Editor-in-Chief Lecture
Volume 26, Issue 103 , June 2017, Pages 1-1
Reviewers
Volume 26, Issue 103 , June 2017, Pages 2-2
Original Research Paper
Stratigraphy and Palaeontology
M. Allameh; A. Mahboubi; R. Moussavi-Harami; M. Khanehbad
Abstract
The Aitamir Formation (Albian-Cenomanian) composed of siliciclastic rocks and several carbonate horizons. In order to study depositional environment and sequence stratigraghy, two stratigraghic sections studied in east Koppeht Dagh basin near the Baghak and Shurijeh villages. Field and petrograghic studies ...
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The Aitamir Formation (Albian-Cenomanian) composed of siliciclastic rocks and several carbonate horizons. In order to study depositional environment and sequence stratigraghy, two stratigraghic sections studied in east Koppeht Dagh basin near the Baghak and Shurijeh villages. Field and petrograghic studies led to siliciclastic and carbonate facies that deposited in lagoon, barrier, shoreface and open marine environments. Sequence stratigraghy analysis led to identification of three depositional sequences in both sections. Comparision of interpreted sea level curves at studied area with Albian-Cenomanian global curve shows similarities and differences that can be relatedto tectonic setting and sedimentation rate.
Original Research Paper
Economic Geology
S. Maghfouri; M. R. Hosseinzadeh; A. Rajabi; A. M. Azimzadeh
Abstract
Darreh-Zanjir Zn-Pb deposit is located at the south of Taft city. Sulfide minerals in this deposit include sphalerite, galena and pyrite. Replacement, open space filling, vein-veinlet, breccia and massive are the typical textures in the Darreh-Zanjir deposit. Mineralization is associated with normal ...
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Darreh-Zanjir Zn-Pb deposit is located at the south of Taft city. Sulfide minerals in this deposit include sphalerite, galena and pyrite. Replacement, open space filling, vein-veinlet, breccia and massive are the typical textures in the Darreh-Zanjir deposit. Mineralization is associated with normal fault. Gange mineral is dolomite and dolomitization is related to mineralization. Three types of dolomite have been recognized in the Darreh-Zanjir region: 1- Regional dolomite, formed during diagenesis of micritic limestone of the Taft formations and is exposed in whole region. It has dark gray color and fine crystals. 2- Thrusting dolomite, formed during compression and thrusting of the Taft formation on the Darreh-Zanjir formation, this dolomites are located at the vicinity of thrust fault.3- Mineralization and dolomitization occur adjacent to normal fault. This dolomite is known as hydrothermal dolomite (DH) and it decreases away from of sulfide mineralization. Geochemical studies suggest that high content of cadmium in sphalerites represents low temperature for ore forming fluid. Supergene and oxidation process caused change of sulfide minerals to non-sulfide minerals. Non-sulfide minerals of the Darreh-Zanjir deposit are smithsonite, hemimorphite, hydrozincite, cerrusite and Fe-oxides and hydroxides. The most important characteristics of mineralization at the Darrh-Zanjir deposit such as tectonic setting, post compression of normal fault controlling mineralization, host rocks, mineralogy, metal content as well as wall textures, show similarities with Mississippi Valley-type (MVT) Zn-Pb deposits.
Original Research Paper
Exploration and Mining
V. Joudaki; F. Koohiyan-Afzal; A. Aalianvari; R. Ajalloeian; A. Sohrabi-Bidar
Abstract
Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some ...
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Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some limitations such as thick(up to 600 meters in some localities)overburden over the tunnel and the lack of exploratory drilling down to the tunnel level, it has been difficult to forecast and estimate the groundwater flow in the tunnel route. Due to the existence of numerous faults in part 4 of the Ghomroud tunnel ,encountering of the drilling machine (Double Shield TBM) with high-pressure water could cause influx of large amounts of water into the tunnel and collapse of rock masses in the crushed zones. It hence could cause deviation of the machine and drilling stop. In this article, the lack of data from boreholes led us to try investigating the development of groundwater flow in the tunnel based on geomorphological evidence. Analytical modeling and geomorphological field survey in the area show a relative consistency between geomorphology and volume of water flowing in the tunnel excavation. Therefore, according to measurements conducted on the water entering the tunnel, about 80 liters per second of water flowed into the tunnel, which is in agreement with geomorphological studies. Results show that the study of morphology and surface features could provide useful information in order to identify more precisely the hydrogeologic conditions of the area.
Original Research Paper
Petrology
M. Sadeghian; S. H. Hosseini; A. Hemmati; S. Shekari
Abstract
Granitoid plutons of SW Mayamey (60 Km east of Shahrood), located at the most northern margin of the central Iran structural zone, have granite composition (in general) and calk alkaline and peralouminous nature. In spite of coverage of these granitoids by Late Triassic – Early Jurassic sedimentary ...
