Editor-in-Chief Lecture
Volume 27, Issue 107 , June 2018, Pages 1-1
Reviewers
Volume 27, Issue 107 , June 2018, Pages 2-2
Original Research Paper
Economic Geology
Hadi Mohammaddoost; Majid Ghaderi; Jamshid Hassanzadeh
Abstract
Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and ...
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Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and Iju deposits and Serenu, God-e-Kolvari and Kader prospects is from -1.4 to +2.5 (average +0.31), -1.3 to +1.1 (average +0.07), +0.1 to +2.4 (average +0.87), -1.5 to +0.2 (average -0.1) and -4.1 to +1 (average -1.04), respectively. These results suggest a magmatic source for sulfur. Also, limited range of isotopic variations and analogous isotopic composition for the three types of veinlets reveals that with evolution of the hydrothermal system, no significant changes occurred in the primary and relatively homogenous source of sulfur. Comparison between the data for the Meiduk cluster with available data from other deposits in middle and southern parts of the Kerman belt suggested that in porphyry systems of the northwestern, and to some extent southern parts, of the Kerman Cenozoic magmatic arc, sulfur was provided by a mafic magma originated from metasomatized subcontinental lithospheric mantle (SCLM) which was affected by assimilation with continental crust; while in the southern parts, processes related to subduction and fluids from seawater and associated sediments had a major role in their sulfur isotope composition.
Original Research Paper
M. Arjomandi; A. Saremi; A. P. Sarraf; H. Sedghi; M. Roustaei
Abstract
Groundwater modeling, land subsidence hazards and proper management of groundwater resources of the alluvial aquifer in the district 19 of Tehran, south of Tehran Plain need precise estimation of aquifer hydraulic parameters. Besides, traditional techniques and usual graphical methods have been approximate, ...
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Groundwater modeling, land subsidence hazards and proper management of groundwater resources of the alluvial aquifer in the district 19 of Tehran, south of Tehran Plain need precise estimation of aquifer hydraulic parameters. Besides, traditional techniques and usual graphical methods have been approximate, expensive and time-consuming. In this paper, ten sets of aquifer test data were selected; moreover, these data were recorded in a well located in district 19 of Tehran, southwest of Tehran Plain during five years (2008 to 2012). For solving the previous methods’ problems, three computer codes have been developed to optimize aquifer parameters using three optimization approaches on the other hand, two kinds of genetic algorithms and a multi-elitist particle swarm optimization (MEPSO) which avoid getting stuck in local optima and save time. The efficacy and efficiency of the developed codes have been examined using ten sets of aquifer test data of a confined aquifer, and then their results have been compared with the results obtained by the graphical approach using AquiferTest software. Based on the fitness function, i.e. sum of square errors, the MEPSO and the GAs in descending order are more reliable for estimating the parameters contrast with the graphical method. Furthermore, the sensitivity analysis of the parameters during the performance of the optimization approaches has authenticated that the results obtained are enough precise and reliable. Then an equation has been presented according to the amounts of hydraulic conductivity which have been obtained using MEPSO during the years and the amounts of land subsidence rates which have been obtained using geodetic measurement methods to predict the amounts of land subsidence rates through the time when the amount of hydraulic conductivity will reach to Ultimately, based on the equation, after 30 years the amount of hydraulic conductivity will reach to and the total amount of land subsidence will be 0.5213 m from 2008 to 2038 . Moreover, land subsidence rates’ data obtained from interferometry synthetic aperture radar (InSAR) have confirmed the accuracy of the equations.
Original Research Paper
Sh. Shahabi; H. Shafaii Moghadam; Gh. Ghorbani
Abstract
The Ghoshchi granitic rocks are located in at north of Uromiyeh city and are mainly composed of alkali-feldspar granites, granites and aplitic dykes. These samples belong to calc-alkaline to shoshonitic series and show Fe enrichment and are classified as A-type granites. Ghoshchi granites have high K2O+Na2O, ...
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The Ghoshchi granitic rocks are located in at north of Uromiyeh city and are mainly composed of alkali-feldspar granites, granites and aplitic dykes. These samples belong to calc-alkaline to shoshonitic series and show Fe enrichment and are classified as A-type granites. Ghoshchi granites have high K2O+Na2O, FeO/MgO, Gl/Al, Ce/Nb, Zr, Y/Nb, and low CaO, Ba, Sr and Eu and are A2-type granites. Geochemical and Sr-Nd isotopes evidences suggest that these rocks were generated by highly fractional crystallization of a parental magma (melts), was derived from an enriched mantle source, which have undergone contamination by crustal materials and formed in post-collisional extentional environments in a within-plate setting. The crystallization age of these rocks, according to biotite 40Ar-39Ar and Rb-Sr dating is 262±26 Ma and 256±20 Ma, as minimum age, respectively, and 320-330 Ma as crystallization age. Ghoshchi granites formed probably within extentional zones in at the late stages of Variscan tectonic events.
Z. latifi; F. Foroughi; M. Motamedalshariati; S. N. Raeisossadat
Abstract
Calcareous nannofossils of Nimbolook section in north west of Qayen, east of Iran have been investigated. The section is 164 m thick and consists of limestone, marlstone and shale. Seventy six nannofossil species belong to thirty genera from fifteen families were identified. Based on the identified calcareous ...
