Original Research Paper
Z Boroumand; S Ghassa; M Moradian; H Abdollahi; Gh Fathabadi; K Fakhremoghadam
Abstract
In this research, the bioleaching process of mixture of sulfide and carbonate zinc and lead ore of Angouran Mine, whit local mixed mesophilic bacteria was studied. The purpose of this study was to indicate the effects of pulp density, Fe(II) concentration and initial pH in the zinc and lead bioleaching. ...
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In this research, the bioleaching process of mixture of sulfide and carbonate zinc and lead ore of Angouran Mine, whit local mixed mesophilic bacteria was studied. The purpose of this study was to indicate the effects of pulp density, Fe(II) concentration and initial pH in the zinc and lead bioleaching. In Addition, the pH and Reduction-Oxidation Potential (ORP) have been monitored and evaluated during bioleaching process. The results showed that the zinc recovery through the bioleaching process (64.4 %) was much more than the leaching without bacteria (33.56 %). The results also showed, an increase in the pulp density caused a decrease in zinc recovery, and an increase in initial pH and ferrous concentration increased the zinc recovery. On the other hand, maximum lead recovery was 1.03 %. The study of bioleaching residual showed that the lead was recrystallized as Pb5(AsO4)3Cl. However, presenting the relation between mentioned parameters and Pb recovery was impossible due to lead precipitation. The results of this research could be used for bioleaching of high-grade Pb-Zn ores.
Original Research Paper
L Fazli
Abstract
For biostratigraphy of the Gurpi Formation, three sections of Halegan well, Kuh-e-Harm and Kuh-e- Nareh were selected and sampled in south Qir, Fars province. The formation is 152m thick in Kuh-e- Harm section, 124m in Kuh-e Nareh section and 128 m in well Halegan and is mainly containing argillaceous ...
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For biostratigraphy of the Gurpi Formation, three sections of Halegan well, Kuh-e-Harm and Kuh-e- Nareh were selected and sampled in south Qir, Fars province. The formation is 152m thick in Kuh-e- Harm section, 124m in Kuh-e Nareh section and 128 m in well Halegan and is mainly containing argillaceous limestone with interbeds of limestone. In Kuh-e-Harm section and Halegan well the Gurpi Formation unconformably overlies the Ilam formation and underlies the Pabdeh Formation. In Kuh-e- Nareh, the Gurpi Formation conformably overlies Ilam Formation and unconformably underlies the Pabdeh Formation. A total of 108 samples were collected and studied from the three sections mentioned and 25 Species of planktonic foraminifera belonging to 10 genera and 3 species of benthic foraminifera were identified.
On the basis of the planktonic foraminifera the age of the Gurpi Formation was determined as Campanian to Maastrichtian in Kuh-e- Harm and Halegan well and Santonian to Maastrichtian in Kuh-e-Nareh. A few biozones differentiated here are comparable with global biozones of Caron 1985 and Wynd 1963. Based on the distribution of planktonic foraminifera 6 biozones are identified as follow:
Globotruncanita elevate Partial Range Zone .
Globotruncana ventricosa Interval Range Zone .
Radotruncana calcarata Total Range Zone .
Globotruncanella havanensis Partial Range Zone .
Globotruncana aegyptica Interval Range Zone .
Gansserina gansseri Interval Range Zone .
In Halegan well Globotruncana falsostuarti zone instead of Globotruncanella havanensis Zone and Globotruncana aegyptiaca biozone was erected by the author. This zonation can be correlated with Globotruncanita elevate Total Range Zone and Globotruncanita stuarti- pseudotextullaria varians Assemblage Zone of Wynd, 1963.
Original Research Paper
M Einali; S Alirezaei; R Bakker
Abstract
The Baghkhoshk porphyry copper system is located in the southern part of the Cenozoic Urumieh-Dokhtar magmatic belt of Iran. Mineralization in Baghkhoshk is associated with two shallow diorite-monzodiorite and granodiorite bodies that intruded the older andesitic volcanic rocks. Both intrusions are extensively ...
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The Baghkhoshk porphyry copper system is located in the southern part of the Cenozoic Urumieh-Dokhtar magmatic belt of Iran. Mineralization in Baghkhoshk is associated with two shallow diorite-monzodiorite and granodiorite bodies that intruded the older andesitic volcanic rocks. Both intrusions are extensively altered by hydrothermal fluids into potassic, phyllic, and propylitic assemblages. Mineralization occurs as quartz-sulfide stockworks as well as sulfide disseminations in both intrusions and to a lesser extent in the host volcanic rocks. Two types of quartz veinlets can be distinguished in the Baghkhoshk porphyry system: 1) quartz+ chalcopyrite+ pyrite± molybdenite veinlets (mineralized veinlets); and 2) quartz± pyrite veinlets (barren veinlets). The intrusions display distinct enrichments in large-ion lithophile elements and rare earth elements relative to high-field strength elements and heavy rare earth elements, and distinct Nb, Ta and Ti troughs that are characteristic of subduction-related magmatic arcs. On various diagrams separating tectonic settings, the intrusions plot in the continental arc domain. Three main types of fluid inclusions were identified in quartz from mineralized veinlets: low salinity (4-8 mass% NaCl equivalent), vapor-rich inclusions; high salinity (mainly in the range of 32.5-35 mass% NaCl equivalent), poly-phase inclusions; and low to moderate salinity (mainly in the range of 4-10 mass% NaCl equivalent), liquid-rich inclusions. The vapor-rich inclusions yielded homogenization temperatures ranging between 325 and 434 °C, with a mode at 380-420 °C. Laser Raman microspectroscopic analysis confirmed the presence of CO2 gas and chalcopyrite daughter crystals in the vapor-rich inclusions. The high salinity, poly-phase inclusions were homogenized to liquid at temperatures of mainly 300-375 °C. The liquid-rich inclusions were homogenized at temperatures between 150 and 384 °C, with most of the measurements falling in the range of 200-250 °C and 300-375 °C. The salinities and homogenizaion temparatures for fluid inclusions in quartz from the barren veinlets were found to be 0.5-4 mass% NaCl equivalent and 200-240 °C, respectively. The fluid inclusion data suggest that Cu was originally accommodated into the system by a hot (380-420°C), low salinity (4-8 mass% NaCl equivalent), CO2-bearing, vapor-rich or supercritical fluid. A considerable drop in temperature at constant salinity from vapor-rich to liquid-rich inclusions in the mineralized veinlets suggests that cooling was the main control on ore formation as stockworks and sulfide disseminations. In the later stages of the hydrothermal activity, low salinity, Cu-poor fluids gave rise to abundant barren veinlets consisting essentially of quartz and pyrite.
Original Research Paper
Gh Ghadami; M Poosti; F Babai
Abstract
Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts ...
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Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts of plagioclase, amphiboles and biotites. Based on geochemical data and multi elements patterns, these rocks are medium to high K calc-alkaline suite and they show LILE and LREE enriched normalized multi-element patterns, and negative Nb, Ti and Ta anomalies. Chondrite normalized REE patterns display a steep decrease from LREE to HREE without any Eu anomaly. They have higher SiO2 and Sr contents and Sr/Y and La/Yb ratios and low MgO, Y and Yb contents than the normal calc-alkaline volcanic rocks. These volcanic rocks are formed in the a subduction zone in an active margin, and showing full complete of HSA(high SiO2 adakites) characteristics. HREE and Y depleted patterns suggest the existence of garnet and amphibole as a residue in the source. The source of these rocks was probably amphibole-eclogite or garnet-amphibolite possibly generated during subduction or slab break of the Neo-Tethyan oceanic slab beneath the Central Iran microplate in Neogene.