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Granitoid plutons of SW Mayamey (60 Km east of Shahrood), located at the most northern margin of the central Iran structural zone, have granite composition (in general) and calk alkaline and peralouminous nature. In spite of coverage of these granitoids by Late Triassic – Early Jurassic sedimentary rocks, Late Neoproterozoic host gneiss are exposed in limited areas. These granitoids invaded by two series of the Late Neoproterozoic and middle Jurassic diabasic dikes. Although post – Liass, Pre- Dogger, younger than Jurassic and older than Cretaceous ages are considered for these granitoids, but for the first time U–Pb age dating on separated zircons indicates Late Neoproterozoic age (Late Ediacaran) (545±10 Ma) for them and they are a part of very ancient basement rocks of Iran. The studied rocks are similar Band -e-Hezar Chah, Sefid Sang, Delbar, Shotor Kuh, Reza Abad and Do Chah granitoids in age. Mayamey granitoids are resulted from partial melting of metapelites and metagraywackes, and they belong to S-type granioids. SW Mayamey granitoids were generated in a collisional tectonic setting in the Late Neoproterozoic, in relation to closing of intracontinental back arc basin and then metamorphism of the associated rocks from greenschist facies to amphibolite and rarely granulite facies, which finally companied with s-type granitization
Original Research Paper
Sedimentology
A. Rahimi; M. H. Adabi; A. Nabati; M. R. Majidifard; A. M. Jamali
Abstract
Carbonate sequences of the Shotori Formations (Middle Triassic) with a thickness of 308 m, were deposited in the Kalmard region of the Tabas city in Central Iran basin. The lower contact of the formation gradually and conformably overlies the Sorkhshale Formation and upper contact is faulted. The Shotori ...
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Carbonate sequences of the Shotori Formations (Middle Triassic) with a thickness of 308 m, were deposited in the Kalmard region of the Tabas city in Central Iran basin. The lower contact of the formation gradually and conformably overlies the Sorkhshale Formation and upper contact is faulted. The Shotori Formation is mainly composed of thick to medium bedded fine-coarsely crystalline dolomites with a thickness of 250 m with interbeds of thin bedded limestone and sandstone. The Shotori Formation is mainly composed of fine-coarsely crystalline dolomite. Based on petrographic (size and fabric), and elemental studies (Ca, Mg, Na, Sr, Fe, Mn), five dolomite types were recognized. Variation in dolomite types is mainly related to early to late diagenetic processes, changing the composition of dolomitizing fluids. Geochemical studies also indicate that medium to coarse grain dolomites formed in meteoric diagenesis under reducing conditions. Mechanism of dolomitization for dolomite type 1 is sabkha model, for dolomite types 2 and 3 is mixing zone and is burial model for dolomite types 4 and 5.
Original Research Paper
Economic Geology
S. Amani Lari; I. Rassa; A. Amiri
Abstract
Ahmadabad Zn-Pb deposit is one of the Pb-Zn deposits in the Kouhbanan-Bahabad metollogeny Belt, which is located 10th Km northwest of Bahabad City in the Posht-Badam Block in Centeral Iran Zone. Ore deposits consist of Zn, Pn, Mo and Sr non-sulfide minerals with large amount of Fe oxide-hydroxide ...
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Ahmadabad Zn-Pb deposit is one of the Pb-Zn deposits in the Kouhbanan-Bahabad metollogeny Belt, which is located 10th Km northwest of Bahabad City in the Posht-Badam Block in Centeral Iran Zone. Ore deposits consist of Zn, Pn, Mo and Sr non-sulfide minerals with large amount of Fe oxide-hydroxide minerals occurred in dolomitic host rock of the Shotori Formation. A quartz-calcite vein accompanies ores in the host rock. This study is focused on C-O isotopic variation in the host rock, quartz-calcite vein and hydrozincite. Isotopic variation of C indicates that the source of carbon is different in the host rock and quartz-calcite vein. The most important source of carbon for hydrozincite formation was carbonate rocks of the area and regarding this aspect this deposit is different from others Zn-Pb non-sulfide deposits that studied in the world. According to oxygen isotopic variation, the temperature for hydrozincite formation was between 14-44˚C. The oxygen isotopic variation suggests marine basin water as the source of quartz-calcite vein. The dolomitic host rock was formed in equilibrium with fluids of a mixture of marine and magmatic waters, based on oxygen isotopic variation.
Original Research Paper
Economic Geology
R. Amirkhani; M. Ebrahimi; M. A. A. Mokhtari; A. M. Azimzadeh
Abstract
The study area which is introduced as Homeijan magnetite- apatite mineralization in this paper, is a part of the Posht-e-Badam block in the Central Iranian Zone and is located at ~12Km southwest of Behabad. This area is composed of volcano-sedimentary rocks and acidic- basic intrusions of Precambrian ...
