M Agh-Atabai
Abstract
The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and ...
Read More
The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and multifractal analyses have been applied for quantification of earthquakes pattern in the GolestanProvince. For this aim, the correlation dimension, generalized multifractal dimensions and singularity spectrum f (αq) have been calculated using the correlation integral and fix-mass methods. The epicentral analyses of earthquakes showed that their distribution has two scaling ranges with two different patterns and mechanisms controlling the earthquake pattern in these scales. It seems that the movements of small faults and fractures, which caused increasing the correlation dimension (1.84) and heterogeneity of multifractal structure, controlled the small scale. However, at large scale, the distribution of earthquakes is mostly controlled by the main structural trends, which in turn results in becoming almost linear their correlation dimension and also more homogeneous multifractal structure.
M .A. Mokhtari; H. Moein Vaziri; M.R. Ghorbani; M. Mehr Parto
Abstract
Kamtal intrusion is located in East Azarbaijan province, NW of Iran, near the Armenia border. The Kamtal intrusion consist of an acidic part with monzogranitic composition and an intermediate- basic part which compositionally composed of monzonite, monzodiorite, quartz monzonite, quartz monzodiorite ...
Read More
Kamtal intrusion is located in East Azarbaijan province, NW of Iran, near the Armenia border. The Kamtal intrusion consist of an acidic part with monzogranitic composition and an intermediate- basic part which compositionally composed of monzonite, monzodiorite, quartz monzonite, quartz monzodiorite and gabbro. Gabbroic rocks exist in the form of small lenses in the southeast of Kamtal intrusion within the intermediate part. The intermediate- basic part has been intruded by the acidic part. Both acidic and intermediate parts are high-K calc-alkaline, metaluminous in character and classified as I-type granitoids; while, the gabbros have tholeiitic nature.
Both acidic and intermediate rocks show a LREE rich pattern and high LREE/HREE ratio. These two parts have differences in MREE enrichment. From similarity in REE patterns of acidic and intermediate rocks a genetic relation can be discerned. Negative anomalies of Nb and Ti can be seen in all rock phases of the Kamtal intrusion, representing the subduction zone setting. Comparison of trace element variations with those of granitoid rocks of different tectonic settings show similarities between Kamtal intrusion and Andean volcanic arc granitoids. Furthermore, Kamtal intrusion can be classified as VAG based upon tectonic setting discrimination diagrams. It is concluded that, Kamtal intrusion probably is the result of Neotethys oceanic crust subduction beneath the Caucasus continental plate.
M Delavari; S.A Amini; A Saccani
Abstract
Tertiary volcanism in east and northeast of Nehbandan, eastern Iran, includes mostly basic-intermediate associations. They are characterized by sodic (1<Na2O/K2O) compositions and contain both low-k tholeiitic and calk-alkaline series. Based on petrographic, mineral chemistry and whole-rock geochemical ...
Read More
Tertiary volcanism in east and northeast of Nehbandan, eastern Iran, includes mostly basic-intermediate associations. They are characterized by sodic (1<Na2O/K2O) compositions and contain both low-k tholeiitic and calk-alkaline series. Based on petrographic, mineral chemistry and whole-rock geochemical evidences basalts can be classified into two groups; arc-related calc-alkaline basalts (CAB) and low-K tholeiites (LKT). The evolutionary trends of some major and trace elements vs. SiO2 and also chondrite-normalized rare earth element (REE) patterns represent gentic relation between low-K tholeiitic intermediates and LKT but reject calkalkaline intermediate generation by magmatic evolution from CAB. In MORB-normalized multi-element patterns, negative anomally of high field strength elements (HFSE) and enrichment of large-ion lithophile elements (LILE) suggest subduction zone-related tectonomagmatic setting for basic-intermediate associations in which compositional change from LKT to CAB is accompanied by the evolution of arc system. This scenario in Sistan suture zone is interpreted as subduction continuation of Sistan oceanic lithosphere in Tertiary.
M. Memariani; H. Kermanshahi; M. R. Kamali
Abstract
With respect to distribution of Surmeh Formation in Persian Gulf region, this formation may act as candidate source rock for hydrocarbon accumulation in this region. A comprehensive geochemical analysis including Rock-eval Pyrolysis, Gas Chromatography (GC), Gas Chromatography – Mass Spectrometry ...