Original Research Paper
R Samadi; N Sh; H Kawabata
Abstract
Plutonic suite of Khajeh Morad at southeast of Mashhad includes granodiorites, which are cut across by younger aplite, granitic pegmatite dykes and monzogranites. Aplites are mineralogically including quartz, feldspar (albite to orthoclase and microcline), muscovite, and accessory minerals of garnet ...
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Plutonic suite of Khajeh Morad at southeast of Mashhad includes granodiorites, which are cut across by younger aplite, granitic pegmatite dykes and monzogranites. Aplites are mineralogically including quartz, feldspar (albite to orthoclase and microcline), muscovite, and accessory minerals of garnet (almandine-spessartine), tourmaline, biotite, and ilmenite. Pegmatites are composed of quartz, feldspar (albite to oligoclase, orthoclase, and microcline), muscovite, and minor amounts of garnet (almandine-spessartine), tourmaline, ilmenite, beryl, and columbite. Based on mineralogical and geochemical evidence, Khajeh Morad pegmatites are related to Li-rare elements (RE-Li) and lithium-cesuim-tantalum (LCT) pegmatite family. According to the field evidence and whole rock geochemistry, origin of garnet-bearing aplite-pegmatite melts could be related to the S-type monzogranites, as their differentiation products at late stages, occurred in a continental collision belts.
Original Research Paper
M Hajibahrami; N Taghipour; G Ghorbani
Abstract
The Hamyerd iron deposit is located in the northeast of Semnan in the boundary of the southern Alborz and Central Iran structural zones. A sub-volcanic body of monzonite and monzodiorite composition intruded limestone and pyroclastic rocks (equivalent to the middle Eocene Karaj formation). The iron mineralization ...
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The Hamyerd iron deposit is located in the northeast of Semnan in the boundary of the southern Alborz and Central Iran structural zones. A sub-volcanic body of monzonite and monzodiorite composition intruded limestone and pyroclastic rocks (equivalent to the middle Eocene Karaj formation). The iron mineralization occurred at the contact between intrusive bodies and these sedimentary rocks. The extensive hematite content along with minor amounts of magnetite, goetite, limonite, pyrite, dolomite, barite and calcite are important characteristics of the Hamyerd ore deposit. Mineralization occurred as veins and also hematite lenses with minor magnetite content. Fluid inclusion and stable isotope (S, C and O) studies were integrated to explore the Hamyerd iron ore genesis. Petrographic studies display five types of fluid inclusions in quartz and 4 types in barite. Fluid inclusions in quartz include single-phase liquid, single-phase gas, two-phase liquid-rich, two-phase gas-rich, and three-phase (liquid-solid-gas) inclusions. Three-phase liquid-solid-gas inclusions were not detected in barite. Microtermometry studies in two-phase liquid-rich inclusions revealed homogenization temperatures of 200-250 ˚C and 100-200 ˚C, and salinities of 10-20 and 0.5-5 wt% NaCl equivalent for quartz and barite fluid inclusions, respectively. Microthermometry of halite-bearing three-phase fluid inclusions showed homogenization temperature from 200 to 350 ˚C and salinity from 30 to 40 wt% NaCl equivalent. δ34SCDT values of pyrites at Hamyerd iron deposit are in the range of 2.2 to 7.4‰. The isotopic values of barites range from 13.6‰ to 20.2‰ for δ34SCDT and 10.2‰ to 12.1‰ for δ18OVSMOW, respectively. The carbon and oxygen isotopic values of calcite are in the range of -3.4‰ to -4.5‰ and 17.7‰ to 19.1‰, respectively. Microthermometry of fluid inclusions and stable isotopes (S, O, C) at Hamyerd iron deposit suggested mixing of magmatic and meteoric fluids as origin of hydrothermal solutions. Mineralization in the Hamyerd iron deposit is probably similar to Fe-skarn deposits.
Original Research Paper
M Tajbakhshian; M.H Mahmudy; A Mahboubi; R Moussavi Harami; I Ejlali
Abstract
Hydrogeochemistry of surface and ground waters is a useful way to identify performing reactions in aquifers and also in recognizing effective natural and anthropogenic polluting factors in these sources. In order to study surface and ground waters quality of shahid Hashemi- Nejad gas refinery region, ...
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Hydrogeochemistry of surface and ground waters is a useful way to identify performing reactions in aquifers and also in recognizing effective natural and anthropogenic polluting factors in these sources. In order to study surface and ground waters quality of shahid Hashemi- Nejad gas refinery region, located 35 km south of Sarakhs town, 17 water samples were collected. Parameters of pH, temperature, electrical conductivity and total dissolved solids were measured in the field, and water samples were analyzed for major anions and cations concentrations in geochemical lab. Using Piper diagram, sodium sulfate and sodium chloride type and facies were determined for the water samples. Ca2+/Mg2+v.as Mg2+ ,Ca2+/Ca2++Mg2+v.as SO42-/SO42-+HCO3- compound diagrams, total hardness and PCO2 proved carbonates dissolution. Na+/Na++Cl-, Ca2+/Ca2++SO42-,HCO3-/Σ anions, HCO3-/SiO2 , SiO2/Na++K+-Cl-, Na++K+and SO42-+Cl-ionic ratios determined factors such as ion exchange, dissolution of Gypsum, Halite and sulfates of sodium-potassium, and weathering of carbonates and silicates as the most important effective parameters on chemical composition of water sources in this area. In Log(aCa2+/a(H+)2)andLog(aMg2+/a(H+)2) v.asLog (aNa+/a(H+)2) diagrams, which are used for specifying soluble silicate minerals in water, all water samples showed the dissolution of Kaolinite except two samples which were located at clinochlore mineral zone. Calculating saturation indices using PHREEQC software proved that Calcite and Dolomite mineral had supersaturation, Halite and Anhydrite undersaturation and Gypsum mineral supersaturation, undersaturation and equilibrium states in all samples. Schoeller and Wilcox diagrams pointed unsuitable quality for drinking and agricultural usages for these water sources. In fact, because of formations presence with high solubility that lay out in large amount of surface, water resources in this area have not suitable quality, and on the other hand shallow water level and high temperature intensify it. Based on obtained results, natural factors have major role in quality area’s water resources.
Original Research Paper
M Mirzaei; L Soheili; V Ebrahimzadeh Ardestani; A Teymorian Motlagh
Abstract
The main objective of interpretation of acquired gravity data on the Earth's surface is to determine the contrasts in density or shape/dimension of mass anomalies. Interpretation of gravity data can be done through an inversion process. In this research, a block model has been considered for the subsurface ...
