Editor-in-Chief Lecture
S. M. Masoudi; F. Fereidoni; & A. A. Matkan
Abstract
In this study, for the first time, Pumices around Damavand Mountain is studied by IRS-1C, Aster and ETM+ images. For this purpose at first, all images are preprocessed. It means geometric corrections and registering images together and with topography maps (1:25000) are done. Then atmospheric corrections, ...
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In this study, for the first time, Pumices around Damavand Mountain is studied by IRS-1C, Aster and ETM+ images. For this purpose at first, all images are preprocessed. It means geometric corrections and registering images together and with topography maps (1:25000) are done. Then atmospheric corrections, calibration of radiance and reflectance and topographic correction with Minneart method are done too. Preprocessing, some techniques like PCA, IHS, OIF, FCC and SAM have been done. Pan image of IRS-1C satellite for data fusion in visible and near infrared of Aster at visual interpretation and recognizing of roads and mines is better than ETM images. After data preprocessing, some techniques like PCA, IHS, OIF, FCC and SAM have been done. Pan image of IRS-1C satellite for data fusion in visible and near infrared of Aster at visual interpretation and recognizing of roads and mines is better than ETM images. IHS and PCA methods equally have separated clearly Pumice mines and trachyandesites without vegetations and soils covers. With respect to VNIR of Aster has more intensity than other spectral areas. Also because of high topographic changes and pampas vegetation, visible bands and Very Near Infrared (VNIR) of Aster aren't too useful. These spectral areas are caused mixing classes together, especially limestones and pumice. Totally for most of stones and different ores, spectral area of Short Wave Infrared (SWIR) of Aster has the best ability. For categorizing and extracting pumices potential layers from images, sampling is done on pixel or pixels that contain pumice mines. Because of less expansion of mines, samples are picked up on just one pixel or in maximum case ten pixels. According to that limitation, Spectral Angle Method (SAM) technique has more ability than the other methods. Use of DEM for separation flat or low dip lands whereas are placed for Pumices in northern, eastern and some southern parts of studied area is effective, but any worthwhile tracks of pumice weren’t found in south-west of mountain. Finally mining hopeful areas in cast of mining potential map is prepared. By calculating the overlay of effective geology structure layer with pumice mines areas layer, which is extracted from PAN image, the amount of overlay is calculated ninety three percent.
Original Research Paper
R. Deevsalar; M.V. Valizadeh
Abstract
The results of field studies (i.e. shape, dimensions, spatial distribution, condition of enclaves and xenoliths in the host rocks at available outcrops) experimental observations (i.e. petrographical and microstructural study of enclaves and xenoliths and whole rock geochemistry of magmatic encalves) ...
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The results of field studies (i.e. shape, dimensions, spatial distribution, condition of enclaves and xenoliths in the host rocks at available outcrops) experimental observations (i.e. petrographical and microstructural study of enclaves and xenoliths and whole rock geochemistry of magmatic encalves) show that magmatic enclaves are mafic and felsic types, while xenoliths are hornfelsic. Elongation of magmatic enclaves and hornfelsic xenoliths along their apparent longitude axis in the margin of intrusive body are attributed to influence of stress on enclaves in melt or semi-solid phases and xenoliths in plastic form. In addition, this is related to impact of high force of magmatic flow in contact with metamorphic wall rocks. This indicates that the origin of xenoliths is the metamorphic rocks which lie at the periphery of the intrusive body. Existing of aligned mafic enclaves in the host, in addition to, presence of signs of plastic deformations (in microscopic scale) in micro-scale fluid features can be attributed to superimposition of solid-state deformation on magmatic flow. Due to lack of solid-state plastic deformation evidences, applicability of magmatic flow criteria and distinguishable interface of magmatic enclaves with host rocks in microscopic and macroscopic scales, spherical, globular, ellipsoidal and spindle shapes of mafic magmatic enclaves attributed to presence of theirs as mafic globule and packets in the host felsic magma, and also their similarity in superficial appearance, textural, mineralogy and geochemistry with the host rock, attributed to their different origin and magma mixing event. The formation of irregular shaped magmatic felsic enclaves with recognizable mineralogical and geochemical similarity to the host rocks, which are observed at the periphery or ceiling of the plutons, related to peripheral interruption in the primary phase of magmatic injection caused by the high pressure of consecutive injection pulse and replacement of new magmatic charge.