Read More
With respect to distribution of Surmeh Formation in Persian Gulf region, this formation may act as candidate source rock for hydrocarbon accumulation in this region. A comprehensive geochemical analysis including Rock-eval Pyrolysis, Gas Chromatography (GC), Gas Chromatography – Mass Spectrometry (GC-MS), were carried out on cuttings, in order to determine its hydrocarbon potentiality. Based on Rock-Eval data, the organic matter of the Surmeh formation is type II and III kerogen, with low maturity being at the end of diagensis stage. It exhibits a poor source rock characterization with low content of TOC. A close similarity can be seen, between organic matter extracted from Surmeh sample with that of oil sample collected from Upper Dariyan, Lower Dariyan and Maudud reservoir in the field. Biomarker results indicate that an open marine and few terrestrial input source rocks deposited in an anoxic condition with carbonate origin. Based on geochemical investigations Surmeh Formation isn't suitable source rock in the study area locally. Biomarker derived from rock extracts and trapped oils indicated that they share the same origin and were stained by laterally migrating oils from distant area.
M. Abdollahy; S. M. J. Koleini; A. Ghaffari
Abstract
Cyanidation process is one of the most important and widespread hydrometallurgical technologies used in the extraction of gold and silver from ores and concentrates. Some of the most effective parameters on cyanide leaching are sodium cyanide concentration, dissolved oxygen, solid percent, pH, particle ...
Read More
Cyanidation process is one of the most important and widespread hydrometallurgical technologies used in the extraction of gold and silver from ores and concentrates. Some of the most effective parameters on cyanide leaching are sodium cyanide concentration, dissolved oxygen, solid percent, pH, particle size, retention time and agitation speed. In this article the effect of these parameters on the recovery of gold, silver and mercury from Pouya Zarkan Aghdareh ore has been studied to determine the optimum conditions using Taguchi exprimental design method. The experiments at the screening step based on L16 orthogonal array indicated that the effective parameters on gold, silver and mercury recovery such as sodium cyanide, pH, solid percent in pulp, d80 and retention time were obtained equal to 900 g/t ore, 10, 42%, 53 μm and 30 h, respectively. The experiments at the optimization step based on L18 orthogonal array indicated that d80 on gold recovery and retention time on silver and mercury recovery were the most effective parameters. Finally the optimum conditions for gold, silver and mercury recovery were obtained for parameters such as sodium cyanide, pH, solid percent in pulp, d80 and retention time equal to 1000 g/t ore, 10.3, 46%, 37 μm and 40 h, respectively. At this conditions gold, silver and mercury recovery were equal to 91.42±1.02, 54.31±1.24 and 19.50±0.66 percent, respectively.
R. SH. Shahabi; R. Kakaie; M. H. Basiri
Abstract
Mineral Resources which can be regarded as a best potential opportunity to sustainable development of the country. Consequently appropriate investment in exploitation of these reserves can achieve high value added to the most industries. Therefore, it is necessary to recognize the priority of minerals ...
Read More
Mineral Resources which can be regarded as a best potential opportunity to sustainable development of the country. Consequently appropriate investment in exploitation of these reserves can achieve high value added to the most industries. Therefore, it is necessary to recognize the priority of minerals for future investments. In this paper, the Analytical Hierarchy Process, in which a complex problem is modeled in a hierarchical structure showing the relationships of the goal, objectives (criteria) and alternatives, is used to recognize high priority 33 minerals for future investment with regards to the 6 criteria and 29 sub-criteria. For this purpose, on the bases of interview with mineral sector experts weights of criteria are calculated and then the piority of each mineral is determined for investments. The results show that copper, Iron, Phosphate, lead and zinc, coal, gold have high priority for future investments.
F. Taghizadeh-Farahmand; F. Sodoudi; M. R. Gheitanchi; A. Kaviani
Abstract
We compute p receiver functions (RF) to investigate the crustal thickness and Vp/Vs ratio beneath the northwest of Iran and map out the lateral variation of Moho depth under this region. We selected data from teleseismic events (Mb≥5.5, 30˚>r > 95˚) recorded since 2000 to present at ...
Read More
We compute p receiver functions (RF) to investigate the crustal thickness and Vp/Vs ratio beneath the northwest of Iran and map out the lateral variation of Moho depth under this region. We selected data from teleseismic events (Mb≥5.5, 30˚>r > 95˚) recorded since 2000 to present at 8 three component short period stations from Tabriz teleseismic network. RF method is now a well-known tool for studying crustal thickness when such a complete data set is available. As the p-to-s conversion points at the Moho is laterally close to the stations, the Moho depth estimation is less affected by lateral velocity variations and thus provides a good point measurement. First of all, we calculated RFs for each station and then the Moho depth will be estimated only from the delay time of the Moho p-to-s conversion phases. Then we used an H-Vp/Vs stacking algorithm (Zhu & Kanamori ,2000 ) to estimate crustal thickness and Vp/Vs ratio under each station from P-to-S converted waves in receiver functions. The best value for H and Vp/Vs ratio is found when the three phases (Ps and crustal multiples) are stacked coherently. The average Moho depth is approximately 48 km and varies from 38.51 to 53.51 km. Deeper and shallower Moho is found under the western and eastern stations beneath SHB and SRB stations respectively. The northwest Iran's crust has an average Vp/Vs ratio of 1.76, with higher ratio of 1.820.03 in Tabriz station and lower ratio of 1.73 0.03 in Azarshahr station.
