elements of Ni, Zn and Pb has occurred in unstable phases (F1+F2+F3+F4), indicating their human origin. But the elements such as Cr and Cu are mainly on stable phases (F5), which represents natural origin for these two elements.
B. Shafiei; S. Lali faz; Gh. H. Shamanian; H. Taghizadeh; M. Hossaini; R. Mathur
Abstract
In present study, Re concentration determined in 30 hexagonal (2H) and trigonal (3R) molybdenite samples belong to veinlets of different stages of hypogene mineralization from 7 porphyry Cu and Mo deposits from Kerman region. Re concentration in molybdenites of these ore deposits varied from 49 ...
Read More
In present study, Re concentration determined in 30 hexagonal (2H) and trigonal (3R) molybdenite samples belong to veinlets of different stages of hypogene mineralization from 7 porphyry Cu and Mo deposits from Kerman region. Re concentration in molybdenites of these ore deposits varied from 49 g/t to 1449 g/t which are in Re concentration range of other porphyry Cu and Mo deposits around the world. In general, 3R molybdenites show the higher Re concentration (average ~ 563 g/t) than those of 2H molybdenites (average ~ 479 g/t). Variations of Re concentration in molybdenite types deposited during different stages of hypogene mineralization indicate more concentration of Re in molybdenites precipitated with transitional (B-type veins) and late (D-type veins) stages of mineralization than those of early stage veinlets (A-type veins). This distribution suggest that Re with more acidic and cooler hydrothermal fluids at the transitional and the late stages of porphyry system evolution is more concentrated with silicification, sericitization, and argillization alterations. Present study indicated that molybdenites with high Re content are associated with porphyry copper deposits which are characterized by low average grade of Mo, limited contents of molybdenite, and also their productive intrusive is resulted from significant contribution of mantle-derived magmas respect to crustal materials.In addition to abovementioned signatures, frequency of 3R poly-type of molybdenite in ore deposits, less fractionated and more calcic composition of productive intrusive of ore deposits with their less radiogenic of Sr and Pb isotope ratios, as well as occurrence of late stages of acidic and low temperature hydrothermal alteration and mineralization processes in formation and evolution history of ore deposits are signatures of porphyry copper and molybdenum deposits with high Re contents.
N Abbassi; M Parvanehnezhad Shirazi; M.A Hosseinzadeh
Abstract
Albian–Cenomanian siliciclastic-carbonate sediments of northwest Rayen in south Kerman, southeast Iran (526 m) are classifiable to three informal units. Unit one includes conglomerates, sandstones and siltstones with limestone and marl intercalations. Unit two is composed of Orbitolina bearing ...
Read More
Albian–Cenomanian siliciclastic-carbonate sediments of northwest Rayen in south Kerman, southeast Iran (526 m) are classifiable to three informal units. Unit one includes conglomerates, sandstones and siltstones with limestone and marl intercalations. Unit two is composed of Orbitolina bearing limestones with rudists, belemnoid and ammonite bioclasts. Alternations of pelagic limestones and sandstones formed the third unit. Assemblage of continental to marine trace fossils have been found in the first and third units of the studied section, that include Koilosoma isp., Ophiomorpha isp., Palaeophycus isp., Planolites isp., Skolithos isp., Taenidium isp., and Thalassinoides suevicus. These trace fossils belongs to Scoyenia, Skolithos and Cruziana ichnofacies. Abundant Thalassinoides-Phycodes compound trace fossil, however have been found in the third unit. Box-worked Thalassinoides burrow system ends to multi- branched Phycodes borrows. This compound trace fossil is interpreted as feeding-domicile biogenic structure, so that Thalassinoides domichnium ends to Phycodes excavated feeding burrows. Compound Thalassinoides-Phycodes trace fossil extended in the deeper parts of offshore shelf sediments in the studied section. Based on ichnological data, it seems that Albian–Cenomanian sediments of northwest Rayen deposited in a deepening upward sequence.
M Allameh; S Saadati Jafarabadi
Abstract
The Dalichai Formation is among marine deposits in Jurrasic period that has a geographic expansion in north of Iran. In order to palynological studies in eastern part of the BinaloudMountains an outcrop of this formation, in the bar village was selected. The thickness in bar village section is 255 meters ...
Read More
The Dalichai Formation is among marine deposits in Jurrasic period that has a geographic expansion in north of Iran. In order to palynological studies in eastern part of the BinaloudMountains an outcrop of this formation, in the bar village was selected. The thickness in bar village section is 255 meters includes dark gray shales. The study of 112 slides of 28 samples taken from this formation showed that the most of the samples contain palynomorphs specifically dinoflagellates. 53 species belonging to 27 genera of dinoflagellates were identified. According to dinoflagellates, a middle Jurassic age was determined for the Dalichai Formation in the Bar village section. Based on the study of three main groups of phytoclasts, marine palynomorphs and amorphic organic matters and result of the statistical studies of different factors, sedimentary environment of the Dalichai Formation in studied section was open marine basin with shallow and low oxygen condition.