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The main objective of interpretation of acquired gravity data on the Earth's surface is to determine the contrasts in density or shape/dimension of mass anomalies. Interpretation of gravity data can be done through an inversion process. In this research, a block model has been considered for the subsurface anomalous mass. By considering a constant initial density (about 2.6 gr/cm3) for all blocks and by using inversion method, distribution of density of the anomalous mass was estimated and interpreted. In this research, Occam method is used to invert 246 gravity data collected in 2007. Results of the gravity data inversion show sufficient fit between observed and calculated gravity data. Using this inversion method, distribution of density in the subsurface layers related to sediments and basement are estimated in this area. Since there is a density contrast between sedimentary layers and basement, the estimated density distribution can help to explore the lithology of formations as well as the discontinuities in them. Densities less than 2 gr/cm3 in horizontal and vertical sections obtained from the inversion are attributed to the alluviums. The depth of these sediments, which include sand, silt and clay of different percentages, is estimated to be less than about 200 m. Unequal density distribution along the layers is taken to indicate fractures. In fact, these fractures are associated with part of the Tabarteh fault in this area, which caused numerous earthquakes (but less than 5 Richters in magnitude) around the Arak and Dawood Abad cities in past years.
Original Research Paper
F Kamranzad; E Mohasel Afshar; M Mojarab; H Memarian
Abstract
Landslide is one of the natural phenomena which can cause catastrophic losses or damages in life and property each year. Hence, it is very important to recognize landslide-prone areas and apply methods to prevent or reduce slope instabilities and landslide hazard and risk. For this purpose, landslide ...
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Landslide is one of the natural phenomena which can cause catastrophic losses or damages in life and property each year. Hence, it is very important to recognize landslide-prone areas and apply methods to prevent or reduce slope instabilities and landslide hazard and risk. For this purpose, landslide hazard zonation is one of the indirect and efficient methods. This study aims to apply data-driven and AHP methods to provide a zonation map of landslide hazard potential in the Tehranprovince of Iran. First, six essential and available factors including slope, slope direction, geologic background, distance from faults, earthquake acceleration and rainfall were selected to be classified in GIS based on engineering judgment. By superposing data layers over landslide distribution map in data-driven method and expert judgment in AHP method, layers and sub-layers were weighted and combined. The landslide-hazard zonation map was then produced for each of the methods in GIS. Results showed that in data-driven method 92.9% of landslides fall into the perilous zone (i.e. hazardous and very hazardous zones) having an area of 7135.15 km2, which is 37.2% of total area of Tehran province. For the AHP method, 96.47% of the landslides were in perilous zone with an area of 10344.7 km2, which is 53.9% of the total area of the province. Finally, the ratio of percentage of landslides in the perilous zone to the percentage of total area of the zone was calculated. The ratio is 2.5 for the data-driven and 1.79 for the AHP method. The larger ratio in the data-driven method indicates its better consistency than the AHP method, implying more coverage of landslides in a smaller perilous area by the data-driven method. This result represents better accuracy of the data-driven method than the AHP method in landslide hazard zonation.
Original Research Paper
A Amirpour Asl Miandoab; Q Sohrabi
Abstract
In this study, horizontal gradient and analytic signal methods have been applied to the reduced aeromagnetic data poled to Iran, to explore subsurface structures in the region. By using these two methods, it is possible to present a map of major geologic-magnetic structures especially large-scale faults ...
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In this study, horizontal gradient and analytic signal methods have been applied to the reduced aeromagnetic data poled to Iran, to explore subsurface structures in the region. By using these two methods, it is possible to present a map of major geologic-magnetic structures especially large-scale faults displaying magnetic signal in the region. Qualitative and quantitative results of this study were then prepared as maps and compared with previous studies. Finally, the agreements and disagreements observed against the previous studies were explained.
Original Research Paper
S.A Babazadeh; M Rahmati
Abstract
Carbonate sedimentary rocks equivalent to Asmari Formation containing thick and thin bedded and massive limestones with a thickness of 160m studied in Posht-Darband, Hamadan. The base of the sedimentary sequence begun with a transgressive conglomeratic horizon. This horizon is composed of rock ...
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Carbonate sedimentary rocks equivalent to Asmari Formation containing thick and thin bedded and massive limestones with a thickness of 160m studied in Posht-Darband, Hamadan. The base of the sedimentary sequence begun with a transgressive conglomeratic horizon. This horizon is composed of rock fragments such as cherts, schists and fossiliferouslimestones which are derived from adjacent old rock units. The lower contact of conglomerate horizon overlains the metamorphic rocks and the upper contact is covered by alluvium. Based on the study of thin sections from Asmari Formation, two main facies belts containing inner and middle ramps are recognized. The inner ramp composes restricted lagoon, rotalid shoal, protected lagoon and patch reef whiles the middle ramp contains proximal, middle and distal parts respectively. Based on microscopic studies, eight microfacies are presented which are consist of; 1-Large perforate foraminifera-bioclastwackestone, 2-Perforate foraminifera-red algal-bioclastpackstone/grainstone, 3-Coralgal-bioclast packstone/grainstone, 4-Coral-redalgal packstone/grainstone, 5-Imperforate foraminifera-pelloid-bioclastpackstone, 6-Rotalia grainstone, 7-Perforate-imperforate foraminifera packstone/grainstone and 8-Miliolid-bioclast-intraclast packstone. They are deposited in seven sedimentary environments. According to microfacies, this formation is distributed from tidal flat to middle ramp. The Chatian (Late Oligocene) age is attributed to these carbonate rocks based on benthic foraminifera recorded.
Original Research Paper
M Nejadhadad; B Taghipour; A.R Zarasvandi; A.R Karimzadeh Somarin; S Salamab Elahi
Abstract
Located 20 km north of the Delijan city, the Pb-Ba-Ag ore deposit was mineralized in the lower Cretaceous carbonate host rocks in the Ravanj anticline. Geographically, the Ravanj anticline is part of the Urumieh-Dokhtar magmatic arc in the Zagros orogenic belt. Deposition of the ore took place in the ...
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Located 20 km north of the Delijan city, the Pb-Ba-Ag ore deposit was mineralized in the lower Cretaceous carbonate host rocks in the Ravanj anticline. Geographically, the Ravanj anticline is part of the Urumieh-Dokhtar magmatic arc in the Zagros orogenic belt. Deposition of the ore took place in the lower part of massive limestones where they have been structurally thrusted over the shale and shale-limestone strata. Breccia filling, host rock replacement and disseminated ore are the main textural features of mineralization. Mineralization consists of fine-grained galena, barite, variable amounts of pyrite, and minor amounts of sphalerite, tetrahedrite, and chalcopyrite. Despite extensive pyritization, marcasite was not found in the ore, indicating that the ores were mineralized from a fluid having a pH > 5. Fluid inclusion microthermometric studies were done in the calcites of pre-main-stage mineralization (C2), in main-stage barite and in post-mineralization calcite (C3). Average homogenization temperatures of fluid inclusions are approximately equal: 165 ˚C in the pre- main stage calcite, 160 ˚C in post-mineralization calcite and 175 ˚C in barite, but their salinities change from lower than 1 to higher than 18wt% NaCl equivalent. Silica precipitation in the Ravanj deposit is very limited, in agreement with minor changes in temperature of fluid during mineralization. The wide range in salinity of the fluid inclusions plus contemporaneous deposition of barite and fine-grained galena are evidences for mixing of two geochemically different fluids. One of them was probably a low-salinity (5.6 wt% NaCl), CO2-beaing and sulfur-rich fluid. At a temperature of 160 ˚C, the neutral pH is about 5.8. Therefore the sulfides were deposited from fluids having a pH of 5-6. The effect of low-salinity, CO2-beaing fluid is to buffer the system. The second fluid, which was probably oxidized, saline (15.7 wt% NaCl) and metal-rich, shows salinity and homogenization temperatures characteristic of MVT ore forming fluids.