F Sarjoughian; A Kananian; J Ahmadian
Abstract
The alkali feldspars and plagioclases in the Kuh-e Dom intrusive rocks show compositionally and microtexturally zoning structure. The feldspar crystals in the various lithologies such as granite- granodiorite samples, diorite- gabbro samples and relatively high frequency microgranular mafic enclaves ...
Read More
The alkali feldspars and plagioclases in the Kuh-e Dom intrusive rocks show compositionally and microtexturally zoning structure. The feldspar crystals in the various lithologies such as granite- granodiorite samples, diorite- gabbro samples and relatively high frequency microgranular mafic enclaves existing in the acidic intrusion were analyzed using electron microprobe. The results of the microprobe analysis in the acidic, basic- intermediate rocks and enclaves indicated the normal and reverse zoning in the samples. The chemical compositions of plagioclases ranges from albite (An 9.4) in the rim to labradorite (An: 50.6) in the core for acidic rocks, and from andesine (An: 30.5) in the rim to labradorite (An: 56.4) in the core for the basic- intermediate rocks, and from oligoclase (An: 19.8) to labradorite (An: 66.5) in the enclaves. The frequently of rare elements such as Ba, Sr, Fe and Mg in the feldspars show various and oscillatory patterns. The oscillatory pattern of the major and minor elements from core to rim in the feldspar crystals suggests an effective role of magma mixing phenomena in forming of the Kuh-e Dom intrusion.
F. Yamini-Fard; A. S-Moradi; M. Hosseini; R. Norouzi
Abstract
From June 2004 to December 2008 low seismic activity was recorded near North-Tehran, Taleghan and Kahrizak faults and inside of Tehran city. In contrast, seismic activity along Mosha, Garmsar and North-Alborz faults is considerable. Generally seismic activity decreases from 51 degrees longitude to west. ...
Read More
From June 2004 to December 2008 low seismic activity was recorded near North-Tehran, Taleghan and Kahrizak faults and inside of Tehran city. In contrast, seismic activity along Mosha, Garmsar and North-Alborz faults is considerable. Generally seismic activity decreases from 51 degrees longitude to west. Two earthquakes with 15 and 17 km depth were located in the west of Tehran city. The calculated focal mechanism for one of them is pure strike-slip. High seismic activity is observed along Mosha fault close to Damavand, Boumehen cities and Lavasant-e-Bozorg region. Calculated focal mechanisms along this fault includes both strike-slip, and reverse mechanisms that implies transpression motion, dominantly left-lateral slip along this fault that continued to Lavasanat region in south of the eastern end of the North Tehran fault. Precise location of some events shows depth range of 4-32 km. Generally, calculated focal mechanisms in studied region include both strike-slip and reverse mechanisms and seems that in southern part, approaching Central Iran, reverse mechanisms are dominant. It implies slip partitioning in southern margin of Central Alborz.
A.M Azhdarpour; M.R Nikudel; S.D Mohammadi
Abstract
Rusted bottles and ragged car tires are good examples of modern waste materials, which can cause significant environmental concerns. Despite all environmental issues of these materials they could be used as a reinforcement material in weak soils. This strategy not only reduces the volume of waste materials ...
Read More
Rusted bottles and ragged car tires are good examples of modern waste materials, which can cause significant environmental concerns. Despite all environmental issues of these materials they could be used as a reinforcement material in weak soils. This strategy not only reduces the volume of waste materials but also can make them valuable. The results of laboratory tests have shown that using PET crushed particles can improve the engineering properties of sandy soils while for rubber fibers these changes are not as positive as PET particles. In fact using rubber fibers has damaged some of the engineering characteristics of the sandy soils.
M Allameh; Z Sardar
Abstract
Aitamir Formation is one of the formations in sedimentary basins of Koppeh-Dagh in the north east of Iran. This formation has been made of a sandstone part in the lower and a shale part in the upper. Both the part are Glauconitic and often seen in Olive-green color. This research is on a section of a ...
Read More
Aitamir Formation is one of the formations in sedimentary basins of Koppeh-Dagh in the north east of Iran. This formation has been made of a sandstone part in the lower and a shale part in the upper. Both the part are Glauconitic and often seen in Olive-green color. This research is on a section of a Aitamir formation based on Palynomorphs which has been conducted on the route from Mashhad to Kalat-e-Naderi, isn the edge of Zavin village with the thickness of 506 meters and the coordinates 36°43̒45.42" north latitude, and 59°57̒5.56"east longitude. 40 samples of this section have been gathered and 120 Palynological slides have been prepared. The study of these slides has resulted in the identification of 28 genera and 47 species of Dinoflagellates. Regarding the identified Dinoflagellates, the age of Aitamir formation in the mentioned Albian-Cenomanian section was determined. The study of the factors involved in preservation of organic materials shows the low to moderate levels of oxygen conditions, with low deposition and an inner to the outer Neritic environment for an Aitamir formation in the mentioned section. Based on the studies that have been done, three Palynofacies were identified for the Aitamir formation in Zavin section.