Original Research Paper
M. Forouzanfar; H. Abrishami-Moghaddam; M. Dehghani
Abstract
Despite the wide application of SAR images in lineaments extraction, DEM generation and displacements determination, their radiometric quality and interpretability is degraded due to the presence of a multiplicative noise called speckle. Therefore, the enhancement of SAR images is an important step before ...
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Despite the wide application of SAR images in lineaments extraction, DEM generation and displacements determination, their radiometric quality and interpretability is degraded due to the presence of a multiplicative noise called speckle. Therefore, the enhancement of SAR images is an important step before using them in any application. In this paper, a new image enhancement method tailored to SAR images is proposed. In this method, the logarithmically transformed SAR image is decomposed using the dual-tree complex wavelet transform (DTCWT).In order to effectively extract the wavelet interscale dependencies, the signal component of wavelet coefficients is modeled with an isotropic stable distribution, while the noise component is approximated using an isotropic Gaussian model. A bivariate Bayesian estimator is then designed to effectively remove speckle from noisy coefficients in the complex wavelet domain. Both quantitative and qualitative comparisons of the proposed method with new speckle reduction methods, demonstrate its higher performance in speckle reduction from SAR images
Original Research Paper
Z.K. Mossadegh; M.H. Adabi; A. Sadeghi
Abstract
We studied the geochemistry of the Asmari Formation in two outcrop sections: Tang-e-Sapou a 260 m section near Dehdasht City (Kohgiluyeh va Bouyer Ahmad Province) and Tang-e-Ban a 214 m section near Behbahan City (Khozestan Province). Sampling included the complete Asmari Formation and the top of the ...
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We studied the geochemistry of the Asmari Formation in two outcrop sections: Tang-e-Sapou a 260 m section near Dehdasht City (Kohgiluyeh va Bouyer Ahmad Province) and Tang-e-Ban a 214 m section near Behbahan City (Khozestan Province). Sampling included the complete Asmari Formation and the top of the Pabdeh Formation. The Late Oligocene to Early Miocene Asmari Formation lies above the Pabdeh Formation and is overlain by the Gachsaran Formation. Elemental geochemistry (Fe, Mg, Na, Sr, Mn, Ca), and Oxygen and Carbon isotope analyses indicate that meteoric diagenesis affected carbonates of the Asmari Formation. The δ18O/δ13C data plots in an inverted J-trend suggesting that meteoric diagensis occurred in a closed to semi-closed system. The geochemistry also suggests that the original mineralogy was Aragonite. The boundary between the Pabdeh and Asmari Formations can be recognized by changes in the δ 18O and δ 13C. In the Pabdeh Formation the δ 18O and δ 13C values are mostly negative, but in the Asmari Formation values range from positive to negative. Strontium is much higher in the Pabdeh Formation than in the Asmari Formation. Changes in isotope and elemental geochemistry clearly show the Chattian-Aquitanian and Aquitanian-Burgidalian boundaries.
Original Research Paper
M. A. Salehi; M. H. Adabi; H. Ghalavand; M. Khatibi-Mehr
Abstract
The Fahliyan Formation with the age of Lower Cretaceous (Berriasian-Hauterivian) were studied for microfacies analysis, diagenesis and original carbonate mineralogy in the type section at Fahliyan Anticline and subsurface section in well number 55 of Gachsaran Oil Field. Petrographic studies led to the ...
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The Fahliyan Formation with the age of Lower Cretaceous (Berriasian-Hauterivian) were studied for microfacies analysis, diagenesis and original carbonate mineralogy in the type section at Fahliyan Anticline and subsurface section in well number 55 of Gachsaran Oil Field. Petrographic studies led to the recognition of 10 microfacies that were deposited in four facies belts: tidal flat, lagoon, shoal and open marine. The observed facies patterns indicated a carbonate rimmed-shelf depositional environment. Recognition of different type of cements shows that the Fahliyan Formation has mostly undergone meteroric diagenesis. Major and minor elements and carbon and oxygen isotope values indicate that aragonite was the original carbonate mineralogy in the Fahliyan Formation, and suggests that alteration occurred in a closed diagenetic system, with low water/rock interaction.
Original Research Paper
J. Daneshian; M. Shahrabi; M. Akhlaghi
Abstract
75 samples of the Qom Formation in Andabad, northeast Mahneshan, were investigated. The Qom Formation in the examined section with a thickness of 301m, mainly consists of limestone and marl, and disconformably overlies the Lower Red Formation and lies under the sediments of the Upper Red Formation. A ...