Original Research Paper
B Asadi; A Sadeghi
Abstract
For biostratigraphy of the Ilam Formation, in Surgah and Kabirkuh anticlines, 2 sections of Mehdiabad and Holostem - Poshte were selected and sampled. The thickness of the Ilam Formation in Mehdiabad and Holostem - Poshte sections are 183 and 66 meters respectively and main lithology includes limestone, ...
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For biostratigraphy of the Ilam Formation, in Surgah and Kabirkuh anticlines, 2 sections of Mehdiabad and Holostem - Poshte were selected and sampled. The thickness of the Ilam Formation in Mehdiabad and Holostem - Poshte sections are 183 and 66 meters respectively and main lithology includes limestone, shale and argillaceous limestones with intercalation of shale. The lower and upper boundaries of the Ilam Formation with Surgah and Gurpi formations are conformable with sharp lithology changes. For biostratigraphic studies 36, species belong to 15 genus of formaminifera were recognized and 4 biozones based on Premoli Silva &Verga (2004) biozonation were identified. These include:
1. Dicarinellaconcavata zone
2. Dicarinellaasymetrica zone
3. Globotruncanitaelevata zone
4. Globotruncanaventricosa zone
Based on these biozons, the age of the Ilam Formation in both sections is Santonian – early Middle Campanian. In this study, the Ilam Formation in Mehdiabad and Holostem – Poshteh sections were compared with type section.
Original Research Paper
V Joudaki; R Ajalloeian
Abstract
In the present case study, a thick overburden above the Ghomroud tunnel locally reaching about 600 meters plus the existence of many fault/crushed zones along the tunnel led the full-face Tunnel Boring Machine (TBM) to encounter squeezing and collapsing of materials. In parts 3 and 4 of the tunnel, a ...
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In the present case study, a thick overburden above the Ghomroud tunnel locally reaching about 600 meters plus the existence of many fault/crushed zones along the tunnel led the full-face Tunnel Boring Machine (TBM) to encounter squeezing and collapsing of materials. In parts 3 and 4 of the tunnel, a combination of these problems caused long-term and frequent pausing in digging processes (about 600 days). The plan is situated in the Sanandaj-Sirjan geological zone. Because of intense tectonic deformations through time, this zone consists of series of rock units, which have experienced moderate to high metamorphisms that caused schistosity and recrystallization of minerals. In the present paper, in addition to preparing thin sections of rocks for microscopic studies, the role of geological conditions with an emphasis on formation petrology is investigated to explore excavation hazards along the tunnel. Hence, by traversing along the axis of the tunnel, several samples were taken from the rocks exposed on surface and from those in the tunnel. Most problems occur in the foliated Jurassic rock units and in sections where faults and relatively thick tunnel overburden (high in-situ stress) have made the geological condition unfavorable. Results show that the petrological properties (texture, mineralogy, etc.) of the extensively foliated rock masses (schist, slate, graphite schist) and their interbedding with strong units (Quartz and quartzite veins) along with other geological factors have been effective on the occurrence of hazards and TBM pausing. Results of Cerchar abrasiveness index test also indicate high hardness and strength of quartzite veins, which played an important role in creating mixed face conditions and amplifying the hazards in easily squeezing and collapsing materials.
Original Research Paper
M Vahidinia; M Vahdati Rad; A Sadeghi
Abstract
Planktonic foraminifera of the Khangiran Formation that represents the last marine deposits in the Kopeh-Dagh basin and exposed in the Chehel-Kaman synclinal entrance (west of Sarakhs) studied in this article. A sum of 32 species belonging to 11 genera of planktonic foraminifera were recorded allowing ...
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Planktonic foraminifera of the Khangiran Formation that represents the last marine deposits in the Kopeh-Dagh basin and exposed in the Chehel-Kaman synclinal entrance (west of Sarakhs) studied in this article. A sum of 32 species belonging to 11 genera of planktonic foraminifera were recorded allowing erection of seven biozones from E4 ـ E11.indicating an age ofYpresian-Lutetian for this Formation. Based on the statistical analysis of planktonic foraminifera of the Khangiran Formation, the low and common abundances of Subbotina genus and its rare of appearance and disappearance in the upper samples of the formation and the low abundance of Catapsydrax and Parasubbotina genera and the high abundance of Acarinina genus throughout this formation indicate a warm water and intermediate trophic conditions for the depositional course of this formation in this basin.
Original Research Paper
S Ranjbar; S.M Tabatabaei manesh; M.A Mackizadeh
Abstract
The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into ...
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The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into two subzones: endoskarn and exoskarn. There is no significant mineralization in relation to this skarn system. The extent of the endoskarn subzone is very limited (often from 2 mm to 2 cm), but the exoskarn has the most extension across the contact. The endoskarn subzone can be recognized by formation of euhedral garnets adjacent to the carbonate part. In the immediate vicinity of the endoskarn, the exoskarn subzone initiates with formation of garnet and clinopyroxene in the carbonates and is extended far away from the contact as represented by vesuvianite and phlogopite minerals. Garnet is one of the most abundant minerals in this skarn system and is found in different sizes and forms. In this paper, the zonation pattern of garnet crystals in the exoskarn subzone in the immediate vicinity of intrusive body is investigated. These garnets are mainly euhedral and isotropic and in some cases anhedral and anisotropic. They are commonly cored by a grossular-rich inner part, and a sharp considerable increase in their andradite content is found toward the rim in most cases. Most studies on skarn systems consider boiling to be the most important cause for this phenomenon. This means that boiling increases the Fe content and oxygen fugacity in the final stages of the system evolution, which consequently increases the andradite content of garnet in its solid solution
Original Research Paper
E Tavakolian; A Yassaghi
Abstract
The Zagros fold-thrust belt has been cut out by various transverse faults with segments displaying en-echelon pattern. Depending on the type of overlapping and fault mechanisms, restraining and releasing zones have been developed between these en-echelon segments. The NW-trending dextral Sabzpushan fault ...
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The Zagros fold-thrust belt has been cut out by various transverse faults with segments displaying en-echelon pattern. Depending on the type of overlapping and fault mechanisms, restraining and releasing zones have been developed between these en-echelon segments. The NW-trending dextral Sabzpushan fault is one of these transverse strike-slip faults located in the Fars province of the Zagros belt. Since the Sabzpushan fault zone consists of several en-echelon segments of clockwise pattern, restraining zones have been generated between them. One of these restraining zones is developed on the NW nose of the Chaghal anticline. Detailed field studies and interpretation of satellite images resulted in identification of several dextral en-echelon faults in the western part of the Chaghal anticline. This fault zone consists of two en-echelon faults called Qir and Harm. Different kinds of structures such as dextral faults with reverse component, thrust faults, minor duplexes and young minor folds were mapped in these restraining zones. These structural assemblages are similar to those that are developed in the restraining zones produced in physical models of en-echelon strike-slip faults. In addition, similar restraining zones which are also observed across the Ghol Ghol and Sefidar anticlines to the south and north of the Chaghal anticline, respectively, are attributed to other en-echelon segments of clockwise array along the Sabzpushan fault zone. These dextral en-echelon faults along the Sabzpushan fault, which are interpreted as surface ruptures in the sedimentary cover with basal detachment zone, formed as a result of the activity of Sabzpushan fault in the basement.