M. Asgharian Rostami
Abstract
In order to study the Gurpi formation for biostratigraphical purposes the 310 meters thick section was sampled at Mish-khas Sectiona, Ilam province. The sequence is mainly made up of monotonous marl, limy marl and Limestone and contains two formal members of Lopha (with brachiopod, Echinoid and Bivalve) ...
Read More
In order to study the Gurpi formation for biostratigraphical purposes the 310 meters thick section was sampled at Mish-khas Sectiona, Ilam province. The sequence is mainly made up of monotonous marl, limy marl and Limestone and contains two formal members of Lopha (with brachiopod, Echinoid and Bivalve) and Emam-Hasan. Lower boundary Gurpi formation is contineous with Ilam Formation.At boundary both formation, Gray marl Gurpi formation located on limestone and limy marl at Ilam formation and upper boundary is continus with Pabdeh Formation. Sixty seven species belonging to 26 genera were identified and fourteen biozones were differentiated. These are: 1.Globotruncanita elevata partial range zone, 2. Globotruncana ventricosa interval zone, 3.Radotruncana calcarata total range zone, 4. Globigerinelloides subcarinatus partial range zone, 5.Globotruncana aegyptiaca partial range zone, 6. Gansserina gansseri partial range zone, 7.Contusotruncana contusa partial range zone, 8. Pseudotextularia intermedia partial range zone, 9. Racemiguembelina fructicosa partial range zone, 10.Pseudoguembelina hariaensis partial range zone, 11. Pseudoguembelina palpebra partial range zone, 12. Praemurica uncinata interval zone, 13. Morozovella angulata- Globanomalina pseudomeandri interval zone, 14. Globanomalina pseudomenardi total range zone. According to the planktonic foraminifera the formation encompases Lower Campanian to late Paleocene (Thanetian). lack of Marginotruncanid and Dicarinella asymetrica showing lower campanian for bas of section.There is distinct hiatus in Cretaceous-Paleogene boundary based on paleontology and sedimentology evidence. Analysis of Planktonic and Benthic foraminifers' assemblage at this section with Cretaceous biostratigraphical provinces is indicating a close similarity with those of Tethyan provinces.
Kh. Hashemi; B. Oveisi; A. Saeedi
Abstract
Young deformations and folds are one of the impressive characteristics of Zagros simple folded belt. The studied structure is Hormud fault-related fold which is situated in the coastal Fars and the southward of Lar town. In order to illustrate the geometry of the studied structure and its kinematic relationship ...
Read More
Young deformations and folds are one of the impressive characteristics of Zagros simple folded belt. The studied structure is Hormud fault-related fold which is situated in the coastal Fars and the southward of Lar town. In order to illustrate the geometry of the studied structure and its kinematic relationship with north and south structures, a structural cross section with ~27 km length from NE to SW was prepared. This study showed that Hormud anticline has been formed in the footwall of Lar fault, synchronous with kinematic reorganization in the core of Lar anticline and increasing horizontal stresses. Interpretation of crustal young deformations in the vicinity of the footwall of Lar fault indicates that Hormud anticline is growing in the form of a constant limb length detachment fold. Estimation of relative shortening rate (0.9± 0.2) for south limb of Hormud anticline is showing its fast growth in the form of a rocket fold which was associated by fast propagation of Hormud fault toward the surface. As a consequence of this process, kinematic model of Hormud anticline changes from a constant limb length detachment fold to a shear fault bend fold. Estimations predict 0.7 ± 0.1 mm/yr relative uplift rate for young Hormud anticline in its crest.
A.H. Kokabi Nezhad; Z. Purabrishami; Kh. Tehrani
Abstract
One of Hipparion species which has complete characters of cranium and maxillary with teeth found during excavation is H.primignium. Since this sample is the only complete one in the world, (of course without mandible) with special species characters we can call it Homeotype. Because of finding this species, ...
Read More
One of Hipparion species which has complete characters of cranium and maxillary with teeth found during excavation is H.primignium. Since this sample is the only complete one in the world, (of course without mandible) with special species characters we can call it Homeotype. Because of finding this species, pyroclastic sediments of Maragheh would be dated upper Astracian, so Maragheh informal formation which in the past was thought to be as old as vallencian- Trulain, seems a bit older. Because the mentioned samples were also found in Samus and Pikermi in Greece, so we can say these two regions have vertebrate familiarities in fossils fauna and other characters like paleogeography, biochronology and biogeography in late Miocene- early Pliocene.