S. Zandifar; M.V. Valizadeh; M. A. Barghi; M. R. Foroodijahromi
Abstract
The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet ...
Read More
The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet porphyroblasts in different metamorphic zones and special different sizes in the first metamorphic zone of the NE skarn, the crystal size distributions of this mineral is studied. With regard to this, digital photos of cutting surface were provided and analyzed by JMicrovision software. It has been expected, two different slopes can show three suspections: 1- parent rock composition effect; 2- crystal growing time; 3- fluid flow around plutonic rock. According to the presence of clintonite, vesuvianite and garnet and as many as joints in the region, the role of fluid in growing the size of garnet porphyroblast in part of the first metamorphic zone seem to be noticeable.
K. Shirani; A. Seif
Abstract
The landslide hazard zonation was executed by different methods and many of these methods were based on special condition of the study area. This research, at first, Pishkuh region (fereyidonshahr administration) was selected with 77646 hectars area in west of Esfahan province. Then, landslide inventory ...
Read More
The landslide hazard zonation was executed by different methods and many of these methods were based on special condition of the study area. This research, at first, Pishkuh region (fereyidonshahr administration) was selected with 77646 hectars area in west of Esfahan province. Then, landslide inventory map was obtained by using airial photos, satellite images (ETM+2002), geology maps and surveying of the field. Also, the 8 important factors are effective in occurrence of landslide including slope gradient, aspect, lithology, landuse, rainfall, and distance to fault, road and drainage were determined by using inspect of feild, literature review in similar regions of northern Karoon and Dez basins in scale of 1:50000. In order to increasing of precision, speed and facility of analysis, all of the attribute and spatial data were entered into ArcGIS software. After producing of information layers and weighting to effective factors by using inventory map, landslide hazard zonation was created by two bivariarte statistical methods including to Information value and Density area methods and the results were assessed. When the density ratios (Dr) Index (for the purpose of camparing between hazard classes) increase in each two method, then hazard rate will increase and the separation between hazard zone classes is acceptable and increasable. The quality sum (Qs) and precision (P) indices (in order to comparing of methods together) for Information value method are 0.65, 0.034 and for Density area method are 0.56, 0.028, respectively. It is clear that the information value is better than Density area in landslide hazard zonation.
Yahya Djamour
Abstract
Today, the best coordinates of stations on the ground are obtained by using Global Navigation Satellite Systems (GNSS) such as Global Positioning System (GPS). There are many error sources affecting the GNSS observations that limit the required accuracies. But differential positioning methods, like double ...
Read More
Today, the best coordinates of stations on the ground are obtained by using Global Navigation Satellite Systems (GNSS) such as Global Positioning System (GPS). There are many error sources affecting the GNSS observations that limit the required accuracies. But differential positioning methods, like double difference, are big helps to us to achieve an accuracy of millimeter. Differential operation of GNSS is based on placing a reference station with a GNSS receiver at a known location. One of such errors is the coordinate error of reference station and its propagation on unknown stations. In fact the coordinates of a reference station should be known in a reference system coordinate, such as WGS84 used in GPS, which we usually assume is exactly known. In practice, the position of the reference station in the reference system coordinate may not be exactly known due to different reasons. Therefore, in this study, the effect of the reference station position errors on various ranges from ~4 km to ~90 km, in static mode and using double difference carrier phase, is investigated. The results show this effect could be of the order of a few ppm depending on error magnitude of reference position and the range of baseline.
Z. Hosseinmardi; M. Ghorashi; M. R. Ghassemi; M. Talebian
Abstract
The outcrop of northern part of North Eshtehard Thrust has been selected for study of structural evolution and geological processes. The study area includes folding structures with different scales from regional to outcrop which belong to fault related folding category. Analysis of joints in the region ...
Read More
The outcrop of northern part of North Eshtehard Thrust has been selected for study of structural evolution and geological processes. The study area includes folding structures with different scales from regional to outcrop which belong to fault related folding category. Analysis of joints in the region among upper red formation strata shows two main sets which are usually tensional (j1 & j2). These joints are visible in sandstone units of upper red formation and most of them are filled with gypsum. It is obvious that the j1 joints are younger than j2. j1 and j2 joints are related to folding processes. The local stress field which could be measured from the joint study is σ1=337/75, σ2=189/13 and σ3=077/03 and corresponds with the given paleostress direction for southern part of central Alborz.
A Alizadeh; R Safari
Abstract
Seismic values are the main parameters in evaluating the neotectonic activity of a region. In August 11, 2011, two Mb=6.4 and Mb=6.3 earthquakes occurred in Ahar-Varzaghan region within 11 minutes. Seismotectonic investigations imply that the faults generating the events are the young faults of the regions. ...