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Calcareous nannofossils of Nimbolook section in north west of Qayen, east of Iran have been investigated. The section is 164 m thick and consists of limestone, marlstone and shale. Seventy six nannofossil species belong to thirty genera from fifteen families were identified. Based on the identified calcareous nannofossils, a part of subzone CC7b and biozone CC8 and a part of biozone CC9 of Sissingh biozonation (1977) and a part of subzone NC7 and biozones NC8, NC9 and a part of biozone NC10 of Roth biozonation (1978) have been suggested for the Nimbolook section. Therefore, an age of late Aptian–Albian and early Cenomanian? is assigned to the deposits of this section.
S. Alipour; Kh. Mosavi-ovenlegi; E. Hosseini; Sh. Aslanpour; Z. Haseli
Abstract
The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 ...
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The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 were investigated. General geochemical composition of samples revealed a very heterogeneous variation of major oxides at NW, NE, SW and SE parts of the lake. MgO, CaO and Na2O show a high enrichment compared to UCC, PAA and NASC values. Main minerals of the bed sediments include halite, calcite, ankerite, quartz, orthoclase, augite, hornblende and chlorite. The overall geochemical composition of sediments, resemble ferruginous shale and graywacke sandstone. Weathering in the various parts of the bed sediments is relevant to general climatological characters in the region. Rb and Sr among trace elements show high anomaly in respect to UCC, PAAS and NASC, while Eu indicated high depletion, especially at SW corner of the lake. Geochemical comparisons indicate the major role of different rock units in forming bed sediments rather than sediments carried by entering rivers to the lake.
Original Research Paper
M. Ebrahimi; M. Rafiei
Abstract
Eocene pyroclastic-volcanic rocks, ranging in composition from basic to intermediate and acidic rocks, are widely exposed at north of Zavieh, southwest of Karaj. The pyroclastic-volcanic sequence is composed of basalt, trachy-basalt, basaltic trachy-andesite, andesite, trachy-andesite, trachydacite, ...
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Eocene pyroclastic-volcanic rocks, ranging in composition from basic to intermediate and acidic rocks, are widely exposed at north of Zavieh, southwest of Karaj. The pyroclastic-volcanic sequence is composed of basalt, trachy-basalt, basaltic trachy-andesite, andesite, trachy-andesite, trachydacite, dacite and rhyolite along with various pyroclastic rocks including ignimbrite, welded tuff, crystal tuff, lithic tuff, lithic crystal tuff, ash tuff and lapillistone. The pyroclastic-volcanic sequence contains large amount of ignimbrite. Common textures found in the studied volcanic rocks are porphyritic, glomeroporphyritic, cumulophyric, amygdaloidal and trachytic. Rock fragments and broken crystals are usually found in the pyroclastic rocks. Eutaxitic texture is commonly observed in the ignimbrite. Flow banding is seen in the study rhyolitic rocks. Meanwhile, columnar structure is commonly observed in the lava flows and ignimbrites. Pyroxene, amphibole, biotite, plagioclase and quartz are the major minerals in the volcanic sequence along with K-feldspar, opaque minerals and altered olivine as minor minerals. Calcite, chlorite, epidote and sericite are also present as accessory minerals. According to geochemical data the studied volcanic rocks are mainly calc-alkaline, however few samples plot in the alkaline and shoshonitic fields in some diagrams. Negative anomalies of Nb and Ta, Pb positive anomaly, large ion lithophile elements enrichment, rare earth elements enrichments and depletion in high field strength elements all indicate that the parent magma of the studied rocks has originated from a metasomatized asthenospheric mantel over the Benioff-Waddatti zone. Common existence of sieve texture in plagioclase crystals, corroded crystals of plagioclase and pyroxene and dark rim of Fe-Ti oxides around biotite and amphibole crystals all indicate that a disequilibrium condition existed during crystallization which is most probably due to magma mixing. However, assimilation, decompression and rapid ascend of magma may also produce such textures.
Original Research Paper
R. Samadi Moghadam; R. Nozaem; M. Dehbozorgi; M. Mohajjel
Abstract
Derenjal Mountains with NE-SW trend, is located in Central Iran, in northwest of Tabas block and in eastern block of Kalmard fault. In this region, the Paleozoic formations (Cambrian to Devonian) have been exposed and surrounded by Neogene and Quaternary deposits. Volcanic rocks of Cambrian limited to ...
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Derenjal Mountains with NE-SW trend, is located in Central Iran, in northwest of Tabas block and in eastern block of Kalmard fault. In this region, the Paleozoic formations (Cambrian to Devonian) have been exposed and surrounded by Neogene and Quaternary deposits. Volcanic rocks of Cambrian limited to Diabasic Rocks Dominated in Kalshaneh Formation and Middle Jurassic (?) lens-shape Andesite massive that covered uncomfortably with Cretaceous non metamorphosed limestone. Kalmard Fault as an old basement and active fault in Central Iran as Principal Displacement Zone (PDZ) and adjacent deformed Deranjal Mountains, have a complex deformation history with respect to rotation of the Compressional Incremental Kinematic Axis during Geological time scale since late Paleozoic to late Cenozoic. Rotation in Central Iran blocks, changing of the convergence direction of Afro-Arabian plate with respect to Iran and also structural interaction between the Central Iran blocks, during tectonic evolutions, imposed the rotation of the Incremental Kinematic Axis (P-T-B) directions with respect to Derenjal Mountains and Kalmard Fault. These process made progressively new structures and also made changes in old structures since post Devonian. In this study, based of Field observation and geometric - kinematic structural Analysis of the more the 150 fault data, the architecture of fault assemblage of Derenjal area demonstrate Synthetic faults (P, R), antithetic faults (X, R’), compression faults (C2) faults and folding in F1 Class in Derenjal Area. These structures represent that the Compressional Incremental Kinematic Axis trend has been changed in anticlockwise direction from perpendicular to parallel with respect to Kalmard Fault since post Devonian to Late Cenozoic and finally superimposition of the strike slip tectonics on the contraction tectonics.