H. A. Tajeddin; E. Rastad; A. Yagoubpour; M. Mohajjel
Abstract
Barika deposit is the first and only recognized gold (and silver) rich – massive sulfide deposit in Iran which is located at 18 km east of Sardasht city, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are volcano sedimentary metamorphosed rocks in green ...
Read More
Barika deposit is the first and only recognized gold (and silver) rich – massive sulfide deposit in Iran which is located at 18 km east of Sardasht city, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are volcano sedimentary metamorphosed rocks in green schist facies, and include association of metaandesite, metatuffite, phyllite and slate rocks, among which the metaandesitic unit (KMv1) is host rock of the deposit. Ore mineral assemblages in stratiform part of the deposit, which contain massive and banded pyrite and barite associated with subordinary silica bands, are very variable in composition and consist of pyrite, sphalerite, galena, stibnite and a variety of sulfosalt minerals and electrum. Ore mineral assemblage in silicic veins in stringer zone, are simpler and consist of pyrite, galena, sphalerite, tetrahedrite and rare chalcopyrite. Average gold and silver grades in stratiform ore are 4.2 and 260 g/t respectively and in silica stringer veins are 0.7 and 30 g/t. Base metal content in both part of the deposit is less than 1%. Lithotectonic study and trace and rare earth elements diagrams associated with Ce/Pb and Nb/U ratios of the metavolcanic rocks in the deposit area indicate that the rocks were generated from a lithospheric mantle source in the active continental margin of the SSZ. A geochemical study of Barika deposit reveals that distribution patterns and correlation coefficient of ore elements in parts of the Barika stratiform ore and stringer zone are completely in correlation with an undeformed massive sulfide deposit. The geochemical documents indicate that despite the metamorphism and highly deformation on the deposit, the primary distribution patterns and proportion of the ore elements are well conserved, as geochemical characteristics of the Barika deformed deposit is as well as correlated with an undeformed gold- rich volcanogenic massive sulfide deposit. However there is clear textural evidence for remobilization of As, Sb, Ag and Pb minerals together with Au in Barika deposit, but, remobilized constituents of the ores do not appear to have moved beyond the margins of the ore bodies and primary metal zonation.
F Kamranzad; L Moussavi; M Mojarab; H Memarian
Abstract
In this study,attenuation behavior of moderate to large earthquake aftershock sequences occurred in Iranian plateauhas been investigated according to the empirical Omori Law. Due to proper recordings of instrumental earthquakes from 1990 to 2012, important earthquakes of this period were selected. After ...
Read More
In this study,attenuation behavior of moderate to large earthquake aftershock sequences occurred in Iranian plateauhas been investigated according to the empirical Omori Law. Due to proper recordings of instrumental earthquakes from 1990 to 2012, important earthquakes of this period were selected. After determination of aftershock sequences using temporal-spatial window defined by Gardner &Knopoff (1974), 14 sequenceshaving enough recordings and appropriately distributed over the Iranian plateau were investigated in terms of attenuation behavior curve.Therefore, the Omori curve and parameters (p, c and k)were plotted and calculated for each sequence. Results show that for the Iranian plateau earthquakes, p-values range between 0.39 and 2.7, parameter c values vary from 0.01 to 5, and paremeter k shows values in the range of 10 to 1427.4. This high variability is taken to indicate not only a variety of aftershock occurrence patterns in the Iranian plateau, but also an incomplete and inhomogeneous earthquake catalog.By using the present database, therefore, it is not easily possible to have a zonation based on temporal attenuation behavior of aftershock activitiesover the Iranian plateau. However, the estimations of aftershock attenuation rate for each locality can be used to analyze seismic hazard. Present study showed that the p-values and hence the aftershock attenuation rates in the Alborz and Zagros regions are greater than those in the eastern and central parts of Iran. The higher the rate, the greaterthe energy release, which means a shorter time to gain background seismicity. This result is comparable and consistentwith the amount of energy released in theseismotectonic zones of the Iranian Plateau. Moreover, 7 out of 14 earthquake sequences have secondary aftershocks, which give two values for each Omori parameters. Results demonstrated that with a higher earthquake magnitude, the occurrence of the next big event as well as secondary aftershocks is more likely. Furthermore, for the 7 sequences with secondary aftershocks, a trend of P2 variations is observable. P2 is more than 2.5 for 3 of these sequences that have magnitudes above 7 and occurred along the Iranian plate boundaries. For the other 4 intraplate events, which have magnitudes less than 7, P2 is less than 2. This might be due to a magnitude change or tectonic setting and distance of hypocenter to the main fault nodes. Resultsalso showed that the c and k parameters are highly affected by number of recordings in the catalog. A more complete and homogeneouscatalog would produce well-constrained values for these parameters,which in turnmakes the analysis of the seismicity and physics of the fault zone more accurate.