Original Research Paper
H Seif; M Majidifard; T Mohtat
Abstract
The Farrokhi formation in 15 km southwest of Khur with a thickness of up to 117m consists of marl and limestone with Maastrichtian age. In this section, the Farrokhi formation disconformably overlies the Haftoman formation below and the Chupanan formation above. In the present study, 87 genera and 103 ...
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The Farrokhi formation in 15 km southwest of Khur with a thickness of up to 117m consists of marl and limestone with Maastrichtian age. In this section, the Farrokhi formation disconformably overlies the Haftoman formation below and the Chupanan formation above. In the present study, 87 genera and 103 species have been recognized. Based on foraminifera, the Farrokhi formation ranges from the Maastrichtian and 3 biozones in the rock unit 1 of the formation have been recognized: (1) Contusotruncana contuse Partial range zone (CF6), indexing Early Maastrichtian.(2) Pseudotextularia intermedia Partial range zone (CF5), index for late Early Maastrichtian index and (3) Racemiguembelin fructicosa Taxon Range Zone (CF4), an index for early Late maastrichtian. The Farrokhi formation can be subdivided into four rock units which are composed of marl and marly limestone. In addition, the Farrokhi formation fauna contains ostracods and high abundance of invertebrate as diverse species of brachiopods, echinoderms and bivalves with rare fragments of ammonites. The K/Pg boundary is in this section paraconform and can be compared with boundary of the Farrokhi and Chupanan formations. The evidence of paraconformity is a gap of Early Paleocene and changes in lithfacies. The Farrokhi formation is carbonate and it is parts of a carbonate system consisting of a platform and the adjacent slope.
Original Research Paper
S Angornai; H Memarian; M Shariat Panahi; M.J Bolourchi
Abstract
Land subsidence is an environmental phenomenon that involves gradual or sudden settlement of the land surface because of compaction of underground material. Groundwater withdrawal, which occurs due to excessive use of water resources, is among the most important reasons for this phenomenon. Therefore, ...
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Land subsidence is an environmental phenomenon that involves gradual or sudden settlement of the land surface because of compaction of underground material. Groundwater withdrawal, which occurs due to excessive use of water resources, is among the most important reasons for this phenomenon. Therefore, land subsidence can lead to destructive results in residential, industrial and agricultural areas. As a result, subsidence caused by excessive use of groundwater resources has occurred in many countries in the world. Tehran metropolitan plain in Iran is one of the most obvious examples, where land subsidence is happening. Although the relationship between land subsidence, groundwater level decline and changes in the physical properties of subsurface material is broadly understood, a comprehensive and precise model to predict land subsidence remains unconstrained. Land subsidence modeling is a complicated matter in geological engineering but can help to better understand subsidence and possibly prevent damages. The commonly used numerical methods for modeling land subsidence are generally based on simple assumptions, which make the model results to be associated with some errors. In this study, artificial intelligent methods such as Artificial Neural Networks (ANN) were used to propose a new method to predict land subsidence. The efficiency of this method was then tested in the South Tehran plain as a case study. We have used hydrological, geotechnical, remote sensing and ambient vibrations for site effect investigations. First, the collected data was studied statistically. Then, the delay between groundwater withdrawal and subsidence was computed by genetic algorithms using available hydrographs and GPS data in a period of 27 months. Model input parameters include changes in groundwater level, natural frequency of soil, alluvial thickness, defined geographic coordinates and time. The model output was an estimated subsidence measured by radar interferometry method. The model was built in 15 time steps using a set of data having 4 months of time difference with the data used to create the model. The comparison between the predicted (modeled) and real (measured by remote sensing) subsidence shows a good correlation, which makes the proposed model reliable.
Original Research Paper
M Boveiri Konari; E Rastad; M Rastad; A Nakini; M Haghdoost
Abstract
Tappehsorkh Zn-Pb-(Ag) deposit, hosted by Lower Cretaceous siltstone, tuff and dolomite, is located in the northern part of the Irankuh mountain range, south of Esfahan. Sulphides in this ore have a relatively simple mineralogy including sphalerite, galena, tetrahedrite, pyrite and to a lesser extent, ...
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Tappehsorkh Zn-Pb-(Ag) deposit, hosted by Lower Cretaceous siltstone, tuff and dolomite, is located in the northern part of the Irankuh mountain range, south of Esfahan. Sulphides in this ore have a relatively simple mineralogy including sphalerite, galena, tetrahedrite, pyrite and to a lesser extent, chalcopyrite, marcasite and bornite. Gangue minerals are predominantly dolomite, quartz and barite. Based on zoning in the sulphide mineralization, texture and structure and location of ore facies relative to syn-sedimentary normal faults, theses ore facies are classified as vein-veinlet, laminated and massive. Dolomitic-silicic alteration is among the major processes concomitant with sulphide mineralization. The greatest degrees of alteration and related ore mineralization occur at the vicinity of the normal faults and decrease away from it. Geochemical studies indicate that the ore-bearing fluids were of oxidized composition, which were reduced once reaching favorable host rocks and consequently deposited sulphide minerals. Minor and trace element studies in the various sulfide ore facies demonstrate that the ore-bearing fluid in all the ore facies has a similar composition. Textures such as framboidal pyrite, contemporaneous folding of organic matter along with sulphide lamination in the laminated ore facies, and diagenetic structures such as load casts in the host siltstone indicate that sulphide mineralization has occurred in the sedimentary-diagenetic stage. However, sulphide mineralization in the regional dolomite is considered to have occurred in a shallow diagenetic environment because of replacement of regional dolomite by hydrothermal dolomite. Based on features of ore mineralization such as the extensional tectonic setting, siltstone and carbonate host rocks, and occurrence of various sulphide facies such as vein-veinlet, laminated and massive, the Tappehsorkh deposit is very similar to Sedex-type deposits.
Original Research Paper
M Shahraki; M.H Mahmudy Gharaie; R Moussavi-Harami; A Ahmadi
Abstract
In this research the catchment of the Sarbaz river, SE Iran, has been studied to determine sediment provenance and its possible pollution potential. 30 sediment samples collected from the riverbed were analyzed for major and trace elements, using combined XRF and AAS methods. Based on major and trace ...
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In this research the catchment of the Sarbaz river, SE Iran, has been studied to determine sediment provenance and its possible pollution potential. 30 sediment samples collected from the riverbed were analyzed for major and trace elements, using combined XRF and AAS methods. Based on major and trace element data and identification charts the sediments are identified to be of litharenite composition. Quartz-rich sedimentary and intermediate igneous origin and island arc tectonic setting is proposed for the sediments, mainly inferred from discrimination diagrams. Regarding the hazardous potential of metals and metalloids, As, Cd, Co, Cr, Cu, Fe, Mn, Hg, Ni, Pb, Se, V and Zn were studied from 30 locations. Pb, Cd and As concentrations measured respectively in 7, 10 and 20 locations are more than concentrations of the same elements in the world riverbeds. In this research, the polluted sediments were evaluated using the geo-accumulation index (Igeo). Based on this index, Cd, Pb, Zn and Cu show some degrees of pollution, while other elements are evaluated to be less pollutant. Statistic analysis show strong correlation between studied elements. Volcanic activity in north of the Makran zone can readily justify the common origin of the contaminants in the catchment of the Sarbaz river. Chromium is most probably originated from the nearby Makran ophiolites. It is concluded that geological factors have mainly been the controlling factors for the sediment pollution in the Sarbaz catchment.