Original Research Paper
N. Alidadi; A. Mahdavian
Abstract
When seismic waves pass through alluvial layers, the seismic wave amplitude increases significantly in some periods, which is known as site amplification. In this case, it can be analyzed with an analytical model of the surface response spectrum Estimates of the input response spectrum. This behavior ...
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When seismic waves pass through alluvial layers, the seismic wave amplitude increases significantly in some periods, which is known as site amplification. In this case, it can be analyzed with an analytical model of the surface response spectrum Estimates of the input response spectrum. This behavior is essential in assessing the seismic performance of the structures and vital arteries. In this paper, we investigate this effect on different layers of sand with different thicknesses for Urmia city, a metropolitan area in the North West of Iran and an earthquake prone region. 120 geotechnical boreholes were drilled in sandy layers of different thicknesses in the central and northern parts of the city. The analysis simulated artificial acceleration based on seismic hazard analysis results. By observing the spectral accelerations for different periods at the earth’s surface the spectral acceleration magnitudes of the seams were shown for different periods. Using a neural network and genetic algorithm, these coefficients were modelled. Using the evolutionary algorithm of gene expression programming, the mathematical relation was expressed in terms of sand layer thickness and different periods. However, the results obtained from the artificial neural network using the correlation coefficient and root mean square yielded more accurate results than the gene expression programming. In conclusion, the results show that by increasing the thickness of the sand layers, the amplification ratio also increases considerably for some periods. Using the modeling results, we can estimate the amplification of the sandy soils of Urmia city with different thicknesses for variables up to 4 seconds.
Original Research Paper
S. N. Haghighi Bardineh; R. Zarei Sahamieh; H. Zamanian; A. Ahmadi Khalaji
Abstract
The Takht iron deposit is located 120 km northeast of the Hamedan City in the Urumieh-Dokhtar magmatic belt. The Miocene Takht granodiorite intruded into the Cretaceous carbonates and resulted in Fe-skarn formation. Epigenetic mineralization in the Takht Deposit occurred predominantly as vein and lenticular ...
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The Takht iron deposit is located 120 km northeast of the Hamedan City in the Urumieh-Dokhtar magmatic belt. The Miocene Takht granodiorite intruded into the Cretaceous carbonates and resulted in Fe-skarn formation. Epigenetic mineralization in the Takht Deposit occurred predominantly as vein and lenticular ore bodies accompanied with argillic, carbonation, chloritization, epidotization and silicfication alterations and minerals including garnet, pyroxene, epidote, tremolite- actinolite, phlogopite, hornblende, quartz, calcite, magnetite, pyrite, specularite, chalcopyrite, hematite, limonite, goethite and malachite. Chemical composition indicates the presence of Si, Al, Ca, Mg, Ti and chalcophile elements such as Cu, Zn, As and Pb that originate from the coexistence of silicate and sulfide minerals with magnetite. The microthermometric results revealed homogenization temperatures (Th) from 153.2°C to 338.3°C and salinity from 0.827 wt.% NaCl eq. to 25.36 wt.% NaCl eq.. The δ18O (SMOW) values of magnetite were measured in the range of −0.46‰ to +2.31‰ and δ18O water is +8.1‰ to +10.9‰, respectively. These isotope values are similar to magmatic fluids that were also equilibrated with 18O enriched sources. The δ34S (V-CDT) values of pyrite show ranges of +7.3‰ to +12.5‰ and the original fluid δ34S H2S values were estimated ranging from +5.7‰ to +10.9‰. These positive δ34S values confirm that sulfur is provided by evaporate sulfates. During the retrograde stage of the Takht Skarn, re-mobilized metals accompanied with metal-bearing fluids (provided by intrusion) were mixed with sulfur-bearing descending meteoric waters and eventually, the mixing of the two fluids led to calcic Fe-skarn mineralization in Cretaceous carbonates.
Original Research Paper
M. Morsali; M. Nakhaie; M. Rezaie; H. R. Naseri; J. Hassanpour
Abstract
Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater ...
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Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater inflow into the tunnel. Groundwater inflow was estimated by means of empirical and analytical methods. Daily measurements of inflow rate show that there are some differences between the calculated and the observed inflow value. In this research, based on the comparison between the observed and calculated groundwater inflow, some relations have been derived for similar hydrogeological conditions. In many hydrogeological conditions, the analytical equations are supervised on empirical formula. According to this research, addition to permeability and water head; geological structure, Precipitation and bedding dip have a significant effect in water inflow into tunnels. Also, most of groundwater inflow along the Karaj tunnel is largely related to the main geological features, such as folds, faults, dykes and open fractures and inflow is correlated with precipitation.