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The study area which is introduced as Homeijan magnetite- apatite mineralization in this paper, is a part of the Posht-e-Badam block in the Central Iranian Zone and is located at ~12Km southwest of Behabad. This area is composed of volcano-sedimentary rocks and acidic- basic intrusions of Precambrian and Cambrian age. Magnetite- apatite mineralizations are present as lenses near the southwestern part of the Homeijan village, which are hosted by acidic- intermediate tuffaceous rocks and dolomites. Magnetite, oligist (hematite), pyrite and chalcopyrite are the main ore minerals and apatite, pyroxene, tremolite- actinolite, calcite and quartz are as gangue minerals in the Homeijan Fe mineralization. Based on field and mineralogical studies, this mineralization texturally includes massive, brecciated, vein- veinlets and replacement textures. Chemical analyses of samples indicate that the mineralization has high concentrations of REEs up to 2.5 % in the apatite crystals. Geochemical studies demonstrate that Fet have high negative correlation with P2O5, SiO2 and ∑REE while there is a high positive correlation between ∑REE and P2O5. SEM-EDS qualitative analyses of apatite crystals indicate two REE bearing minerals including monazite and allanite as inclusions within the apatites. Furthermore, this study demonstrates that the apatite crystals are flour- apatite. Fluid inclusion studies within the apatite crystals indicate that main salinity varies between 7.86-13.9 wt.% NaCl and homogenization temperature is between 240-370°C. Comparing of REE patterns of Homeijan magnetite- apatite mineralization with other iron oxide- apatite mineralizations of Posht-e-Badam Block and Kiruna- type iron ores indicate similarities between these patterns. Generally, based on field and geochemical studies, the Homeijan magnetite- apatite mineralization classified as Kiruna- type Fe deposit.
Original Research Paper
Hydrology
A. Shemshaki; Gh. H. Karami
Abstract
The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding ...
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The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding of the changing history of the lake during the geological past. This can help to better explore the risk factors influencing the drying process of the lake. This understanding can therefore be employed to appropriate planning and management procedures in order to revive this lake effectively. Based on this study, the lake water in the levels higher than 1286 meters (MSL) is brackish to fresh and is not of saline type. Thus, it seems that, in the late Pleistocene, the lake water was of a fresh type where the water level was higher than 1297 meters. The study revealed that the lake become to a playa-type environment in water level of about 1273 MSL. The present water level of 1270 meters suggests that the lake has a dominantly playa-type environment. In this environment, increase in precipitation and inflows will lead to a rapid increase in reservoir volume; and vice versa, a stop or decrease in the precipitation and inflows with an increase of temperature and evaporation will lead to a rapid reduction in reservoir volume. This study estimates that a volume of over 9.5 billion cubic meters of water is necessary to revive the Urmia Lake.
Original Research Paper
A. Ansari; S. J. Sheikh Zakariaee; S. Dargahi; M. Arvin
Abstract
The Chargonbad batholith is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone . This batholith is acidic to intermediate in composition and intruded into the Eocene volcanic rocks. The main volume of these rocks consisted of granodiorite and monzogranite, but it also consists of ...
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The Chargonbad batholith is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone . This batholith is acidic to intermediate in composition and intruded into the Eocene volcanic rocks. The main volume of these rocks consisted of granodiorite and monzogranite, but it also consists of quartzdiorite, tonalite and syenogranite. Their contacts are gradational. They have allotrimorphic granular texture with subordinate porphyritic texture. Their enclaves consist of xenoliths enclaves, microgranular mafic enclaves (diorite to quartzdiorite in composition) and autolith enclaves(tonalite, granodiorite and monzogranite in composition).The Chargonbad batholith rocks are also cut by different types of dykes which are mainly consisted of dykes and veins of pegmatitic stage, microgranular dykes (andesite and andesite basaltic in composition) and microgranular dykes that are similar to mafic enclaves. Evidenc show that the samples represent properties of I-type granitoids. Chargonbad granitoid has magnesium nature and shows cordellarian granites features. Based on the tectonomagmatic environment diagrams, all samples from the Chahargonbad plot in the island arc setting of a subduction zone and show active continental margin setting characteristics .
Original Research Paper
N. Mousavi; J. Ebbing; V. Ebrahimzadeh Ardestani
Abstract
We apply two forward methodologies in order to study density and susceptibility structure of the crust and upper mantle. The study area is a profile crossing the Zagros collision zone located as margin of Eurasia-Arabia converging plates. Gravity modeling focusing on lithospheric structure is performed ...
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We apply two forward methodologies in order to study density and susceptibility structure of the crust and upper mantle. The study area is a profile crossing the Zagros collision zone located as margin of Eurasia-Arabia converging plates. Gravity modeling focusing on lithospheric structure is performed in thermodynamic framework in which chemical composition is important and provides an understanding of deep layers in lithosphere like Moho and Lithosphere-Asthenosphere Boundary. Results on the crustal thickness show minimum values beneath the Arabia Platform and Central Iran (42–43 km), and maximum values beneath the Sanandaj Sirjan zone (SSZ; 55–63 km). Results on the lithosphere thickness a long profile also indicate that the Arabian lithosphere is approximately 220 km thick, toward North West of Iran especially below the Central Iran rises up to 90 km. In the profile (central Zagros), lithosphere thinning occurs in wider region, from the Zagros fold thrust belt to the Sanandaj Sirjan zone. Our results are based on application of average Proterozoic mantle compositions in modeling beneath the Arabian Platform, Mesopotamian Foreland Basin and Iranian Plateau. After rough estimation of upper crust via integrated modeling by elevation, gravity and geoid data, the distribution of density and magnetic susceptibility values allows us to perform a study in crustal scale. Afterwards, determination of the homogenous blocks with the same density and susceptibility, the geometry to different crustal layers including sediments, upper, middle and lower crust deep to Moho boundary were refined in crust-scale study based on regional model in lithospheric scale. Presence of Main Zagros Fault is a bold point in our modeling which leads to better fit of gravity data.