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75 samples of the Qom Formation in Andabad, northeast Mahneshan, were investigated. The Qom Formation in the examined section with a thickness of 301m, mainly consists of limestone and marl, and disconformably overlies the Lower Red Formation and lies under the sediments of the Upper Red Formation. A study of foraminifera was led to identifying 42 genera and 70 species of the benthonic and plankthonic foraminifera, which 37 genera and 57 species is reported from this area for the first time. Among them, benthonic foraminifera have more varieties and abundances, and used for biostratigraghy. Based on the identified foraminifera, the Andabad section is comparable to Assemblages Zone 1 and 2 introduced by Adams and Bourgeois. On the basis of occurrence of the index foraminiferal species and their stratigraphic distribution, the age of the Qom Formation in the studied section is Early Miocene (Late Aquitanian to Burdigalian).The assemblage, abundance, and species diversity of foraminifera in the examined samples shows noticeable changes in the paleoenvironmental conditions. The maximum diversity of foraminifera is sixteen species. Based on species diversity, the strata classified to nine assemblages A to I. The abundance of foraminifera in each assemblage indicates that the sediments of the Qom Formation belong to inner shelf environments.
Original Research Paper
samad alipour; R. Nikrouz
Abstract
Shahrestan mining district is the largest extensive granitic stone province in Iran. There are 25 active mines in this area. The study of rose diagrams with statistical joint systems at this ornamental stone mining district carried out in order to reduce expenses with low waste disposal of mining extraction. ...
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Shahrestan mining district is the largest extensive granitic stone province in Iran. There are 25 active mines in this area. The study of rose diagrams with statistical joint systems at this ornamental stone mining district carried out in order to reduce expenses with low waste disposal of mining extraction. The most types of intrusive rocks are syenite, monzonite, gabbro and granite cropped out in the region. Alkali syenite is the main rock type in spite of varying color and texture. Diversity of apparent color and rock composition associated with variety of color in low distances, existence of joints, faults and thrusts around formations and rocks of moderately being metamorphosed, are the source of major problems in the region from the exploration till the excavation stages. The study results indicate that the main folding trend is extended in a northwest-southeast direction. Therefore the direction of quarries in central part must be developed in a north-south direction and in the northwest part in northwest–southeast direction while in the east of Shahrestan quarries must be created in a northeast – southwest trend.
Original Research Paper
H. Amini; M. Fattahi; M. R. Ghassemi
Abstract
Doruneh is an active left- lateral strike- slip fault in North-East Iran. Surface trace of this fault is about 700 km long, and cuts across Quaternary and Tertiary deposits. In some places along the fault, sediments of Paleogene. Neogene, and alluvial fans of Quaternary age are displaced ...
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Doruneh is an active left- lateral strike- slip fault in North-East Iran. Surface trace of this fault is about 700 km long, and cuts across Quaternary and Tertiary deposits. In some places along the fault, sediments of Paleogene. Neogene, and alluvial fans of Quaternary age are displaced by the fault. Left- lateral displacement between 91-457 m are evident in Landsat images between east of Beiragh and east of Khalil-abad. Displacements are also evident in streams that are incised over the above mentioned deposits. We have tried to estimate the recent history of activity on the fault on the basis of the measured displacements and estimated slip rates of the fault. Estimated age of left- lateral movement inception on the fault is very much younger than the displaced geologic units. These observations indicate that Doruneh Fault has been mostly active during the last few millions, which in turn proves the fault to be an active structure.
Original Research Paper
M. Hosseini-Barzi; N. Etemad Saeed
Abstract
The Early Cambrian Lalun Formation in Poshte- Badam block has been studied in Bahmoo section with 550 m thickness, to illuminate its sedimentary environment and sea level changes. The field investigations, collection of 110 paleocurrent data, petrography, study of SEM images and XRD analysis of shale ...
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The Early Cambrian Lalun Formation in Poshte- Badam block has been studied in Bahmoo section with 550 m thickness, to illuminate its sedimentary environment and sea level changes. The field investigations, collection of 110 paleocurrent data, petrography, study of SEM images and XRD analysis of shale samples have been used for facies analysis, paleocurrent recognition and sedimentary environment reconstruction. The facies analyses imply 5 silisiclastic coarse grained (Gm), medium grained (Sp, St, Sh) and fine grained (Fl) lithofacies and 1 carbonate (dolomite) microfacies. The lithofacies, bipolar bimodal paleocurrent pattern and petrographic evidences such as the existence of glauconitic sandstones with high textural and compositional maturity imply deposition of these sediments in a Tidal Flat environment. Studying the relative sea level changes of Lalun deposits in this area imply two sequences which have been bounded between SB1 unconformities.