M Khalatbari Jafari; M Mirzaie; M. R Jannessary
Abstract
The plutonic crustal sequence of Garagoli-Bagjar, located in NE Sabzevar, is a part of ophiolitic association in the outer part of Central Iran microcontinent. This sequence comprises cumulative olivine gabbro, pyroxene gabbro, isotropic gabbro, foliated gabbro and diabasic sheeted dike complex, cross ...
Read More
The plutonic crustal sequence of Garagoli-Bagjar, located in NE Sabzevar, is a part of ophiolitic association in the outer part of Central Iran microcontinent. This sequence comprises cumulative olivine gabbro, pyroxene gabbro, isotropic gabbro, foliated gabbro and diabasic sheeted dike complex, cross cut by the wherlitic intrusion, pegmatite gabbro and plagiogranite as small bodies, dikes and veins. This sequence is comparable to upper gabbroic part of the well known ophiolite complex. These rocks construct a large tectonic slics thrusted over the serpentinized peridotites and tectonically located under serpentinites. The cumulative gabbros change gradually to isotropic gabbro upwards and at the same time isotropic gabbro change generally to diabasic sheeted dike complex. The structural measurements of magmatic layering and strike of sheeted dikes, wherlitic intrusions, pegmatite gabbro and plagiogranite revealing E-W direction in the north of Qaragoli and N-S direction in SW Solymanieh might be comparable to the formation of plutoinc oceanic crust in fractures zone. The microscopic studies exhibit that mesocumulate to heteradcumulate textures are abundant which indicate the open magmatic chamber of the supra-subduction zones. The crystallization trends show diversity from olivine-plagioclase-clinopyroxene-orthopyroxene-amphibole trend (MORB like) to olivine-clinopyroxene-orthopyroxene-plagioclase-amphibole trend (as arc type). The study of the chemical analyses indicates diverse compositions and primitive mantle normalized spider diagrams show depletion of Nb with different enrichement of LREE. The low-Ti character, locations in arc related cumulate and non cumulate fields, island arc to MORB tectonomagmatic setting remark their supra-subduction origin which formed in Late Cretaceous.
H. Vaziri-Moghaddam; A. Safari; S. Shahriari; A. Khazaei; A. Taheri
Abstract
In order to study the biostratigraphy and palaeoecology of the Maestichtian deposits (Tarbur and Gurpi formations) in High Zagros, Gardbishe section in south of Borojen was selected. The Tarbur deposits in this region are mainly composed of carbonate and clastic a rock which has been overlaind by Gurpi ...
Read More
In order to study the biostratigraphy and palaeoecology of the Maestichtian deposits (Tarbur and Gurpi formations) in High Zagros, Gardbishe section in south of Borojen was selected. The Tarbur deposits in this region are mainly composed of carbonate and clastic a rock which has been overlaind by Gurpi Formation. The lower contact of this formation is lower red unit as conformable contact. The Gurpi Formation is lithologically composed of marl which has been overlaind as a disconformable contact by Shahbazan dolomites. The biostratigrphic data based on benthic and planktonic foraminifera and rudists represents the late Maestrichtian age for the section. Two biozones were identified in Maestrichtian deposits including: Omphalocyclus-Loftusia assemblage zone, Contusatruncana contusa-Recemiguembelina fructicasa zone. In general, the suitable environmental conditions for diversity, frequency and increase in size of some fossils such as Loftusia and in the absence of some other fossils such as Orbitoides and Lepidorbitoides in this region can be related to augmentation of nutrients and entering the detrital and silica sediments due to river injection and runoff and consequently to the eutrophic conditions formed in the basin.
K. Nejad. Afzali; F. Bayatani; E. Moghimi
Abstract
Coastal region are influenced by land and sea. Geomorphologic coast features are related to sea level change, regional river regime, erosion processes, sedimentation, climate change, geological outcrops and weathering and tectonics. Tom bolo, lagoon and barrier are geomorphologic coast features that ...
Read More
Coastal region are influenced by land and sea. Geomorphologic coast features are related to sea level change, regional river regime, erosion processes, sedimentation, climate change, geological outcrops and weathering and tectonics. Tom bolo, lagoon and barrier are geomorphologic coast features that can be seen in Bir coast of Iran. Therefore, recognizing the producing mechanism and their changes, leads supervisors to have better management, and do their best for civil and improving planning in coast area. In this research in addition to field studies and sampling, aerial photos 1/40000(1993), topographic maps 1/20000, high resolution images (ETM and IRS) 1998, 2005, 2008 were used. It is concluded that the area is tectonically active, sedimentation; erosion processes, river regime and sea level change are caused to the Tom bolo, Lagoon and Barrier in Bir coast. Surveying the forms, sediment shows an obvious computation between marine currents as constructive process of Tom bolo, lagoon and barrier, and rivers as destructive process in Bir coast.