Original Research Paper
M Shiea; V Chegini
Abstract
In this research, the reactions of coastline between Lengeh and Gavbandi ports in the Hormozgan Province have been investigated using Hanson and Hayes classification methods. To achieve this, the dominant hydrodynamic forces along the coasts were first explored, then the effective variables were measured. ...
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In this research, the reactions of coastline between Lengeh and Gavbandi ports in the Hormozgan Province have been investigated using Hanson and Hayes classification methods. To achieve this, the dominant hydrodynamic forces along the coasts were first explored, then the effective variables were measured. According to Hayes method, the coasts situated around the Tahoneh and Gorzeh ports, between Gorzeh and Chirouyeh, between Charak and Gorzeh ports, and around Mogham are tide-dominated (low). The coastline is of mixed-energy type (tide-dominated) in Bostaneh, Chiruyeh port and around Moghdan. According to the Hanson method, however, the coastline is wave-tide dominated in all stations.
Original Research Paper
E Taheri; P Omidi; A Taheri
Abstract
In this research, the geometric and kinematic relationships between longitudinal and transverse faults in Dasht-e bu region (northwest of Damghan, eastern Alborz belt) were studied. All the longitudinal faults (Mila, Sabur and Mahtab faults) extend along NE-SW direction, whereas the transverse faults ...
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In this research, the geometric and kinematic relationships between longitudinal and transverse faults in Dasht-e bu region (northwest of Damghan, eastern Alborz belt) were studied. All the longitudinal faults (Mila, Sabur and Mahtab faults) extend along NE-SW direction, whereas the transverse faults (Cheshmeh gholghol, north Tuyeh and Dasht-e bu faults) represent nearly N-S trending structures. The transverse faults are hangingwall tear faults which resulted from thrusting occurred on longitudinal faults. There is a geometric and kinematic relationship between the two groups of faults, so that the longitudinal faults can be considered to play the role of transfer faults for the transverse faults. Movement along the transverse faults (lateral ramps) is diminished toward their tips and is transferred to the longitudinal faults.
Original Research Paper
K Rezaeeparto; H Rahimpour Bonab; A Kadkhodaie; M Arian; E Hajikazemi
Abstract
Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed ...
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Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed these parameters in Dariyan reservoir in Salman oil field A, B, C, D and E wells. On the basis of petrographic studies classification of carbonate rocks by Dunham’s method and nomination of microfacies by Flugel’s classification was done and 7 basic microfacies have been identified: Mudstone, Mudstone to fossiliferous wackestone, Orbitolinid wackestone to packstone, Bioclast packstone to grainstone with restricted microfauna, Echinoderm wackestone to packstone, Planktonic wackestone to packstone, Mudstone to Planktonic/echinoderm wackestone, that belong to open marine sedimentary environment, shoal and lagoon. The study of vertical and lateral facies changes and comparing them with modern and ancient sedimentary environments show that Dariyan Formation in this area is deposited in a leeward mud dominated carbonate ramp. Due to numerous diagenetic processes observed in the formation, of their direct impact on the quality of the reservoir to the conclusion that micritization, cementation, compaction (mechanical), neomorphism, and pyritification to block the pores and pore through in the reservoir porosity and permeability decrease while, compaction (chemical), dolomitization, and fracture caused voids and communication between them. Finally, the porosity and permeability of the reservoir increased and led to higher quality.
Original Research Paper
H Yazdanpanah; M.M Khatib; H Nazari; E Gholami
Abstract
A model suggests the current shear, which originated about 5 Ma ago, has been accommodated by strike-slip faulting within and along the margins of the Lut area. The measured Quaternary slip rate along the Nehbandan fault system to the east and the Nayband fault system to the west margins of the Lut area ...
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A model suggests the current shear, which originated about 5 Ma ago, has been accommodated by strike-slip faulting within and along the margins of the Lut area. The measured Quaternary slip rate along the Nehbandan fault system to the east and the Nayband fault system to the west margins of the Lut area is ~ 5 and ~ 1.7±0.3 mm/year, respectively. Therefore, the observed slip rate is shown to increase from west to the east margin. This has resulted in the development of a dextral strike-slip shear system with heterogeneous slip rate across the Lut area. We have used satellite images, field observations, aeromagnetic data and analogue modeling to measure Cenozoic strain distribution and slip-rate changes in the Lut area. Results show direct linkage between deformation distribution and slip rate changes along the margins of the Lut area.
Original Research Paper
M Aghazadeh
Abstract
The Sar Cheshmeh mine, a world-class porphyry copper deposit, is located in the Kerman metallogenic zone. The rock outcrops in the deposit are Eocene basalt, basaltic andesite and andesite, Oligocene granular and porphyry granodioritic intrusions and Miocene Sar Cheshmeh granodioritic porphyry stock, ...
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The Sar Cheshmeh mine, a world-class porphyry copper deposit, is located in the Kerman metallogenic zone. The rock outcrops in the deposit are Eocene basalt, basaltic andesite and andesite, Oligocene granular and porphyry granodioritic intrusions and Miocene Sar Cheshmeh granodioritic porphyry stock, granitic late fine-grained porphyry and andesitic to dacitic hornblende, plagioclase, and biotite porphyry dykes. In the spider diagrams, studied rocks show LILE enrichment and HFSE depletion pattern similar to volcanic arc rocks. Eocene volcanic rocks and Oligocene granular and porphyry granodioritic intrusions represent typical magmas characteristics of volcanic arcs whereas Miocene intrusions and dykes have adakitic nature. The (La/Yb)N ratio in the volcanic rocks and Oligocene intrusions varies between 1-5 and 7-11 respectively, while Miocene intrusions and dykes show highest amount of this ratio(20-40). Low aboundancy of HREE in the Miocene intrusions and dykes implies that garnet have been in the source, which has been formed due to increasing crustal thickness during Oligocene and Miocene. According to U-Pb dating, the Sar Cheshmeh porphyry stock and granitic late fine grained have been emplaced in 12.97 ± 0.23 Ma and 12.37 ± 0.1 Ma respectively, while hornblende porphyry dykes has been intruded in 12.16 ± 0.8 Ma. According to trace element characteristics in zircon crystals, Miocene intrusions and dykes originated from same source. Middle Miocene intrusions and dykes have been generated in a post collisional tectonic setting from various degree partial melting of amphibolitic mafic lower crust with variable garnet.
Original Research Paper
H Hajialibeigi
Abstract
The E-W trending deep-seated Balarud fault zone is formed the part of Mountain Front Fault in north of Andimeshk. This strucutre has been separated the Lurestan zone (in North) from the Dezful Embayment (in South) that has operated as a faulted zone. Several subsurfaial and surface anticlines are affected ...