Original Research Paper
Y. Sharghi; F. Alinia; H. R. Siahkoohi
Abstract
Seismic travel time tomography uses seismic waves to image velocity distribution inside the ground. This method has been widely applied to practical applications in many fields including earth sciences. In this method, first-arrival times of seismic waves due to artificial sources, observed at receivers ...
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Seismic travel time tomography uses seismic waves to image velocity distribution inside the ground. This method has been widely applied to practical applications in many fields including earth sciences. In this method, first-arrival times of seismic waves due to artificial sources, observed at receivers in the vicinity of the exploration target are analyzed to obtain the velocity distribution within the propagation area. This paper describes the seismic tomography investigation performed at the abutments of Bakhtyari Dam site. The study aimed to find the low-velocity zones that may correspond to jointed media where seepage most likely happens. We performed 3-D tomographic inversion on Bakhtiari dam seismic data. To perform ray tracing and travel-time computation at each iteration, we used Um and Thurber (1987) method and for inversion step we used SIRT method. In most of the tomograms, average velocity was 3km/s. According to the Barton relation (2006) the seepage potential in dam sit abutments, is low. A low velocity zone has been detected above the 690 m level in right abutment. It shows that the weak zones extended from surface down to this level. Despite the presence of some weak zones, the rock mass quality is good, and the design of the grout curtain could help to bypass the reservoir water away from these seepage paths
Original Research Paper
H. Mosadegh; M. Lankarani
Abstract
The carbonate facies of Permian in Gaduk area (Central Alborz) are dominated by calcareous algae. Study of the facies resulted in recognition of several species of Cyanobacteria, Dasycladacean and Gymnocodiacean green algae and also Phylloid algae. In the studied succession, Phylloid algae are identified ...
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The carbonate facies of Permian in Gaduk area (Central Alborz) are dominated by calcareous algae. Study of the facies resulted in recognition of several species of Cyanobacteria, Dasycladacean and Gymnocodiacean green algae and also Phylloid algae. In the studied succession, Phylloid algae are identified in carbonate shoal facies. Cyanobacteria mostly occurred in tidal to lagoonal facies, as encrusters. Dasycladacean and Gymnocodiacean green algae mostly occurred in inner ramp facies. Gymnocodiaceans were found in deeper parts in comparison to Dasycladaceans. Occurrence of Cyanobacteria in depositional sequences coincides with type-one sequence boundaries. Phylloid algae are identified in the facies related to transgressive surfaces and maximum abundance of Dasycladaceans and Gymnocodiaceans was found around maximum flooding surfaces and in highstand systems tracts. Abundance of the calcareous algae shows an increasing trend from the base to the top of carbonate parasequences. Proliferation of the calcareous algae was found in close relationship to climate warming and ice-house to green-house transition in Permian of Alborz.
Original Research Paper
zahra badrzadeh; M. Sabzehei; E. Rastad; M. H. Emami; D. Gimeno
Abstract
The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons ...
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The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons in distal part of the deposit, the occurrence of a stringer zone discordantly under massive ore, the presence of pyrite as the main sulfide mineral, brecciated textures and mineralogical zonation in the massive ore, all suggest that the Sargaz deposit can be classified as a volanogenic massive sulfide deposit. The mineralogy is reasonably simple, with pyrite being the main sulfide mineral, with lesser chalcopyrite and sphalerite. On the basis of different generation of minerals, shape, size, their mutual geometry, relative timing of crosscutting structures and replacement features, brecciated textures and mineralogical zonation indicate that the growth history of the Sargaz deposit was complex due to syn and post depositional processes. Based on mineralogical, textural and paragenetic relationships, four principal stages of mineralization are recognized. Stage I mainly consist of fine grained pyrite (As rich), and locally sphalerite, quartz and barite. Framboidal pyrite, colloform pyrite and sphalerite were formed during this stage. After stage 1 mineralization, collapse of the sulfide mounds took place probably due to dissolution of anhydrite matrix, producing accumulations of pyrite breccias. Following this mound collapse, during stage II, pyrite (Co rich), sphalerite, tetrahedrite-tenantite and galena were formed as euhedral and coarse grains. Stage III deposits consist of chalcopyrite replacements and zone refining process. During this stage, due to zone refining, a chalcopyrite-pyrite zone was developed at the lower part of the massive sulfide lens and a sphalerite-rich zone formed in the upper part. During stage IV, over refining process, led to the dissolution of stage III chalcopyrite and base-metal depleted pyrite body in the lowermost part of the massive sulfide lens and carbonate veins were emplaced into the sulfide lens replacing earlier barite.