Original Research Paper
H. Ghasemi; M. Rostami Hossuri; M. Sadeghian
Abstract
The Lower Jurassic basin of northern margin of central Iran structural zone and south of eastern Alborz in Semnan province, contains igneous rocks with basic composition, belonging to early stages of occurrence and development of an immature extensional back arc basin at this time. These basic igneous ...
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The Lower Jurassic basin of northern margin of central Iran structural zone and south of eastern Alborz in Semnan province, contains igneous rocks with basic composition, belonging to early stages of occurrence and development of an immature extensional back arc basin at this time. These basic igneous rocks cropped out in at the base of Shemshak Formation and its equivalent in central Iran Structural zone, in the form of extrusive (basaltic rocks) and intrusive (dike, sill and microgabbroic small stocks) rocks. Magma forming of these rocks have had calc – alkaline nature and was enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and also was depleted in heavy rare earth elements (HREE). The mentioned magmas was, originated from 5 to 30% partial melting of the spinel peridotitic (below the central Iran) and garnet lherzolithic (below the Eastern Alborz) mantle plumes in an immature extensional back arc basin tectonic setting due to oblique subduction of Nneothetyan oceanic lithosphere beneath the central Iran structural zone at late Triassic to middle Jurassic time, and were ascending to upper levels of continental crust by fault and fracture systems and emplaced in shallow sedimentary basins of these zones in different ways. This basin was formed in the behind of the upper Triassic – Lower Jurassic magmatic arc of central Iran and due to initiation of extensional movements in the continental crust of central Iran and Alborz.
Original Research Paper
N. Hadavandkhani; A. Sadeghi; M. H. Adabi; A. R. Tahmasbi
Abstract
The Pabdeh Formation with a thickness of 797.2 m. and 4 lithological units (purple shale (144.25 m.), lower limestone and marl (221.75 m.), limestone (73.5 m.) and upper limestone and marl (357.7 m.) is stretched at Chahardeh village stratigraphic section in Izeh zone.. Biostratigraphic studies led to ...
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The Pabdeh Formation with a thickness of 797.2 m. and 4 lithological units (purple shale (144.25 m.), lower limestone and marl (221.75 m.), limestone (73.5 m.) and upper limestone and marl (357.7 m.) is stretched at Chahardeh village stratigraphic section in Izeh zone.. Biostratigraphic studies led to recognition of 30 genera and 150 species of planktonic foraminifera based on which 23 biozones were identified in Tethys realm. These biozones are well correlated with biozones of Tethys region. Based on the indicated biozones and fossil contents, the age of the Pabdeh Formation is Middle Paleocene (Selandian) - Late Oligocene (Chattian). In this study, Paleocene- Eocene boundary is located in Purple shale unit and Eocene- Oligocene boundary is placed in upper marl and limestone unit.
Original Research Paper
E. Keshtkar; M. Ghorbani; J. Omrani
Abstract
A gabbro to monzonite sill is injected into the Karaj tuffs at the north of Parachan village, North of Karaj.. The main minerals of these rocks are plagioclase, pyroxene, K feldspar, olivine and biotite. Clinopyroxene mineral chemistry studies carried out on the intrusive bodies, indicate two types of ...
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A gabbro to monzonite sill is injected into the Karaj tuffs at the north of Parachan village, North of Karaj.. The main minerals of these rocks are plagioclase, pyroxene, K feldspar, olivine and biotite. Clinopyroxene mineral chemistry studies carried out on the intrusive bodies, indicate two types of diopside and augite clinopyroxene composition. The chemical composition of the pyroxenes shows that these rocks have been crystallized in a subduction geological setting. The average crystallization temperature of clinopyroxenes is about 1120 to 1170 °C, and it seems that clinopyroxenes crystallized at lower temperature than orthopyroxenes. Plagioclase composition in these rocks is variable, changing from andesine to labradorite. K feldspars are in the orthoclase range and olivine are hyalosiderite. Biotite is one of the most prominent ferromagnesian minerals in the studied bodies. Compositionally, it is plotted between the fields of annite and siderophyllite. Most of these biotites are primary magmatic and some are plotted in the re-equilibrated filed. Petrological evidence represent that fractional crystallization from gabbro to monzonite had main role in genesis of these rocks. Enrichment in LILE) Ba, Rb and Th(and also depletion in HFSE (Nb and Ti) in Rare Earth Elements distribution pattern in spider diagrams, indicate features of subduction-related rocks. Also they are enriched in LREE rather than HREE, the characteristic which is usually observed in the rocks from subduction environments and active continental margins. Chemical and petrological studies, indicate role of fractional crystallization in the evolution of magma, although, minor amounts of assimilation and contamination of magma by crustal rocks occurred. This alkaline magma has been formed by low degree of partial melting of an enriched sub-continental lithospheric garnet-lherzolite mantle source.
Original Research Paper
A. Ghaderi; J. Taheri; A. Kerachian; A. Mousavinia
Abstract
Investigation of Silurian succession equivalent to the Niur Formation at the northwest of Robat-e-Qarebil (instantly south of Western Kopeh-Dagh), is led to introduction of lithostratigraphical units in details and identification of some Llandovery conodonts. The sampled interval in this stratigraphic ...