Original Research Paper
A. Solgi; A. R. Farrokhnia; F. Zahmati
Abstract
The Haft kel anticline is one of the oil fields located in Dezful embayment of the Zagros folded zone. In this study, the most important factors influencing the fracture distribution and hydrocarbon entrapments of Asmari formation were considered, and to investigate the fractures, subsurface data and ...
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The Haft kel anticline is one of the oil fields located in Dezful embayment of the Zagros folded zone. In this study, the most important factors influencing the fracture distribution and hydrocarbon entrapments of Asmari formation were considered, and to investigate the fractures, subsurface data and analytical methods were used. These methods include inscribed circle, curvature analysis of the axial zone and changes in thickness of overburden sediments. Results of the inscribed circles and thickness maps of the overburden sediments show that the greatest concentration and development of fractures is in the hinge zone and in the eastern part of the anticline. In addition, the highest density of fractures is found to be in the outer arcs of the axial curvature sand decreases with depth. Evidences show that the most important factors controlling the fracture distribution are the geometry and the folding mechanism(flexural-slip).
Original Research Paper
Soheila Roshanzamir; K. Ahmadi
Abstract
Reservoir geophysics studies have playeda significant role in exploration and production activities during the last decades. These techniques often try to identify the lithology and fluid content of the reservoir by utilization of pre-stack seismic data. The most effective type of these studies is performed ...
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Reservoir geophysics studies have playeda significant role in exploration and production activities during the last decades. These techniques often try to identify the lithology and fluid content of the reservoir by utilization of pre-stack seismic data. The most effective type of these studies is performed in sandstone reservoirs,in which shear sonic logs increase the quality of the results. In this study, Amplitude Versus Offset (AVO) technique is applied in one of the sandstone reservoirs in the Persian Gulf. The applied methodology is based on modeling of seismic responses with different scenarios of fluid saturations in order to identify,using rock physics models, theseismic behavior of the reservoir in wells lacking shear logs. To achieve this goal, petrophysical interpretations of well data and reservoir parameters were integrated into a rock physics model, which eventually helped to recognize the seismic attributes sensitive to fluid content of the reservoir. In addition, calculation of pre-stack seismic attributes data led us to discriminate accurately the gas-oil contact. The comparison of the AVO study results with petrophysical evaluation results shows that AVO method results are very reliable and precise in the study area.
Original Research Paper
M. Samaei; A. Barzegari; M .R. Ghavimipanah; F. Ja’afari; A. Shami
Abstract
Tehran metropolitan with a high population, existence of active faults, evidence of historical earthquakes and vulnerability of its infrastructures is exposed to a high seismic risk. In the present study, considering geological reports and papers published in the past decade, three scenario earthquakes ...
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Tehran metropolitan with a high population, existence of active faults, evidence of historical earthquakes and vulnerability of its infrastructures is exposed to a high seismic risk. In the present study, considering geological reports and papers published in the past decade, three scenario earthquakes for rupture of Mosha, Niavaran and Parchin faults are presented, and synthetic accelerograms were simulated in the Tehran metropolitan. Stochastic point source method with modification of distance parameter for considering finite fault effects is adopted; and results of studies carried out by International Institute of Earthquake Engineering and Seismology (IIEES) in the recent years have been considered to account for site effects. Simulation results show considerable PGA values for Niavaran fault rupture in northern Tehran and for Parchin fault rupture in southern Tehran; also average Modified Mercali Intensity (MMI) for these scenarios are equal to IX for districts 3 and 1 in Tehran, which indicates high damage potential in those areas. Using the simulation results, we have also carried out a preliminary estimation of casualty based on the assumed scenario earthquakes. Casualty (death toll) for rupture scenarios of Mosha, Niavaran and Parchin faults are estimated to be about 5000, 117000 and 85000, respectively.
Original Research Paper
Stratigraphy and Palaeontology
A. Abdolnia; I. Maghfouri Moghaddam; D. Baghbani
Abstract
The Shahbazan Formation deposited in the Lorestan foreland basin and northeastern part of Dezful embayment zone during the Middle-Late Eocene age. In order to study the stratigraphy of the Shahbazan Formation, four surface sections of this formation in northeastern flank of Langar anticline, southeastern ...