Original Research Paper
Hamid Nazari; J-F Ritz; R Walker; R Salamati; A Ghasemi; A Shafei
Abstract
The Firouzkuh Fault in most of its extension is located at the southern side of Firouzkuh Valley in west of the Central Alborz. It is a SW – NE prominent structure with a 70 km long on a sinistral –normal fault. It has been known as a south-dipping reverse fault.Paleoseismic analysis ...
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The Firouzkuh Fault in most of its extension is located at the southern side of Firouzkuh Valley in west of the Central Alborz. It is a SW – NE prominent structure with a 70 km long on a sinistral –normal fault. It has been known as a south-dipping reverse fault.Paleoseismic analysis and C14 dating along the Firouzkuh left -lateral strike-slip fault indicate that Central Alborz has been shaken by large earthquakes during the Holocene. Here we present the data carried out of one of the two excavated trenches with 15 m long, 2m wide, ~ 4m deep in the east of Firouzkuh, where we found some evidence for last paleoearthquake associated to seismic re-activity on Firouzkuh Fault in the second trench (F2) that dug across a gauge zone. The last event is evidenced by cutting young superficial deposit where this faulted unit stratigrafically covered alluvium deposits yielded dated human bones fragments. The bones found in 60-70cm-deep of trench which a C14 age of 1159 ± 28 BP. Regarding to estimated slips per event on paleoseismological log of eastern wall of trench F1, event magnitudes for each paleoearthquakes are M≈7.
Original Research Paper
M. Rezaei; A. Sargezi
Abstract
Over-exploitation from Goharkuh plain aquifer, southwest of Zahedan, resulted in water table drawdown. In order to assessing the effect of artificial recharge, numerical model of groundwater flow of the aquifer was developed. Well loges, hydrogeologic parameters, pizometric heads and results of pumping ...
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Over-exploitation from Goharkuh plain aquifer, southwest of Zahedan, resulted in water table drawdown. In order to assessing the effect of artificial recharge, numerical model of groundwater flow of the aquifer was developed. Well loges, hydrogeologic parameters, pizometric heads and results of pumping tests were used in this study. The flow model is well calibrated and used to simulate future water level fluctuations. Steady state condition has been considered in January of 2003 because of low fluctuation in groundwater level in this period. The Sensivity analysis related to a few parameters and verification for period of February of 2004 to February of 2005 has performed. The results indicate that groundwater level is reducing in Goharkuh plain aquifer. Maximum drawdown occurs in the east part of the aquifer. Aquifer reaction has been assessed by definition of different scenarios to identify the best location for artificial recharge. Based on the result, the north part of the aquifer (close to pizometer P9) is the best location for performing artificial recharge.
Original Research Paper
M. H. Basiri; S. Seyed Salmasi
Abstract
The precious stones are one of the vast and high profit potential of national income for many countries. Nowadays exploration, processing and exports of gemstones play important role in the economy of the many countries such as South Africa, Burme, Thailand, China, India, the United States and so on. ...
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The precious stones are one of the vast and high profit potential of national income for many countries. Nowadays exploration, processing and exports of gemstones play important role in the economy of the many countries such as South Africa, Burme, Thailand, China, India, the United States and so on. So omitting this industry from these countries is equivalent with excluding oil industry in our country. Unfortunately in spite of having high quality of some gemstones such as Turquoise and Demantoid Garnet in Iran, the substantial amount of jewels are imported illegally. This is a central threat for enhancement of this industry. Having several thousand years heritage of art and Islamic culture are the important facts for developing this industry in Iran. In this paper the precious stones industry is analyzed. Finally by implementing the SWOT method the main strategies needed to renovate and ameliorate this industry in the country are presented.
Original Research Paper
Monireh Kheirkhah; M. H. Emami
Abstract
At the farthest end of NW Iran, the Quaternary basalts crop out in Azerbaijan province, located in Alpine – Himalaya belt and highly pleatue of Iran-Turkish, eastern Anatolian. The Quaternary volcanic units of NW Azerbaijan cover a broad compositional range from basalts, basaltic andesite, trachy ...