Read More
Seismic values are the main parameters in evaluating the neotectonic activity of a region. In August 11, 2011, two Mb=6.4 and Mb=6.3 earthquakes occurred in Ahar-Varzaghan region within 11 minutes. Seismotectonic investigations imply that the faults generating the events are the young faults of the regions. Also, distribution of the epicenters represent a pattern consistent with the fault trends in the area. Temporal and spatial distribution of the earthquakes (fractal analysis) as earthquake pre-indicators together with a-b values were used toassessthe neotectonic activity and explore the seismic model of the Ahar area. Results showa sharp decrease in b-value,indicating that the main shock was associated with a zone of high strain rate. The seismic model presented for the Ahar area illustrates three periods after the main shock including: 1) an early quiescence Q1, 2) an aftershock period B, and 3) a late quiescence Q2. The rather increase in b-value during the Q2period is interpreted to indicate stress decrease in the region.
Economic Geology
Behzad Hamamipour; H. A. Tajeddin; Leila Barahmand
Abstract
The Sebandoon gold deposit is located 40 km north of the Bardaskan in the northern part of the Central Iran. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte-trachyandesite, andesibasalt,tuff and carbonaceous shale which intruded by post Eocene ...
Read More
The Sebandoon gold deposit is located 40 km north of the Bardaskan in the northern part of the Central Iran. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte-trachyandesite, andesibasalt,tuff and carbonaceous shale which intruded by post Eocene syenite-quartz monzonite subvolcanic intrusions and diabasic dikes. The main gold reservoir in the Sebandoon deposit has occurred in cone-shaped and mostly in the trachyte-trachyandesite lava with dimensions of 90×150 m in the surface which continue up to the depth of 70 m. The hydrothermal alterations occurred in the deposit area include silicic, sulphidic, partly argillic (supergen) and propylitic which two former contains most of the high grade gold ores. The main ore structures and textures in the deposit are vein-veinlets (stockwork) and breccia which consists of quartz, sulphide minerals and rare adularia. Primary ore mineral assemblages of the deposit are simple and consist of pyrite, sphalerite, chalcopyrite, bornite, galena, arsenopyrite and gold. Covellite, chalcocite and iron hydroxides are secondary minerals in the deposit. Gold grains with less of than 60 microns in size has been found as inclusion in pyrite and chalcopyrite, in sulfides rims and intergrowth with quartz. Fluid inclusion studies on ore-bearing quartz reveal that majority of primary inclusions are liquid-rich two-phase (LV). The studies indicate homogenization temperatures between 165 and 254°C and salinity between 0.9 to 7.8 wt% NaCl eq. Comparison of the main characteristics of the Sebandoon deposit with epithermal gold deposits reveals that the geology, alteration, ore mineralogy, geochemical characteristics and fluid inclusions of the Sebandoon gold deposit is similar to low to intermediate-sulphidation type epithermal deposits.
Seyed Mohsen Mortazavi
Abstract
Damavand is a stratovolcano and has power full explosive eruptions during its activity. Pyroclastic products in Damavand volcano has been mostly deposited as pyroclastic fall and flow deposits. Pyroclastic fall deposits in some locality extending up to 20 km from the summit. Damavand pyroclastic deposits ...
Read More
Damavand is a stratovolcano and has power full explosive eruptions during its activity. Pyroclastic products in Damavand volcano has been mostly deposited as pyroclastic fall and flow deposits. Pyroclastic fall deposits in some locality extending up to 20 km from the summit. Damavand pyroclastic deposits cover much of the eastern and southern flanks of the volcano suggested that during the eruption, tephra dispersal axes was toward to the east. There are a major young pumice deposits, named as Karam Poshteh pumices, are identified and consists of a coarse-grained pumice fall deposit with proximal welded facies dispersed to the west, but lacks pyroclastic flow deposits with provisional ages in the interval >7.3 ka and < 25 ka.This young pumice fall deposit is distributed over much of the western and south-western flanks and is located at the foot of the steep Damavand cone at the mouth of a ravine where the proximal welded facies is well exposed on the ravine walls. The deposit can be divided into thin more distal unconsolidated pumice fall deposits and think proximal welded pumice fall deposits. Karam poshteh deposits also consist of welded beds of pale pink pumice with minor cross-layered ash beds. Atmospheric information, in particular wind data, is crucial in order to perform tephra dispersal simulations. Tephra transport and sedimentation is controlled by wind in the atmosphere and is a function of wind velocity and provenance for tropospheric and stratospheric levels. Mehrabad meteorological station is supplied wind data at different altitudes. We apply and intemperate wind data between 1995 to 2010 at Damavand volcano to understand regional distribution of tephra fall. Westerly winds are persistent during winter and summer time at troposphere. The most prominent features in the stratospheric circulation are a westerly jet in the winter hemisphere and low velocity easterly jet in the summer hemisphere. Easterly jet in the summer implies that Westward transport of tephra in Karam poshteh.