Geophysics
mohammad rasool nikbakhsh; Mir Sattar Meshinchi Asl; Hamidreza Siyahkohi; Mohsen Oveisy Moakhar
Abstract
An important goal in mining exploration is the estimation of the depth and the thickness of the causative source. According to this simplification, several methods have been developed for interpreting magnetic field anomalies. In this article, the Hilbert transform has been used to calculate the ...
Read More
An important goal in mining exploration is the estimation of the depth and the thickness of the causative source. According to this simplification, several methods have been developed for interpreting magnetic field anomalies. In this article, the Hilbert transform has been used to calculate the depth and thickness of 3-D thin plate anomalies. The Hilbert-Fourier transform performs an important role in analytic signals. Since the total magnetic fields anomalies function has the characteristics necessary for an analytic function, i.e. its real and imaginary parts form a Hilbert transform pair, the function can be used to interpret networked data in terms of three-dimensional origins. The Hilbert transform does not change the amplitude of a function but shifts the phase by and for positive and negative phase values, respectively. This paper uses a two-dimensional Hilbert transform and a 3-D analytic function to calculate the depth of a thin three-dimensional plate modeled based on the method of Talwani for noisy data and without noise data. The results show that the estimated depth values derived from the Hilbert transform method are associated with an error of less that 3% for data without noise, and an error of 8% for data of 15% noise. . This method was also tested on the real magnetic anomaly data from the Kheirabad iron mine located at 5 km NE of Golgohar, Sirjan, Iran. The results were compatible with the Euler method and with drilling information of the mine. The obtained depth is in good agreement with the actual depth, which confirms the application of the Hilbert transform for the interpretation of field data and estimation of magnetic anomalies depths.
SH. Gholipouri; P. Ghazanfari; M. Almasian; N. Jalali
Abstract
Vardeh drainage basin is located at north of Karaj and belongs to Central Alborz structural zone and its climate is semi-humid. The area of Vardeh basin is 68,97km2. Formations in this basin mainly include shale, tuffaceous shale, tuffaceous sandstone and limestone. The age of Kahar Formation is Precambrian, ...
Read More
Vardeh drainage basin is located at north of Karaj and belongs to Central Alborz structural zone and its climate is semi-humid. The area of Vardeh basin is 68,97km2. Formations in this basin mainly include shale, tuffaceous shale, tuffaceous sandstone and limestone. The age of Kahar Formation is Precambrian, the oldest formation and quaternary alluvial deposits are the youngest deposits at this basin. The aim of this study is Investigation of susceptibility of formations to erosion with qualitative methods, assessment of physiographic and geomorphology and quantitative ways, MPSIAC model and sedimentary yield. In this research, library studies, field surveys, interpreting Arial photos were carried out. The collected data taken into account from geometry factors, in V1 sub – basin minimum slope and altitude and in v7-2 maximum slope and altitude. Vardeh basin is divided into mountain (M,m), hills(h), and alluvial deposit (Qal,Qt). Mio fancies forms the most area of the basin. In MPSIAC model the effect of nine and EPM model the effect of 4 important factors on soil erosion and sediment yield were evaluated. Numerical values were assigned to them in terms of intensity and weakness of each factor. Using the sum of those values different factors, the amount of sediment yield in basin was calculated as Qs= 0.253e0.036R and finally the map for each of the 9 factors were prepared in Arc GIS environment. According to identifying sub- basins with high sediment yield, V2 and V3 sub- basins deposit and this basin shall be among first priority for soil protection planning.
R Kohansal; M Ghorbani; S.M Pourmafi; M Khalatbari Jafari; J Omrani
Abstract
The Forumad ophiolite pillow lavas crop out at west of Sabzevar and at the periphery of north central Iran microcontinent. These lavas include Upper Cretaceous pelagic limestone with microfossils and are classified in two Late Turonian- Santonian and Coniacian- Late Campanian groups. These basaltic ...