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At the farthest end of NW Iran, the Quaternary basalts crop out in Azerbaijan province, located in Alpine – Himalaya belt and highly pleatue of Iran-Turkish, eastern Anatolian. The Quaternary volcanic units of NW Azerbaijan cover a broad compositional range from basalts, basaltic andesite, trachy andesite to trachyte. These rocks are erupted from deep tension, strike-slip faults in a pull a part basin and volcanic centers. Source of primary magmas and crustal contamination processes have certainly contributed to the understanding of the origin of basaltic rocks. Based on field area, petrography and petrology studies, 10 samples were selected for 143Nd/144Nd and 87Sr/86Sr measurements. The obtained results were correlated with other isotopic data of similar Quaternary basaltic rocks from Turkey. Isotopic study indicates that all of these rocks are derived from mantle and plot in Bulk Earth field and mantle array. The basaltic rocks in the northern area are derived from a depleted mantle and those from the southern area shows contamination by crust.
Original Research Paper
N. Khanmohammadi; A. Khakzad; J. Izadyar
Abstract
Zaker iron deposit is located in the northeast of Zanjan city and is a part of Tarom volcano – plutonic belt in Azarbaijan – West alborze structural zone. The main rocks of the area consist of folded volcanic - volcanoclastic rocks including breccia tuff, lapilli-tuff and andezitic – ...
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Zaker iron deposit is located in the northeast of Zanjan city and is a part of Tarom volcano – plutonic belt in Azarbaijan – West alborze structural zone. The main rocks of the area consist of folded volcanic - volcanoclastic rocks including breccia tuff, lapilli-tuff and andezitic – basaltic lava of Amand member of Karaj formation with Eocene age that folded. Plutonic rocks with probably Oligocene age with various lithology changing from quartzmonzodiorite, quartzmonzonite to quartzsyenite with NW-SE trend were intruded into the volcanic – volcanoclastic rocks. Fe-mineralization occurred in interval of plutons and volcanic - volcanoclastic rocks. The main ore mineral is magnetite – apatite with minor amounts of quartz and calcite. As well as magnetite- apatite mineralization, pyrite with minor amounts of chalcopyrite occurred in sulphide veinlets. The mineralization has been seen in five forms: veinlets of magnetite in form of stock- work, massive magnetite- apatite, banded magnetite- apatite, coarse grained magnetite- apatite veins and sulphide veinlets. Intrusion of ore deposit into host volcanic rocks, are associated with skarn metasomatism that form actinolite, talc, chlorite, phlogopite, quartze, calcite and epidote. Geothermobarometry for the skarn part, indicate that XCO2 is about 0.9, pressure of 2 kbar and the temperature is about 400-500 0C for metamorphic reactions. Detailed studies on textures and structures suggest the source of the iron from Zaker granitoid body and volcanic rocks are host rocks for iron deposit. Mineralography investigations are indicative of magmatic origin and show the best correlation with "Kiruna–type" iron ores.
Original Research Paper
A. Rajabi-Harsini
Abstract
Silurian shales (Sarchahan Formation), with high volume of organic matter, are the major source rock of Dehram Group reservoir in South Pars Gas Field. Residual oil (bitumen) were seen on some parts of Kangan Formation core. According to some reports, Lower Triassic (Kangan Formation) sediments is a ...
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Silurian shales (Sarchahan Formation), with high volume of organic matter, are the major source rock of Dehram Group reservoir in South Pars Gas Field. Residual oil (bitumen) were seen on some parts of Kangan Formation core. According to some reports, Lower Triassic (Kangan Formation) sediments is a possible source rock, for Kangan reservoir contents (gas and condensate). Recent geochemical study on tar and asphaltic oil of Kangan Formation (not reservoir contents), shows that these oily materials were produced from shaly and shaly- limestone layers of Kangan Formation, but due to low TOC content , poor source rock potential, and low maturity level (late diagenesis) of Kangan, this Formation is incapable of production of huge amount of gas and condensate. It seems that the produced hydrocarbons from shaly and limestone layers of Kangan Formatin, has no relation with hydrocarbons generated from Silurian shales.
Original Research Paper
A. A. Baharifar
Abstract
Chloritoid as one of the common metamorphic mineral in low to medium grade metapelites, is absent in metapelitic rocks of Hamedan area. Comparing with geochemical limitations for Chloritoid appearance in metapelites, whole rock composition of the area is suitable for Chloritoid formation. Since P, T ...