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Investigation of Silurian succession equivalent to the Niur Formation at the northwest of Robat-e-Qarebil (instantly south of Western Kopeh-Dagh), is led to introduction of lithostratigraphical units in details and identification of some Llandovery conodonts. The sampled interval in this stratigraphic section is composed of shale, fossiliferous limestone, sandstone, and dolomite with 295.5 meter thickness. With a marine volcanic rock unit at the base, this succession is conformably overlaid shales and sandstones attributed to the Ordovician system and overlain by quartzarenite and red shales of the Padeha Formation. Obtained conodonts from these sequences comprise different coniform, ramiform and pectiniform elements. Nineteen species of 10 genera belong to Aspelundia expansa Interval Zone which confirms uppermost Late Rhuddanian to Aeronian for the section. This age coincides with the ages which have already been given on the basis of brachiopods, cephalopods and palinomorphs for the same outcrops at the Western Kopeh-Dagh.
Original Research Paper
A. R. Najafzadeh
Abstract
The Rudan ultramafic complex with Paleozoic age is located in Southern Kerman province and is composed mainly of massive harzburgite, small to medium sized lenticular dunite and subordinate very thin olivine websterite dykes. Granular and protogranular are the main textures in dunites and harzburgites, ...
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The Rudan ultramafic complex with Paleozoic age is located in Southern Kerman province and is composed mainly of massive harzburgite, small to medium sized lenticular dunite and subordinate very thin olivine websterite dykes. Granular and protogranular are the main textures in dunites and harzburgites, and orthopyroxene, olivine and to a lesser extent clinopyroxene and chromian spinel were found in the harzburgites and dunites. The forsterite content of olivine is slightly higher in dunites (Fo92.5) than those in harzburgites (Fo91). Detailed electron microprobe study reveals intermediate Cr# (0.33-0.56), relatively high Mg# (0.59-0.75) and very low TiO2 content (averaging 0.01 wt %) for chromian spinels in Rudan peridotites. The Fe3+# is very low, (s in the peridotites are very low (average 25 ppb) and are highly depleted in PGE contents relative to chondrites. The PGE spidergrams in dunites are unfractionated, and the PdN/IrN ratios averages 1.02, whereas the harzburgites show slightly positive slopes PGE spidergrams, together with a small positive Ru, Pd and Au anomalies, and their PdN/IrN ratio averages 2.75. Moreover, the PGE chondrite and primitive mantle normalized patterns of the harzburgites are relatively flat which are comparable to the depleted mantle peridotites indicating relatively high degree of partial melting (about 17-22%) of the mantle source. The mineral chemistry data and the noble metal geochemistry indicates that the harzburgites of the Rudan ultramafic complex are residual and dunites are replaced and tectonically have been generated in a fore-arc mantle region above a supra-subduction zone setting.
Original Research Paper
H. Mahdizadeh; Y. Djamour
Abstract
Today, with the use of Global Positioning System (GPS), it is possible to determine the geodetic height (relative to a Reference Ellipsoid) in easy mode with less time and cost. Despite of some advantages for leveling with GPS (GPS/Levelling) relative to traditional leveling, there is an important limitation ...
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Today, with the use of Global Positioning System (GPS), it is possible to determine the geodetic height (relative to a Reference Ellipsoid) in easy mode with less time and cost. Despite of some advantages for leveling with GPS (GPS/Levelling) relative to traditional leveling, there is an important limitation which indicates the difference between Ellipsoid (as the reference datum for geodetic height) and Geoid (as the reference datum for orthometric height) named geoidal height. In order to achieve maximum accuracy in height component and then evaluating the quality results, different aspects of GPS/Levelling are considered in this study. In order to study the Feasibility of replacing precise levelling with GPS in Iran, a part of 55 km physical geodesy and geodynamic network in Azerbaijan region as well as the dense geodetic multipurpose network in Qeshm island were used. Based on different distances between each couple of points, this information, consisting of Orthometric and Geodetic heights for each point, is classified in 5 groups. The last Geoid model of Iran (IRGeoid10) with an absolute average accuracy of ±26 cm and a relative average accuracy of ±2.8 ppm are used for geoidal height. Obtained results show the accuracy of leveling height difference with GPS would be reduced by increasing the length of baseline. Index K as a criterion for determining level degree was calculated. This index shows that levelling with GPS in Iran could provide a precision of 4th degree leveling which can serve many engineering applications.
Original Research Paper
Geophysics
Mohammad Reza Ebrahimi; Mohammad Tatar
Abstract
Impoundment of a reservoir and changes in the lake levels can trigger / induce the seismicity. In this research, the strength changes are modeled across the Golestan fault, due to loading effect of Gotvand-e Olya reservoir which is located in the Zagros Mountain of SW Iran. The formulas based on 3D Boussinesq ...