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The E-W trending deep-seated Balarud fault zone is formed the part of Mountain Front Fault in north of Andimeshk. This strucutre has been separated the Lurestan zone (in North) from the Dezful Embayment (in South) that has operated as a faulted zone. Several subsurfaial and surface anticlines are affected by this fault zone. In this paper for some of these anticlines have been drawn the cross-sections that based on well data, interpreted seismic profiles and field observations. The geometrical characteristics of these anticlines analyzed from cross-sections. The achievement of these analyses is used for distinguishing the tectonics and the deformational pattern in the Balarud fault zone. These anticlines formed by following mechanism: detachment folding, fault-propagation folding and fault-bend folding. The change of the deformational style and type of these anticlines are related to present and absence of the intermedate detachment horizons and also contorted by influence of this fault zone. These anticlines that have less 100 km lengths are En echelon arrayeh, asymmetric, disharmonic, noncylindrical, convolute folds with SW vergence and helicoidally axial surfaces. The Lurestan zone is more folded than the Dezful Embayment zone. The Balarud fault zone is a sinistral simple shear zone due to influence of strike-slip fault with E-W trending in basement. It seams the strike-slip movement sinisteral component of deap-seated fault is provided a helicoidally geometry in the study area. Different mechanism of fault-related folds of these anticlines and the results of the demonstration of the style of layer folded confirm the helicoidally geometry. Direction of fault is generally due to North and gradually become vertical to subvertical in adjacent to basement. The Balarud fault zone is an oblique footwall-ramp system with oblique convergence and the Kazerun fault zone is also another member of this system. The sinistral and dextral movements respectively, have been caused by a part of the promontory of Arabian plate between these fault zones. A transition zone is formed that the structural geology process and tectonics mechanism in duration of this ramp are different. The Balarud fault zone is not continuous, and has been displaced by many strike-slip basement involved faults. A NW-SE basement fault (α fault) as a tear fault cuts the sheet of the Balarud fault parallel to the Kabir Kuh anticline.
Original Research Paper
T Salehi; M Ghaderi; N Rashidnejad-Omran
Abstract
Gomish-Tappeh Zn-Pb-Cu (Ag) deposit is located in northwestern part of Urumieh-Dokhtar volcano-plutonic zone, 90 km southwest of Zanjan. Exposed rocks at the area include Oligo-Miocene volcano-sedimentary and sedimentary sequences as well as Pliocene dacitic subvolcanic dome, rhyodacitic volcanics and ...
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Gomish-Tappeh Zn-Pb-Cu (Ag) deposit is located in northwestern part of Urumieh-Dokhtar volcano-plutonic zone, 90 km southwest of Zanjan. Exposed rocks at the area include Oligo-Miocene volcano-sedimentary and sedimentary sequences as well as Pliocene dacitic subvolcanic dome, rhyodacitic volcanics and andesite porphyry dykes. The main mineralization at Gomish-Tappeh deposit has occurred in a steeply deeping normal fault and fracture system defined by NE-SW trend in three stages including hydrothermal breccias, silicic-sulfidic, silicic-sulfidic-carbonate veins and veinlets and late banded veins (rich in silica and specularite). Host rocks to mineralization include dacitic crystal lithic tuff, dacitic subvolcanic dome, and specifically acidic tuff. Paragenetic minerals at the deposit consist of pyrite, arsenopyrite, chalcopyrite, bornite, galena, low-Fe sphalerite, tetrahedrite, tennantite and specularite. The main alteration types at the area are silicic, silicic-sulfidic, sericitic, carbonate, argillic and propylitic. Based on element distribution and frequency patterns in the ore samples, among base metals, Zn, Pb, Cu and Ag show the highest concentrations. Average grades in the ore veins at Gomish-Tappeh deposit are: 6% Zn, 4% Pb, 2% Cu, 88 ppm Ag and 44 ppb Au. Fluid inclusion microthermometric studies on quartz crystals of the first and second stages of mineralization indicate homogenization temperatures of 260-367 °C, salinities of 9.1-16.9 wt% NaCl equiv., and approximate mineralization depth of 956 m below the paleowater table. Considering high salinity fluids and base metal contents, it is likely that base metals and silver were transported by chloride complexes. Fluid inclusion studies, hydrothermal breccias, banded-colloform-crustiform textures and amorphous silica indicate that boiling is the main factor for instability of the complexes and eventually, ore deposition.
Original Research Paper
A Malaekeh; M.R Ghasemi; S Hakimi; A Bahroudi
Abstract
The Vijehnan anticline is located to the south of the Gilan-e-Gharb, in the simply folded belt of the Zagros. For analyzing the geometry and kinematics of the anticline, we first produced a geological map using a variety of satellite imagery, published geological maps and field studies. Four structural ...
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The Vijehnan anticline is located to the south of the Gilan-e-Gharb, in the simply folded belt of the Zagros. For analyzing the geometry and kinematics of the anticline, we first produced a geological map using a variety of satellite imagery, published geological maps and field studies. Four structural cross sections (A1-A2, B1-B2, C1-C2, D1-D2) perpendicular to the fold axes are produced in AutoCAD software. To analyze the geometry and kinematics of this fold, the horizontal shortening has been calculated for two cross sections. The average shortening of these cross sections is 11 percent. Kinematics analysis of the Vijehnan anticline based on the Publet & McClay model (1996) indicated that the geometry of the anticline is of detachment fold type. This result is also confirmed by the scheme which was introduced by Jameson (1987). To ensure the accuracy of the results, aspect ratio of the fold have been used which is presented by Sattarzadeh et al. (2000). The calculation of this factor indicates that the Vijenan anticline classified as detachment fold.
Original Research Paper
F Bakhshizad; Gh Ghorbani
Abstract
The Zanjan-Takab metamorphic complex includes para- and orthogneisses, amphibolites, various types of schists and migmatites along with weakly metamorphosed, young magmatic dikes and lenses. In this study, we are focusing on the Zanjan-Takab metamorphic rocks from three regions including: 1- Almalu-Ghazi ...
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The Zanjan-Takab metamorphic complex includes para- and orthogneisses, amphibolites, various types of schists and migmatites along with weakly metamorphosed, young magmatic dikes and lenses. In this study, we are focusing on the Zanjan-Takab metamorphic rocks from three regions including: 1- Almalu-Ghazi Kandi-Alam Kandi; 2- Qare Naz-Qozlu and 3- Zaki Kandi-Barut Aghasi. Orthogneisses and migmatite leucosomes from these regions show enrichment in light REEs relative to heavy REEs and are characterized by depletion in Nb-Ta. The Almalu-Ghazi Kandi-Alam Kandi orthogneiss zircons show U-Pb ages of 491-516 Ma, but with older inherited cores. Meta-tonalite zircons from this region yield magmatic ages of 24-26 Ma. Migmatite leucosomes, paragneisses and gneissic amphibolite from Qare Naz-Qozlu contains zircons with partial melting evidences at 25-28 Ma. Nd model ages of migmatite leucosomes vary between 466 and 1629, but most of them show Ordovician and late Neoproterozoic Nd model ages (TDM). The epsilon Hf (t) values of zircon rims from migmatites are positive and their Hf model ages vary between 400 and 700 Ma. According to this study, it seems that in addition to the presence of old metamorphic rocks (~500 Ma) in the Zanjan-Takab region, there are weakly (to intensely) metamorphosed, but young (38-24 Ma) magmatic rocks in this area. Furthermore, although the Cadomian magmatism in the Zanjan-Takab region is conspicuous, but this magmatism is younger relative to other Cadomian outcrops of Iran. It seems that the exhumation of gneissic rocks and hence migmatization in this region can be related to core complex formation due to the extensional phases in the Iranian plate, resulted from roll-back of Neotethyan subducted slab beneath Iran.