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Chloritoid as one of the common metamorphic mineral in low to medium grade metapelites, is absent in metapelitic rocks of Hamedan area. Comparing with geochemical limitations for Chloritoid appearance in metapelites, whole rock composition of the area is suitable for Chloritoid formation. Since P, T and X are in appropriate range for Chloritoid, the role of fluid could be important. Microscopic investigations show that all metapelitic rocks are in equilibrium with graphite and fluid composition is combination of CO2 and H2O. Based on estimated P and T, highest portion of H2O in the fluid, could be 0.9. Although this is highest approximation, it can conclude that for Chloritoid appearance, XH2O in fluid must be more than 0.9. Since in the Hamedan area staurolite is widespread and Chloritoid is absent - considering almost same composition between chloritoid and staurolite - the composition of fluid is more important. There are many doubts in geochemical limitations for Chloritoid appearance. Considering the results of this study and in the case of attention to fluid composition, geochemical limitations will change and Chloritoid could appear in many rocks, as its higher temperature equivalent, staurolite.
Original Research Paper
M. H. Mir Yaghoobzadeh; M. R. Ghanbarpour
Abstract
Snow cover was one of important parameter in snow melt runoff model. Because snow telemetry in mountainous basin is difficult, remote sensing image is an alternative object in snow cover mapping. Snow cover maps derived in remote sensing imagery is one of the important data entries in snow melt runoff ...
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Snow cover was one of important parameter in snow melt runoff model. Because snow telemetry in mountainous basin is difficult, remote sensing image is an alternative object in snow cover mapping. Snow cover maps derived in remote sensing imagery is one of the important data entries in snow melt runoff models. MODIS imagery was selected for deriving snow cover maps in this study. In order to investigate the difference in reflectance bands, vertical profile in each image was generated. Capability of NDSI in MODIS imagery was confirmed. Finally snow melt runoff simulation in Karaj Dam basin was carried out as the fundamental remote sensing data capabilities. Result showed that the NDSI using threshold on band 2 and band 4 demonstrates an efficient relation in snow cover maps. Moreover simulation of snow melt in 2001-2000 with the coefficient of R2=0.4678 and ∆v=0.1292 m3/s indicated. The high accuracy of snow cover maps derived from remote sensing data.
Original Research Paper
A. H. Sadr; Mohammad Mohajjel; A. Yasaghi
Abstract
The style of deformation changes from the hinterland (Sanandaj-Sirjan zone) to the foreland (Zagros) through the Zagros Orogen containing thick-skinned and thin-skinned deformation respectively. NW-SE trending thrust faults dipping to northeast have carried the older rock sequences to the surface. The ...
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The style of deformation changes from the hinterland (Sanandaj-Sirjan zone) to the foreland (Zagros) through the Zagros Orogen containing thick-skinned and thin-skinned deformation respectively. NW-SE trending thrust faults dipping to northeast have carried the older rock sequences to the surface. The Zagros collision zone could be divided into two distinct parts based on deformation mode that is separated by the Main Zagros Thrust. The southwestern part contains imbricate thrust sheets instead, to the northeastern part large amount of shortening is documented by basement deformation with duplex structures. Abundant crystalline deep origin thrust sheets have transported (2 up to 20 km) the metamorphic rock units upon the Zagros suture zone by gravity or tectonic forces. Despite the collision thrust faults, both NW oriented (Main Recent Fault) and NE oriented (named here Azna Fault) basement wrench faults have also activated and caused different style and amount of deformation in the collision zone.
Original Research Paper
R. Kohansal; S. Zolfaghari; M. Ghahraie - Pour
Abstract
The study area is a small part of the Sabzevar structural zone and confined between Semnan and Khorasan provinces. The oldest sedimentary rocks of this region are Middle Jurassic in age with horizons of calc-alkaline rhyolitic- rhyodacitic lavas in between. First appearance of alkaline basaltic lavas, ...