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Impoundment of a reservoir and changes in the lake levels can trigger / induce the seismicity. In this research, the strength changes are modeled across the Golestan fault, due to loading effect of Gotvand-e Olya reservoir which is located in the Zagros Mountain of SW Iran. The formulas based on 3D Boussinesq solutions were used to calculate normal and shear stresses on a given fault plane. Geometry and mechanism of the Golestan fault were precisely determined using local earthquakes recorded by a local seismological network. For a better analysis, we did the calculations in three different dips of 55, 60 and 65 degrees for the Golestan fault. Since the lake is located on the hanging wall of the Golestan fault, it is expected that loading effect of the reservoir causes delay on occurrence of earthquakes and make the fault more stable. Analysis of induced stresses confirms this too, the results in all dips in most parts of the fault from 7 km to 20 km depth, which are in closer distance to the reservoir, indicate on stabilization. Only in a small part of the fault, located at shallow depths between 5 and 7 km, the destabilizing effect is observed. The calculated strengths, which leads to destabilizing the Golestan fault ranges between -0.243 bars and 0. The observed seismicity in vicinity of the Golestan fault for before and after the impoundment confirms the the results of stress modelling in different parts of the fault.
Original Research Paper
M. SoltaniNezhad; H. Ahmadi Pour; A. Moradian; B. Zaboli Sarvtamin
Abstract
The Hadji-Abad ultramafic complex is located at the north of Hormozgan province and represents a part of Orzuieh-Dowlat Abad colouredmelange in the northern edge of Zagros thrust. The complex contains harzburgites, lherzolites, dunites and chromitites. Harzburgite is the dominant rock type. Evidence ...
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The Hadji-Abad ultramafic complex is located at the north of Hormozgan province and represents a part of Orzuieh-Dowlat Abad colouredmelange in the northern edge of Zagros thrust. The complex contains harzburgites, lherzolites, dunites and chromitites. Harzburgite is the dominant rock type. Evidence such as lobateboundaries, elongation of chromianspinels and pyroxenes, evidence for incongruent melting of orthopyroxenes and exsolution lamellae of clinopyroxenes show that the studied peridotites, experienced high temperature deformation in the upper mantle, and then emplaced in the crust. Different amounts and various shapes of chromite grains occur in all of the studied lithological units. In the harzburgites and lherzolites, disseminated brown chromites are seen as either euhedral isolated crystals or anhedral interstitial ones which crystallized between the other minerals. In the dunites, chromites appear as disseminated black euhedral and subhedral crystal grains which formed within or at the boundaries of olivine grains. In the high grade chromitites, the coarse black euhedralchromites show smooth and triple junction boundaries with cumulative textures, while in the low grade types, disseminated euhedralchromites set in a silicate matrix. Chemical analysis of disseminated chromites in the studied rocks show that maximum amounts of Cr# belong to those exist in the high grade chromitites (80-84) and the minimum are for those in the lherzolites (45-52). Tectonic discrimination diagrams reveal that chemical compositions of chrome spinels from the harzburgites and lherzolites are similar to those exist in the suprasubduction zone mantle peridotites. The host rocks as a part of ophiolites in this environment, suffered 15 to 20% partial melting. Disseminated chrome spinels from the dunite and also the chromitites have been crystallized from boninitic type melts in the same tectonic setting. These evidence show that probably, Hadji-Abad peridotites and their host ophiolitemelange belong to suprasubduction zone upper mantle and the evolutions related to this environment such as melt-peridotite reaction and partial melting have been recorded in their mineral chemistry and textures.
Original Research Paper
S. Dashti Chandanagh; M. R. Sheikholeslami; J. Taheri
Abstract
This study was conducted to determine the deformation pattern of the Mashhad metamorphic rocks which results from the convergence between Turan and Central Iran plates and closure of Paleotethys Ocean during Early Cimmerian event. The results of 2D and 3D strain analysis show that the maximum deformation ...
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This study was conducted to determine the deformation pattern of the Mashhad metamorphic rocks which results from the convergence between Turan and Central Iran plates and closure of Paleotethys Ocean during Early Cimmerian event. The results of 2D and 3D strain analysis show that the maximum deformation is concentrated in the central part of the study area and most strain shape parameters (K) obtained from oriented samples are located within the flattening part of the Flinn diagram. Strain intensity parameter in most cases is less than 0.5 and a maximum strain occurred in the central part which is reduced towards the margins. This is the most characteristic of the typical shear zones in which, the maximum strain is concentrated on the central part. Calculated vorticity numbers is ranged between 0.2 to 1 indicating the presence of both pure shear and simple shear during a transpressional regional deformation.
Original Research Paper
A. Yavari; M. Ghavidel syooki; M. R. Majidifard; S. H. Vaziri
Abstract
The Kazhdumi Formation is well exposed and accessible in Tang-e Maghar, northwest of Behbahan city, Zagros basin. In this area, this formation has a thicknees of 344 m and it mainly consists of alternation of black - gray shale with medium – thin-bedded cream – gray argillaceous limestone. ...