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The Shahbazan Formation deposited in the Lorestan foreland basin and northeastern part of Dezful embayment zone during the Middle-Late Eocene age. In order to study the stratigraphy of the Shahbazan Formation, four surface sections of this formation in northeastern flank of Langar anticline, southeastern flank of Chenareh anticline, northeastern flank of Maleh Kuh anticline and southwestern flank of Poshte-Jangal anticline, have been selected. The Shahbazan Formation in Langar and Chenareh sections is composed of limestone with intercalation of dolomite. In other parts of the Lorestan such as Maleh kuh and Poshte Jangel, it consists of dolomite and intercalations of limestons. In these areas, the Shahbazan and Asmari formations form a prominent topographic unit and separating their boundary is often difficult to place, thus making it necessary to map the two formations as one unit. In this case, the two names are hyphenated as Shahbazan- Asmari Formation. According to study of benthic foraminifera in Chenareh and Langar sections, two biozone have been distinguished. The age of the Shahbazan Formation in these areas is determined as Middle- Late Eocene (Bartonian- Priabonian). In the Maleh Kuh section, the lower part of the Shahbazan- Asmari Formations is dolomitic but in the upper part it contains limestone beds with foraminifera that belong to two assemblage zones, in Aquitanian- Burdigalian age. In the Poshte Jangal section, the lower and middle parts of Shahbazan- Asmari formations are dolomitic but the upper part contains limestone beds with rare foraminifera which have been reported at the Chattian- Burdigalian beds of the Asmari Formation.
Original Research Paper
Remote Sensing
R. Ahmadi Rohany; M. H. Karimpour; B. Rahimi; A. Malakzadeh Shafaroudi; S. Najafi Afshar
Abstract
The studied area is located at the east of Bajestan city and south west of Khorasan Razavi province. This region is at the north of the Lut Block, the largest structural block in east of Iran. Structure of this area is affected by activity of deep strike-slip faults in the boundary of the blocks. Lineaments ...
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The studied area is located at the east of Bajestan city and south west of Khorasan Razavi province. This region is at the north of the Lut Block, the largest structural block in east of Iran. Structure of this area is affected by activity of deep strike-slip faults in the boundary of the blocks. Lineaments are mapped by the means of SPOT-5 and Landsat satellite data and DEM data. Structural studies were carried out in two stages: at first, main faults were indicated, mapped and analyzed and then for more detail research, total lineaments (faults and joints) were mapped and analyzed. Verification studies were conducted with field surveys. Remote sensing studies indicate importance of applying enhancement filters like standard kernels on stereoscopic data like SPOT as an efficient tool for structural studies, especially for lineament extracting. Fractal studies and using fractures statistical parameters (based on fracture map obtained by remote sensing data (in the area in addition to determining fractal dimension, were used as complementary methods for recognition structural evolution and specifying the most probability of mineralization occurrence. Fractal, structural- statistical analyzes, field and remote sensing studies on fracture systems in the area indicate that structural elements in the studied area, most probably are related to the main strike-slip faults activities and can be considered as Riedel shear fractures in its wall of damage zone. Also the results indicate that most of the lineaments in this area are extensional fractures corresponding to both dykes emplacement and alteration zones associated with mineralization. Combining the mentioned information can play important role in identifying structural evolution processes and specifying areas with more mineralization potential.
Original Research Paper
Tectonics
E. Haji; H. Safari
Abstract
The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for ...
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The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for structural measurements, during which major and minor faults and shear zones (as ductile zones) were measured and mapped. These data were then entered to GIS environment as vector layers (and attributed descriptions), resulting in preparation of a structural map. The results of field surveys along with geometric and kinematic analyses show that the major faults together with their related fault orders formed a curved shape of structures, outcropped rock unit patterns and intrusive localities. Geometric and kinematic analyses demonstrated three stages of movement: with north-south (in ductile environment), northeast-southwest (in ductile to brittle environment) and east-west (in brittle environment). These three stages caused three stages of faulting with trends along N140-150, N70-80 and N10-20 directions, which can be attributed to three orogenic phases in Precambrian and/or late Triassic (Katangai and/or Cimmerian), Cretaceous (Laramide) and Neogene (late Alpine events such as Savian to Pasadenian).
Original Research Paper
Economic Geology
A. Baharvandi; M. Lotfi; M. Ghaderi; M. R. Jafari; H. A. Tajeddin
Abstract
Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in ...
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Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in three horizons accompanied by sulfide minerals as massive and/or parallel bands within metamorphosed rhyolitic tuffs (metatuff). The deposit footwall is composed of phyllite and slate crosscut by silicic and sulfide-bearing barite veins and veinlets (stringer zone). Primary minerals in the ore are mainly barite, pyrite, marcasite, chalcopyrite and bornite and secondary minerals are chalcocite, covellite, malachite, siderite, goethite, hematite and other iron hydroxides. Gangue minerals include quartz, sericite, calcite, dolomite, feldspar and chlorite. In terms of metallic ores, the Shekarbeig deposit does not vary much having only pyrite and chalcopyrite. Types of fluid inclusions in the Shekarbeig deposit are two-phase liquid-vapour (LV), mono-phase vapour and mono-phase liquid; two-phase liquid-vapour being the dominant type in both stringer and stratiform parts. Sulfur isotope data indicate that seawater was the main mineralizing fluid for Shekarbeig mineralization. These data suggest that complete reduction of recent seawater sulfate and the rate of mixing of hydrothermal solution with cold waters in deep parts of the basin may result in precipitation of large amount of sulfides in the stringer and stratifrom zones. On the other hand, partial reduction of recent seawater sulfates provided required sulfur for the deposition of barite. Geological evidence, evaluation, lithostratigraphy, mineralization geometry and the results of fluid inclusion and sulfur isotope studies for samples from the Shekarbeig deposit indicate derivation of the hydrothermal fluids of low salinity and moderate temperature from seawater and circulation and upward movement by a heating source (probably subvolcanic intrusions) and finally cooling and deposition of the fluids as sulfate and sulfide on the sea floor due to mixing with seawater, similar to massive sulfide Kuroko-type deposits.