Read More
The Forumad ophiolite pillow lavas crop out at west of Sabzevar and at the periphery of north central Iran microcontinent. These lavas include Upper Cretaceous pelagic limestone with microfossils and are classified in two Late Turonian- Santonian and Coniacian- Late Campanian groups. These basaltic pillow lavas have tubular and flattened forms, with external (vitrified), medial (variolite) and internal (intergranuler) parts. Each part has its own texture with mineral composition of clinopyroxene ± plagioclase ± olivine. The medial part is characterized by formation of skeletal crystals of olivine and lesser extend of plagioclase, indicating high nucleation rate. The nature of Late Turonian- Santonian lavas is tholeiitic and Coniacian- Late Campanian lavas are tholeiitic and calc-alkaline. Despite of enrichment in LILE, relative depletion of HFSE, different enrichment in LREE and various linear trends of HREE which suggest the formation of pillow lavas in the arc environment and the heterogeneous mantle with varying degrees of partial melting, but low ratios of Th/ Yb, La/ Nb, Ce/ Nb and Ce/ Th indicate that they are more inclined to intermediate between IAB and MORB environments. Unlike Late Turonian – Santonian lavas, high ratios of La/Yb, Nb/ Yb in Late Coniacian – Late Campanian lavas represent mantle fertility and decrease of Nb/ Ta ratios as well as relative increase of Th exhibit the effect of partial melting of subducted slab in genesis of these lavas. The depth of partial melting was 40 to 70 km in the spinel lherzolite stability zone. It seems that the formation of Forumad ophiolitic pillow lavas is accrued in a marginal basin to a back arc basin of a supra-subduction zone.
Akbar Jabbari; Asghar Dolati; Alireza Shahidi; Amin Behrooz
Abstract
Abstract: The Alborz Mountain range is formed by collision between the Central Iran and Eurasia plates, since Late Triassic. Facieses studies on the Alborz and Central Iran indicate sedimentation in shelf and epicontinental shelf in passive margin of Gondwana during Paleozoic Era. This study represents ...
Read More
Abstract: The Alborz Mountain range is formed by collision between the Central Iran and Eurasia plates, since Late Triassic. Facieses studies on the Alborz and Central Iran indicate sedimentation in shelf and epicontinental shelf in passive margin of Gondwana during Paleozoic Era. This study represents direction and paleostress analysis of the Central Alborz based on geometry and kinematics of faults; i.e. strike, dip, slicken line orientation and movement directions for Carboniferous and Permian Periods. Since many tectonic events occur after the Paleozoic Era in the Alborz Mountain range so just growth faults, active during sedimentation, which were not reactivated by later events were used for paleostress analysis. In total 15 stations, including 148 fault data are measured along the Tehran-Chalus road from Carboniferous and Permian outcrops. The data were rotated to the first position based on fold axes, when the layers were horizontal. FSA software (Fault Slip Analysis) was used to calculate orientations of principal stress directions. Primary results indicate a proximately North-South extension in Carboniferous and Permian Periods. Iran and adjacent area, rotated along vertical axis during its movements from Gondwana, in South, to Eurasia, in north, that based on the plate rotation the extension direction for Permian and Carboniferous Periods are NE-SW and ENE-WSW, respectively.
A. Kakouei; M. Masihi; M. Shirani
Abstract
Determination of different facies is one of the important and basic tasks of geological engineering characterization of reservoir rocks from well logs and core data. Our objective is to identify and determine different facies of the South Pars Field using RBF and PNN neural networks in order to perform ...
Read More
Determination of different facies is one of the important and basic tasks of geological engineering characterization of reservoir rocks from well logs and core data. Our objective is to identify and determine different facies of the South Pars Field using RBF and PNN neural networks in order to perform static and dynamic simulation. These networks are utilized to identify facies of the South Pars Field for the first time in Iran. In this study, we use different parameters of mentioned networks such as ‘spread’ and ‘goal numbers’ to improve networks operation. In this regards, the optimum values of these two parameters were 0.01-10 and 0.02-0.04 respectively. The results show that the RBF and PNN neural networks are robust means to determine and model the facies of the South Pars Field in Iran.
Economic Geology
shirin fatahi; Ahmad Jahangiri; Farhad Maleckqasemi; seyedhasan tabatabaei
Abstract
Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration ...
Read More
Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration such as Silicic, phyllic, intermediate argillic, advanced argillic and dolomitization. It seems that Arsenic mineralization has occurred in two main step: 1) Pyrite± Chalcopyrite± Arsenopyrite that are consistent with phyllic zone. Fluide responsible mineralization have high temperature (nearly 250 centigrade degree) and fs2 between 10-15 to 10-20 and 2) Pyrite± Native arsenic± Realgar± Orpiment± Galena± Stibnite wich are consist with intermediate argillic and advanced argillic zones. Hydrothermal fluid in this stage has lower temperature (nearly between 180 to 210 centigrade degree) with fs2 between 10-7.8 to 10-13. These assemblage are associated with hematite, diaspore, kaolinite, alunite and arsenolite. Average of arsenic grade in phylilc zone is 655 ppm and in argillic zone is 11930 ppm. Mass change calculation indicate enrichment in many metals such as As, Sb, Hg, Ag and Au. According to geochemical studies, As, Hg and Sb are pathfinder for probebly Porphyry copper mineralization and gold in study area.