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The Kazhdumi Formation is well exposed and accessible in Tang-e Maghar, northwest of Behbahan city, Zagros basin. In this area, this formation has a thicknees of 344 m and it mainly consists of alternation of black - gray shale with medium – thin-bedded cream – gray argillaceous limestone. The lower contact of the Kazhdumi Formation is disconformable with Daryan Formation and conformable with the Sarvack Formation at the top. A total of 220 ammonite bearing surface samples were collected including the uppermost part of the Daryan Formation (5m) and the whole thickness of the Kazhdumi Formation (344m). This investigation resulted in 21 species (15 genera) which belong to six families. The encountered ammonite species of the upper part of the Daryan Formation and the whole Kazhdumi Formation consist of Douvilleiceras sp., Douvilleiceras cf. mammillatum, Epicheloniceras subnodosocostum– buxtorfi, Hypacanithoplites cf. elegnas, Acanthohoplites cf. aschiltaensis, Nolaniceras nolani, Parahoplites cf. melchioris, Venezoliceras sp., Venezoliceras cf. venezolanum, Mirapelia cf. buarquianum, Mirapelia sp., Oxytropidoceras carbonarium, Oxytropidoceras cf. roissyanum, Hysteroceras cf. orbignyi, Hysteroceras sp., Tonohamites cf. aequicingulatus, Mortoniceras sp., Mortoniceras aff. inflatum, Dufrenoyia sp., Hemiptychoceras cf. gaultinum and Scaphites sp.Amongst these ammonite species, Scaphites sp. and Hemiptychoceras gaultinum are recorded for the first time and the remainder has previously been recorded from this rock unit in the Zagros basin. Likewise, based on stratigraphic potential of the encountered ammonite species the lower Aptian is suggested for the upper part of the Daryan Formation and upper Aptian –upper Albian for the Kazhdumi Formation.Therefore, a hiatus is present between the Daryan and Kazhdumi formations, encompassing the middle Aptian.
Original Research Paper
B. Sameti; A. Zia Zarif; M. R. Jafari; A. Darvishzadeh
Abstract
The study area is located in Farash 1:50000 sheet in Kerman province, at a distance of about 50 kilometers from the Jiroft-Darb Behesht road in the Jebalbarez zone. The study area is located in Bam 1:250000 sheet in the Sanandaj-Sirjan structural zone. Rock units include granite, granodiorite and volcano-sedimentary ...
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The study area is located in Farash 1:50000 sheet in Kerman province, at a distance of about 50 kilometers from the Jiroft-Darb Behesht road in the Jebalbarez zone. The study area is located in Bam 1:250000 sheet in the Sanandaj-Sirjan structural zone. Rock units include granite, granodiorite and volcano-sedimentary rocks combined with tuff, nummulite limestone, conglomerate and agglomerate. Due to intrusion of igneous rocks in the southern part of limestone and tuff, iron skarn mineralization is occurred. Using processing and interpretation of 1030 data ground magnetic survey with lines space of 25 meters and preparing maps of magnetic intensity and using data layers such as geological and tectonic maps, areas with potential mineralization of iron ore were introduced. After field control, it was cleared that the main outcrops of iron ore are concentrated in the central parts of the South East. The main host iron ore are skarn and granite in the middle part of the area. Trend of mineralization is NW-SE and main minerals of iron are magnetite and hematite. Iron mineralization are also occurred in zones of argillic and propylitic alteration.
Original Research Paper
E. Asadi Mehmandosti; Sh. Alivand; H. Ghalavand; A. R. Rostami
Abstract
Nuclear magnetic resonance (NMR) is a test method that has had basic influence on the accuracy of reservoir parameters prediction. In this study, petrophysical properties of the Ilam Formation in one oil field of the Abadan plain were investigated by Nuclear magnetic resonance method, and core analysis ...
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Nuclear magnetic resonance (NMR) is a test method that has had basic influence on the accuracy of reservoir parameters prediction. In this study, petrophysical properties of the Ilam Formation in one oil field of the Abadan plain were investigated by Nuclear magnetic resonance method, and core analysis and thin sections data were used to validate the test results for the first time. The Nuclear magnetic resonance method was used to determine reservoir parameters such as porosity, permeability and rebuilding of capillary pressure curve in studied oil field. Correlation between petrophysical results of Nuclear magnetic resonance method, core data and microscopic thin sections indicates effectiveness of this method in determining the reservoir parameters. In addition, evaluation of the Ilam Formation carbonate with NMR method indicates that the studied reservoir at depths of 2890 to 2846 m has suitable reservoir quality in terms of hydrocarbon storages in studied oil field in Abadan plain.
Original Research Paper
S. M. Tabatabaei Manesh; F. Javadi; F. S Zohouri2
Abstract
The Nabar skarn is located about 35 km southwest of Kashan and within the Urumieh- Dokhtar magmatic belt and is formed along the contact between limestone of Qom formation with a probably middle to upper Miocene intermediate and basic intrusion body. The main minerals forming this skarn are garnet, ...
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The Nabar skarn is located about 35 km southwest of Kashan and within the Urumieh- Dokhtar magmatic belt and is formed along the contact between limestone of Qom formation with a probably middle to upper Miocene intermediate and basic intrusion body. The main minerals forming this skarn are garnet, clinopyroxene, epidote and accessory minerals are vesuvianite, chlorite, tremolite- actinolite, sphene, quartz and calcite. Ore minerals are pyrrhotite, pyrite with smaller amounts of chalcopyrite, sphalerite and magnetite. According to the presence of magnesium minerals like diopside and calcium minerals such as garnet, vasuvianite and epidote the type of host rock is probably calcite-dolomite. Skarn formation and mineralization in this region was occurred during three development stages. Presence of high temperature anhydrous minerals such as grossular and diopside specifies the formation of the first Stage in these rocks. Stage 2 is associated with the formation of andradite and sphene. Stage 3 is specified by replacement of anhydrous minerals at temperatures below 470 ° C by hydrous minerals such as tremolite-actinolite, epidote, chlorite and vesuvianite.