Original Research Paper
Geological Environment and Engineering
E. Ghadiri Soufi; S. Soltani Mohammadi; M. Yousefi; A. Aalianvari
Abstract
In mining areas, assessing toxic elements (e.g., arsenic) contamination in the soil and stream deposits is a critical issue. It is because mining activities release dangerous elements that enter the environment. In this paper, for modeling the spatial distribution of arsenic contamination in Sarduiyeh-Baft ...
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In mining areas, assessing toxic elements (e.g., arsenic) contamination in the soil and stream deposits is a critical issue. It is because mining activities release dangerous elements that enter the environment. In this paper, for modeling the spatial distribution of arsenic contamination in Sarduiyeh-Baft area, in Kerman Province, across an area of ca. 5000 km2, 1804 stream sediment samples were collected and analyzed. The recommended standard limit for arsenic in soil is 20 ppm, so samples showing arsenic concentration >20 ppm are contaminated samples, which need land reform processes. However, since the number of collected samples is limited, indicator Kriging method was used to identify the possibility of contamination. In the study area, there are 32 known occurrences of porphyry-Cu deposits. Thus, in order to estimate the arsenic contamination in the unsampled locations, indicator kriging method was used. The results indicate arsenic contaminations in north and northwest parts of the study area, which could be occurred by mining of the porphyry-Cu deposits. However, the results show that there is no arsenic contamination in the eastern part although there are several mining sites with high activities.
Original Research Paper
Exploration and Mining
A. Uromeihy; E. Sadat Razavi; V. Baghri
Abstract
Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active ...
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Rasht City is capital of Gilan Provence and is considered as one of the metropolitans along the south coast of the Caspian Sea. In terms of geological setting, the city is situated to the north of the Alborz Mountains and in the Gorgan-Rasht sedimentary zone. The area is characterized by many active faults, with the Khazar fault being regarded as the most effect one, which can produce a gravity acceleration of 0.3g for a major earthquake. According to geotechnical data from exploration boreholes, the ground surface along Line 2 of Metro in the city comprises mainly a sequence of silts and clays with interlayers of gravel and sand. Due to high level of groundwater table, abundance of fine-grained soils, high seismicity potential, and production of ground vibration during movement of the train, liquefaction can be expected to occur along the Metro line. The aim of this paper is therefore to evaluate the liquefaction hazard potential along the Line 2 of Metro of the Rasht City by preparing a hazard zonation map. Liquefaction hazard zonation mapping was carried out using data gathered from 14 exploration boreholes drilled to a depth down to 40 meters integrated into Analytical Hierarchy Process (AHP) in the GIS modelling system. In this regards, five layers of information including soil type, SPT number, overburden pressure, plastic index and maximum gravity acceleration were considered. The results indicate that the range of liquefaction hazard varies between low to very high, and the maximum rate of liquefaction is expected in BC2 and I2 stations (Sazeman-e-Ab and Husain Abad areas, respectively). Soil type and groundwater table are recognized to be the most effecttive agents in inducing potential liquefaction.
Original Research Paper
R. Pourimani; M. Zahedi; M. Mirzaei
Abstract
In this research magmas (igneous rocks) of 300 hectares area covering of hot springs of Mahallat zone of Iran were studied. Twenty samples of outcrops of magmas were collected. In order to obtain homogeneous fine powder, part of all samples were crushed by jaw and ball milling and dried and passed through ...
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In this research magmas (igneous rocks) of 300 hectares area covering of hot springs of Mahallat zone of Iran were studied. Twenty samples of outcrops of magmas were collected. In order to obtain homogeneous fine powder, part of all samples were crushed by jaw and ball milling and dried and passed through mesh number 40 and packed in Negin containers and sealed. Thin cross section were prepared for all samples and mineral components were determined in mineralogy laboratory. Specific activities of 226Ra, 232Th and 40K of all samples were determined using gamma ray spectrometry method employing high purity germanium (HPGe) detector with its electronic system. Specific activities of these radionuclides in samples obtained from 22.15 ± 1.34 to 62.68 ± 3.76, from 10.69 ± 1.43 to 40.55 ± 2.15 and from 59.99 ± 5.07 to 1467.30 ± 17.48 in Bq/kg respectively. Heat rate generation due to radioactivity decay for samples calculated that varied from 0.69 to 1.82 in µW/m3. The mean Heat production of magma with ten cubic kilometer volume obtained as 13.60 kW and the energy for increasing of water temperature with yields of 35.5 l/s from 15º C to 100º C is necessary 12.7 kW. Therefore consideration level of radioactivity and long life of magma of this region and expansion in conic form under hot springs seem to be the resource of heat due to radioactivity decay of 235U, 238U and 232Th series and 40K.