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The study area is a small part of the Sabzevar structural zone and confined between Semnan and Khorasan provinces. The oldest sedimentary rocks of this region are Middle Jurassic in age with horizons of calc-alkaline rhyolitic- rhyodacitic lavas in between. First appearance of alkaline basaltic lavas, intruded by diabasic dikes in this region appeared along with Early Cretaceous limestone. Late Cretaceous rocks include voluminous calc-alkaline rhyodacitic- rhyolitic and trachyandesitic composition as lavas and dikes, and basaltic dikes with abundant pinkish-cream plagic limestone. This has been overlaid by Paleocene rocks. Harker element variation diagrams indicate contamination and differentiation of basic magma, from a depleted mantel, which is also confirmed with spider diagrams. Tectonomagmatic signatures of Middle Jurassic and Upper Cretaceous volcanic rocks are similar to volcanic arc and syn-collisional magmas which have formed by tectonic movements of Middle Cimmerian and Laramid. Furthermore Austrian orogeny has led to development of Lower Cretaceous basic volcanic rocks within continental plate that are demonstrated in binary and ternary trace element diagrams. The Late Cretaceous-Early Tertiary Laramid orogeny leads to closure of the Neo-Tethys basin by folding and uplifting of the study area. Just in the Marri area lack of intrusive rocks pertaining to mature ophiolitic assemblage, presence of volcano-sedimentary rocks in the upper part of this succession from one side, and abundance of pressure and strike-slip faults with similar mechanism of Doruneh fault from other side, suggest an old suture zone and fast closure of this part of Doruneh- Kashmar trough, and development of colored melange in this area.
Original Research Paper
H. Aghajani; A. Moradzadeh; H. Zeng
Abstract
Estimation of depth and horizontal location of anomalous bodies plays an important role for selecting exploration wells location. There are many methods for depth estimating, and most of them use high-pass filters. The Normalized Full Gradient (NFG) method is one of these methods that use Fourier series ...
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Estimation of depth and horizontal location of anomalous bodies plays an important role for selecting exploration wells location. There are many methods for depth estimating, and most of them use high-pass filters. The Normalized Full Gradient (NFG) method is one of these methods that use Fourier series to remove deficiencies and eliminate the oscillations which appear on the downward continuation when passing through center of an anomalous body. In this paper, the main goals is calculation of NFG and present a new method for determining optimum number of Fourier terms and use them for synthetic and real two and three dimensional field data. The obtained results on synthetic data indicate that the estimated location and depth of the model is in 10 percent error with the real. The NFG method has also applied on two sets of real field gravity data to determine the location and estimate depth of Humble salt dome (USA) and massive sulfide mineralization of Mobrun (Canada). For the first field data set the NFG has provided a depth to the centre equal to 4.8 km and for the second case the depth to the top section of mineralized body has been estimated 17 meters and its continuation to a depth more than 70 meters has also been confirmed. The obtained results of the NFG method on real field data in each case are in good agreement to those provided by other independent information arises from drilling and other geophysical methods. The above matter clearly illustrates that the NFG method is able enough to locate anomalous bodies and estimate their burial depth precisely.
Original Research Paper
S. R. Shadizadeh; M. Zoveidavianpoor
Abstract
Abadan Refinery is located between Arvandrud and Bahmanshir rivers. These rivers supply urban, industrial and agricultural water of Abadan city. During the war between Iran and Iraq, leakage of large amounts of oil and its refined products from storage tanks, pipe lines, and refinery units of Abadan ...
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Abadan Refinery is located between Arvandrud and Bahmanshir rivers. These rivers supply urban, industrial and agricultural water of Abadan city. During the war between Iran and Iraq, leakage of large amounts of oil and its refined products from storage tanks, pipe lines, and refinery units of Abadan refinery to surrounding environment occurred. Also, leakage of petroleum and its products during the operation of Abadan refinery to surrounding environment led to conduct a research for determination of oil pollution extension of underground layers in Abadan refinery. Utilization of clays as natural geological barriers in environmental application and pollution control has been widely recognized. Abadan city was formed by recent Estuarine; these alluviums had a diverse variety in grain size and material. In the case of dominant presence of clay in underground layers, petroleum pollution control hypothesis of Abadan refinery is confirmed. In order to prove the above hypothesis the following items were conducted: 1) determination of material type of underground layers, 2) determination of petroleum pollution in underground layers and defining the oil saturation of the cores, and 3) determination of petroleum pollution in underground waters by one year sampling of underground waters along with measurement of piezometric head of groundwater monitoring wells. Location of twenty groundwater monitoring wells was investigated by considering petroleum leakage to surrounding area during and after war. Geological underground layers of Abadan refinery was determined from coring during drilling of the groundwater monitoring wells. The results of this investigation has shown that the material type of underground layers of Abadan refinery had a significant role to encapsulate petroleum leakage, in such a manner that leaked petroleum was observed in all of the drilled boreholes. On the other hand floated leaked petroleum on groundwater was observed just in two groundwater monitoring wells. These two polluted groundwater monitoring wells were shown to be from leakage of recent activities of Abadan refinery. Finally the results show that the majority of existing petroleum in underground layers of Abadan refinery was absorbed by clay