Original Research Paper
F. Vaez-Javadi
Abstract
Hojedk Formation spreads well through the Tabas Block. Diverse and moderately preserved palynofloras occur in the Middle Jurassic sediments of the formation in south Kouchekali, southwest of Tabas, central-east Iran. The present investigation of the Hojedk Formation has revealed a diverse assemblage ...
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Hojedk Formation spreads well through the Tabas Block. Diverse and moderately preserved palynofloras occur in the Middle Jurassic sediments of the formation in south Kouchekali, southwest of Tabas, central-east Iran. The present investigation of the Hojedk Formation has revealed a diverse assemblage of dinoflagellate cysts in which 12 species allocated to 5 genera. Two acritachs were also recognized, permitting establishment of Nannoceratopsis triceras-Pareodinia ceratophora Assemblage zone, and Nannoceratopsis gracilis Total Rane Subzone in the upper part, lower and upper boundaries have been identified by the first and last observed occurrence (LOO) of these index species. These biozones are comparable to the other palynozones in Iran and elsewhere especially in the northern hemisphere (Greenland, Norway, Scotland, England, and Poland). Occurrence of various species of Nannoceratopsis is concluded that this locality was located at the south palaeocoastal line of the Tabas Block during the Aalenian-Bajocian.
Original Research Paper
Z. Alishavandi; H. Rahimpour-Bonab; A. Kadkhodaei; M. Arian
Abstract
The Sarvak Formation deposited in the North to Northeastern margin of the Arabian Platform during the Mid-Cretaceous (Albian-Turonian), and is extensively encountered in the Folded Zagros of southwestern Iran. It is the most important reservoir unit after Asmari Formation in Iran. Petrography of microscopic ...
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The Sarvak Formation deposited in the North to Northeastern margin of the Arabian Platform during the Mid-Cretaceous (Albian-Turonian), and is extensively encountered in the Folded Zagros of southwestern Iran. It is the most important reservoir unit after Asmari Formation in Iran. Petrography of microscopic thin sections in studied wells led to determination of nine microfacies that deposited in 3 sub-environments; restricted lagoon, lagoon-open marine and shoal in an interior part of carbonate ramp. Petrographic studies revealed that since deposition, the Sarvak Formation experienced several diagenetic realms including marine, meteoric, burial and telogenetic diagenetic environments. Location of the studied wells shows that the relative depth of the Sarvak Formation ramp decreases from the east to the west. Also, the results show that the Sarvak reservoir quality affected by various diagenetic processes such as micritization, dissolution, dolomitization, cementation, stilolitization and fracturing. These diagenetic successions are mainly restricted to the upper and lower parts of the Cenomanian-Turonian disconformity. Meteoric water infiltration below this disconform boundary and related karstification led to development of moldic and vuggy porosity a long with reservoir quality increase. Based on the sequence stratigraphic study, three third-order sequences were recognized in the middle Cenomanian to middle Turonian part of the formation. The results of this research show that the reservoir quality distribution in this unit is primarily controlled by depositional facies so that the rudist microfacies (grainstone, floatstones and rudstones) have the best primary reservoir qualities though, it has also been drastically improved by dissolution in paleoexposure surface
Original Research Paper
H. Peernajmodin; E. Rastad; A. Rajabi
Abstract
The Kouh-Kolangeh carbonate-hosted Zn-Pb-Ba deposit is hosted by Lower Cretaceous detrital-carbonate sequence in the central part of the Malayer-Isfahan metallogenic belt (MEMB) and has been formed within an extensional basin. Ore mineralization occurred as concordant with layering in the upper part ...
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The Kouh-Kolangeh carbonate-hosted Zn-Pb-Ba deposit is hosted by Lower Cretaceous detrital-carbonate sequence in the central part of the Malayer-Isfahan metallogenic belt (MEMB) and has been formed within an extensional basin. Ore mineralization occurred as concordant with layering in the upper part of non- argillic massive orbitolina gray limestone (Kl) and at the boundary of shale- marl with intercalated thin bedded limestone unit (Ks) with Aptian age. Sulfide minerals include sphalerite, galena and pyrite. Barite is the most abundant non-sulfide mineral associated with quartz, calcite and dolomite. Ore textures and structures include breccia, replacement, vein-veinlets, massive barite and laminated ore. Silicification and carbonatation (calcification- dolomitization) are the main wall-rock alterations. Based on fluid inclusion studies, fluid inclusions can be divided into two types: (I) two-phase fluid inclusions (T1) with amoebic and irregular shapes and average homogenization temperature of (T1) 206.8°C and the average salinity of 8.3 wt% NaCl. (II) CO2-rich three-phase fluid inclusions (LCO2-LH2O-VCO2) (T II) with spherical shapes and average total homogenization temperature of (T1) 234.8°C and the average salinity of 7.17 wt% NaCl. According to evidence such as tectonic setting, type of host rock, layered geometry of deposit, ore textures and structures, homogenization temperature, average salinity and presence of massive barite, the Kouh Kolangeh deposit can be considered as an Irish-type Zn- Pb deposit.