Original Research Paper
Economic Geology
M. Movahednia; E. Rastad; A. Rajabi; F. Choulet
Abstract
The Ab-Bagh Zn-Pb deposit is located in the central part of the Sanandaj-Sirjan zone (SSZ) and at the southeastern part of the Malayer-Esfahan metallogenic belt. This deposit is hosted by Upper Jurassic-Lower Cretaceous sedimentary sequence. Zinc and lead mineralization occurred within two horizons. ...
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The Ab-Bagh Zn-Pb deposit is located in the central part of the Sanandaj-Sirjan zone (SSZ) and at the southeastern part of the Malayer-Esfahan metallogenic belt. This deposit is hosted by Upper Jurassic-Lower Cretaceous sedimentary sequence. Zinc and lead mineralization occurred within two horizons. The ore horizon 1 is hosted by Late Jurassic-Early Cretaceous black shale and siltstone. The ore body displays a wedge-like shape and is located close to syn-sedimentary fault. The ore horizon 2 occurs in lower Cretaceous carbonates and includes a massive ore facies that is concordant with host rock layering. It is also underlain by a stockwork facies. Weathering processes led to a supergene ore stage at Ab-Bagh deposit in parts toward the surface. Based on geology, mineralogy and geochemistry, two types of non-sulfide ore were distinguished: the white ore and the red ore. The white ore is a wall-rock replacement mineralization that contains high Zn, low Fe and a very low concentration of Pb. To the opposite, the red ore formed after the direct replacement of sulfide protore and it typically contains low Zn, high Fe and medium Pb± As concentrations. Supergene ore consists of smithsonite and hydrozincite. Minor cerussite, Zn-rich clays, greenockite, covellite and Fe-Mn oxides were also identified. The supergene part of the Ab-Bagh deposit formed as a consequence of long time weathering of a SEDEX-type sulfide protore. Oxidation of sulfide minerals (mainly pyrite and sphalerite), carbonate buffering reactions and precipitation of secondary Zn-bearing minerals are the main geochemical process involved. The REE patterns of the white non-sulfide ore are similar to that recorded in the host rocks but REE patterns of red ore, is similar to sulfide ore. The comparison with other major non-sulfide Iranian deposits suggests that Ab-Bagh deposit is very similar to Kolahdarvazeh and Mehdiabad deposits; it also shows lots of similarities with other worldwide examples (e.g. Moroccan non-sulfide ore deposits).
Original Research Paper
Sedimentology
S. A. Moallemi; M. A. Salehi; A. Zohdi
Abstract
In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison ...
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In this study, the sandstones of the Razak Formation at the Finu and Hanudun outcrops and at Sarkhun Field north of Bandar-Abbas have been investigated by petrography and geochemistry analyses to discriminate provenance for determination of tectonic setting, parent rock and palaeoweathering and for comparison with the Ahwaz Sandstone of Asmari Formation. The Razak Formation mainly consists of marl, sandstone, conglomerate and sandy limestone. The results of geochemical investigation of major and trace elements indicated that the sedimentation of the Razak Formation took place in an active continental margin. Provenance analysis shows that the siliciclastic sediments of the Razak Formation were largely derived from mafic and intermediate igneous, low- to high-grade metamorphic and sedimentary rocks. Chemical weathering indices suggested that their source area underwent a moderate degree of chemical weathering in an arid climate. It seems that the sediments of the Razak Formation are results of erosion from a mixture of ophiolitic-igneous rocks belonging to the Neo-Tethys oceanic crust, metamorphic rocks and other sedimentary strata deposited in Zagros sedimentary basin during foreland basin evolution. Wedge thickness of the Razak Formation changes from the hinterland thrust basin towards the Zagros trough and ridge basin and finally disappears in the coastal Fars region. The presence of polymictic conglomerate and coarse-grained sandstone with abundant rock fragments could be considered as additional evidence for the source of Razak Formation from the Zagros imbricated zone.
Original Research Paper
Stratigraphy and Palaeontology
S. Senemari
Abstract
Calcareous Nannofossils of the Gurpi Formation have been investigated at Kalchenar section (Northwest of Izeh). In this section, the Gurpi Formation is mainly consists of marls, shaly marls and marly limestones. For introducing index species, calcareous nannofossil assemblages and biozones, 150 slides ...