Original Research Paper
T Azari; N Samani
Abstract
In recent years, the artificial neural networks (ANNs) are used as an alternative to the conventional type curve matching techniques for the determination of aquifer parameters. In this paper two multilayer perceptron networks (MLPNs) are developed for the determination of leaky confined aquifers parameters. ...
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In recent years, the artificial neural networks (ANNs) are used as an alternative to the conventional type curve matching techniques for the determination of aquifer parameters. In this paper two multilayer perceptron networks (MLPNs) are developed for the determination of leaky confined aquifers parameters. Leakage into the aquifer takes place from either the upper aquifer through the confining aquitard or the storage in the confining aquitard. The first and second networks are trained for the well functions of leaky aquifers (a) without and (b) with storage in the confining aquitard, respectively. By applying the principal component analysis (PCA) on the adopted training data sets the topology of both networks are reduced and their efficiency increased considerably. In contrast to the existing networks the topology of developed networks is fixed to (2×10×2) regardless of number of records in the pumping test data. The networks generate the match point coordinates for any individual pumping test data set. The match point coordinates are incorporated with Hantush-Jacob (1955) and Hantush (1960) analytical solutions and the aquifer parameter values are determined. The performance of the MLPNs is evaluated by three sets of real field data and their accuracy is compared with that of type curve matching techniques. The proposed MLPNs are recommended as simple and reliable alternatives to previous ANN methods and the type-curve matching techniques.
Original Research Paper
R Kohansal; M Ghorbani; S.M Pourmoafi; M Khalatbari Jafari; J Omrani; S Zolfaghari; S Soleimani
Abstract
Abstract The Forumadophiolitic rocks as a part of Iran marginal microcontinentophiolites have been situated in the western part of Sabzevarophiolite. Field study shows extrusive sequence in this area with Late Cretaceous in age. This sequence has included basaltic pillow lavas with radiolarian chert ...
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Abstract The Forumadophiolitic rocks as a part of Iran marginal microcontinentophiolites have been situated in the western part of Sabzevarophiolite. Field study shows extrusive sequence in this area with Late Cretaceous in age. This sequence has included basaltic pillow lavas with radiolarian chert related to Late Turonian-Santonian, in contrast to Coniacian- Late Campanian age, when this sequence has composed of basaltic pillow lavas in lower - middle part and various tuffs in upper part. Sheet flows, hyaloclasticbreccias and pelagic limestone are intercalations between lavas and tuffs.Abundantly, pillow lavas with phyric texture are most predominant feature contrast with sheet flows. Whereas enrichment of LILE and depletion of some HFSE (Nb, Ta) exhibit subduction environment (island arcs) for pillow lavas of Forumad, and different enrichment in LREE to HREE displays unhomogenous mantle in the generation of them; the presence of two magmatic nature in lavas (tholeiitic and calc-alkaline), their positions in tectonomagmatic diagrams and clear enrichment of Th element in Late Turonian –Santonian lavas which are generally exhibition of ophiolitic extrusive sequence in Forumad area have been generated in a supra-subduction environment and back-arc basin.
Original Research Paper
A.A Nadiri; F sadeghi Aghdam; A Asgharai Moghaddam
Abstract
This study presents an intelligence committee fuzzy logic (ICFL) model to estimate the concentration of total arsenic (III, V) in the area of the Sahand Dam basin, Iran. Because of a high concentration of arsenic (III, V) compared to WHO standard, Geolology Department of Tabriz University and East Azerbaijan ...
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This study presents an intelligence committee fuzzy logic (ICFL) model to estimate the concentration of total arsenic (III, V) in the area of the Sahand Dam basin, Iran. Because of a high concentration of arsenic (III, V) compared to WHO standard, Geolology Department of Tabriz University and East Azerbaijan Regional Water Authority have attempted to sampling and analysis of surface water and groundwater resources in the mentioned area. Hydrochemical parameters Including pH, SO42-, NO3--N, F-, Fe(II, III) and As used as input parameters for Mamdani fuzzy logic (MFL), Larsen fuzzy logic (LSL) and Sugeno fuzzy logic (SFL) to estimate arsenic concentrations. The results in train and test steps showed that all of these models have a similar fitting to the arsenic concentration data in the study area. The ICFL model was adopted to combine the output of the three single fuzzy models instead of the selecting superior single model. To reap advantage of all three models, the weighted combination of the output of fuzzy models used to create a committee fuzzy model. The mentioned model uses particles population algorithm, to obtain weight based on the output of the three fuzzy models to estimate the total arsenic concentration. The results of ICFL model shows, significant fitting improvement compare to individual fuzzy logic models.
Original Research Paper
M Sadeghian; S Shekari
Abstract
Darreh-Bagh granitoidic pluton in the northwest of Aligoodarz composed of two felsic and mafic parts, with lithological composition range from diorite to quartzdiorite, and granodiorite to leucogranite respectively. Felsic rocks have calc-alkaline and peraluminous affinity and belong to S-type and continental ...
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Darreh-Bagh granitoidic pluton in the northwest of Aligoodarz composed of two felsic and mafic parts, with lithological composition range from diorite to quartzdiorite, and granodiorite to leucogranite respectively. Felsic rocks have calc-alkaline and peraluminous affinity and belong to S-type and continental arc granitoids (CAG). The most significant characterizes of felsic part are as follows: presence of the metapelitic andalusite bearing enclaves, silica (quartz fragments which inherited from quartz vein with metamorphic origin), surmicaceous and metapasamitic enclaves and also andalusitic xenocrysts through out of the felsic part. Mafic rocks have calc-alkaline and metaluminous affinity and belong to I-type and continental arc granitoids (CAG). Based on the field observations, petrographical and geochemical characterictics, penetration of basic-intermediate magmas into late Triassic - lower Jurassic metapelites and metagraywackes caused to rise temperature up to produce a large scale contact metamorphism including andalusite hornfels and sillimanite hornfels. Intersecting the temperature of melting point of metapelites and metagraywackes resulted in producing melts with suitable composition for forming of S – type granitoid plutons. Then, the produced magma ascended to the higher levels in the upper crust and emplaced in it. Granitoid magmas emplacement are associated with low-extent contact metamorphism up to cordierite hornfels facies.
Original Research Paper
H Kamali Sarvestani; A Sadeghi; S.M Mousavian
Abstract
Coexistence between hydroid Protulophila gestroi Rovereto, 1901 and family Serpulidea have been reported from many localies in Europe (England, France, Germany,…) and Middle East (Syria) from Middle Jurassic (Bajocian) to Pliocene. In this study coexistence for the first time in Iran and second ...
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Coexistence between hydroid Protulophila gestroi Rovereto, 1901 and family Serpulidea have been reported from many localies in Europe (England, France, Germany,…) and Middle East (Syria) from Middle Jurassic (Bajocian) to Pliocene. In this study coexistence for the first time in Iran and second time in Middle East are reported. The symbiont in Debarsu formation at Haftuman region in south west of Khur city has been identified. Debarsu formation with age of Early-Middle Cenomanian contains a rich collection of coexistence hydroid Protulophila gestroi with serpulid Rotulispira at 225 m from their base.