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Calcareous Nannofossils of the Gurpi Formation have been investigated at Kalchenar section (Northwest of Izeh). In this section, the Gurpi Formation is mainly consists of marls, shaly marls and marly limestones. For introducing index species, calcareous nannofossil assemblages and biozones, 150 slides have been studied which led to the recognition of twelve biozones. As a result, 61 species, 35 genera of calcareous nannofossils were detected. According to the identified biozones, the age of the Gurpi Formation is Late Campanian to Late Paleocene (Late Selandian) and K/Pg boundary is continuous at the studied interval, that is corresponding to CC21- CC26of zonation scheme of Sissingh (1977) and NP1- NP6 of zonation of Martini (1971).
Original Research Paper
Petrology
Z. Gharamohammadi; A. Kananian; M. Eliassi
Abstract
The Dehe Bala pluton is exposed approximately 45 km south-west of Boein Zahra town, Qazvin province. This pluton includes several mafic microgranular enclaves (MMES) with ellipsoidal and rounded shapes and varying sizes (from a few centimeters up to 30 cm). The MMEs are composed of diorite, monzodiorite ...
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The Dehe Bala pluton is exposed approximately 45 km south-west of Boein Zahra town, Qazvin province. This pluton includes several mafic microgranular enclaves (MMES) with ellipsoidal and rounded shapes and varying sizes (from a few centimeters up to 30 cm). The MMEs are composed of diorite, monzodiorite and diorite-gabbro while the host rocks comprise mainly granodiorite. The presence of disequilibrium textures in enclaves, such as plagioclase phenocrysts with repeated resorption surfaces and sieve texture, quartz ocelli and acicular apatite, suggest a varity of magma mixing processes affecting the Dehe Bala pluton. The distribution of major, trace and rare earth elements apparently reflect exchange between the MMEs and the felsic host rocks. Unusual REE enrichment of the enclaves compared to the country rocks can be attributed to significant differences in their parent magma compositions. The complexity of the morphology of the enclaves (fractal dimension) caused by magma mixing processes. Fractal dimensions of the enclaves vary between 1.14 to 1.29. The frequencies of Dbox = 1.29 is the highest frequency in histogram. According to the fractal dimensions of enclaves, the logarithm of the viscosity ratio between the host granodiorite and the enclave ranges between 0.56 to0.96 with most values clustering around 0.96. The most of enclaves in the Dehe Bala pluton characterized by silica content around 56 w% and a high fractal dimension. These evidence confirmed the occurrence of slight hybridization between the mafic enclave magma and surrounding felsic magma, causing increasing of viscosity difference between the host granodiorite and the enclave magmas.
Original Research Paper
S. Esmailnezhad; N. Taghipour; A. A. Hassannezhad
Abstract
The Nukeh iron deposit is situated at the north of Semnan and at south of Central Alborz structural zone. Volcano-pyroclastic rocks with Eocene age are the host of this deposit. Iron mineralization occurs as massive, disseminated, vein and breccia types in the Nukeh deposit and magnetite, hematite, pyrite, ...
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The Nukeh iron deposit is situated at the north of Semnan and at south of Central Alborz structural zone. Volcano-pyroclastic rocks with Eocene age are the host of this deposit. Iron mineralization occurs as massive, disseminated, vein and breccia types in the Nukeh deposit and magnetite, hematite, pyrite, chalcopyrite, garnet, epidote, quartz and calcite are the main minerals in this deposit. Fluid inclusions and stable isotopes (O, C, S) have been used to reveal the physico-chemical characteristics of hydrothermal fluids and genesis of the Nukeh Fe deposit. Seven types of fluid inclusions are identified in quartz, according to the phase numbers, which include, liquid inclusions (L), liquid-rich inclusions (L+V), vapor-rich inclusions (V+L), vapor inclusions (V), simple brine inclusions (L+V+S), halite-bearing liquid inclusions (L+S) and opaque-bearing liquid-rich inclusions (L+V+O). The ranges of homogenization temperature and salinity of liquid-rich fluid inclusions in quartz are 100-200˚C and 10-20 wt. % NaCl equivalent, respectively, whereas the ranges of homogenization temperature and salinity of vapor-rich fluid inclusions are 350-500˚C and 10-30 wt. % NaCl equivalent, respectively. Also homogenization temperature and salinities of liquid-rich fluid inclusions in calcite in garnet (type a) and magnetite (type b) zones is 75-125 ˚C but the salinity of fluid inclusions in calcite in garnet zone (15-25 wt. % NaCl) is more than salinity of these inclusions in magnetite zone (10-20 wt. % NaCl). δ13C and δ18O values of calcite (n=15) vary between -1.9 to +0.1 ‰ (VPDB) and -19.4 to -14.9‰ (SMOW), respectively. The average value of δ18OWater is of +17.85‰ (SMOW) in the Nukeh Fe deposit is different from the values for the primary magmatic fluid. Pyrite is the main sulfide mineral in the Nukeh Fe deposit and δ34S values of pyrite (n=9) is within the range of +3.9 to +5.4 ‰ CDT . The source of sulfur is considered to be magmatic on this basis. Fluid inclusions and stable isotopic (O, C, S) data suggest that the ore-forming fluids evolved by the various mixtures of magmatic brines and meteoric water and probably the genesis of the Nukeh Fe deposit is similar to skarn deposits.
