Stratigraphy and Palaeontology
Ali Jalali; Hamed Yarahmadzahi; Mehran Arian; Abdollah Saidi; Seyed Mohsen Aleali
Abstract
The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the ...
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The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the Moscovian deposits of the Abshani formation. The upper boundary of these deposits with the Tighe-Madanou formation is continuous. The assemblages of fusulinids in the Shishtou section such as Ruzhenzevites-Rauserites-Triticites are identified in the upper part of Gzhalian previously reported from equal deposits in Darvaz, Fergana, Southern Urals, Donetsk and Carnic of Alps, as well as, Central Iran, Central Alborz and Sanandaj-Sirjan zones. Also, different species of Sphaeroschwagerina, Pseudoschwagerina and Likharevites, which illustrate the Asselian age, represent the Carboniferous-Permian boundary in the studied section and allow for comparability with other structural-sedimentary zones of Iran, including Central Iran , Central Alborz (Doroud Group) and Sanandaj-Sirjan zone. This equivalence expresses the transgressive of sea level in different parts of Iran in the late Carboniferous and early Permian periods. In Shishto section 15 genera ,35 species and 2 subspecies of Fusulins have been identified, some of which are reported for the first time from Iran.
Geophysics
Marzie Shabani; Abolfazl Rezaei; Zohre Masoumi
Abstract
The water table in the Zanjanrood catchment has severely declined recently. Therefore, determination of the groundwater potential zoning map is of great importance for optimal management of water resources. Here, we used seven effective criteria including lithology, slope, drainage, lineament, rainfall, ...
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The water table in the Zanjanrood catchment has severely declined recently. Therefore, determination of the groundwater potential zoning map is of great importance for optimal management of water resources. Here, we used seven effective criteria including lithology, slope, drainage, lineament, rainfall, spring density and landuse to asses groundwater potential. The analytical hierarchical analysis process was used for weighting the criteria. Overlay analysis was implemented using TOPSIS model to prepare the groundwater potential map in four categories of priority including very-good, good, low and poor. In general, the very-good category corresponds with the first priority while the lowest potential of groundwater match with the fourth priority. The high-discharged production wells and the geoelectrical investigations (resistivity and induced polarization) were applied to verify the model. The spatial distribution of the high-discharge production wells has completely coincided with both the very-good and good priorities in the area. The results of resistivity and IP models also are in good agreement with those from the TOPSIS model. Overall, the results suggest there is no rich aquifer in mountains of the Zanjanrood catchment. Furthermore, the most important aquifer in the Zanjanrood catchment is located around the Zanjanrood River where a severe water table decline has occurred.
Stratigraphy and Palaeontology
maryam naderiyan; elahe zarei; khadijeh Mohammad-khani
Abstract
The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar ...
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The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar formation. In order to study paleoenviroment of the Dalichai Formation the authors examined many different factors including Microfacies and palynological data (abundance and diversity of Dinocyst, proximate to chorat Dinocyst, palynofacies analysis and "selective preservation of organic matter"). A high percentage of brown wood and sporomorphs and the dominance of cavate and proximate dinocysts such as Nannoceratopsis gracilis, and pareodinia ceratophora and fluorescent amorphous organic matter, as well as Miliolid benthic foraminifera are evidence of suboxic to anoxic condition, which favored accumulation and preservation of organic matter in open marine lagoon, in the lower part of Dalichai Formation. A decrease in the brown wood and abundance and species richness of marine palynomorph (mainly chorate dinocysts) reflects more offshore settings in the upper part of Dalichai Formation. On the other hand, Appearance and increase of planktonic foraminifera and Radiolar and posidonia indicate development of strong marine transgression and deposition in an open marine environment.
Stratigraphy and Palaeontology
Mir Amir Salahi; Abbas Ghaderi; Alireza Ashouri; Ali asghar siabghodsi
Abstract
To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based ...
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To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based on this fauna, Pycnodonte-Oestra community in the Chehelkaman Formation uppermost parts represents the late Paleocene age and the first occurrence of Flemingostrea hemiglobosa at the base of the Khangiran Formation confirms the beginning of Eocene epoch. Association of different species and subspecies of Turkostrea in the Khangiran Formation demonstrates the middle part of early Eocene and Sokolowia community near the top of the Khangiran Formation shows the Lotetian-Bartonin ages. These features are in full compliance with the bivalve communities recorded from the other parts of Central Asia such as Amu-Darya, Farghana, Afghan - Tajik and Trim basin of China. It illustrates the same geological history of the mentioned areas during Paleogene, indicates the occurrence of different types of molluscan taxa in the Kopet-Dagh basin is the same as parallel horizons and equivalent time units throughout the extensive Central Asian region.
Petrology
manijeh Asadpour; Soraya Heuss
Abstract
Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon ...
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Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon grains show 303.4 ± 2.2 Ma, indicating late Carboniferous - early Permian magma activity. The presence of older cores in some of zircon grains with age between 400 to 600 Ma, indicate presence of older rocks in the study area. The whole-rock isotopic analysis show negative initial Nd (t) = -1.3 with TDM = 1.61. These data provide evidence for partial melting of crust (with Neoproterozoic- Cambrian age) in early Permian. The 87Sr/86Sr = 0.752348 and εNd = -1.4 of whole rock and Th/U (>0.5) values in zircons show the involvement of more crustal and less mantle components, during the opening of Neo-Tethys Ocean. Due to the same mineralogical and geochemical composition and homogeneity with Qushchi granite, it is inferred that these patches are genetically related to Qushchi granite and are A type granite.
Tectonics
Mohamad Reza Sajadian; Manouchehr Ghorashi; Elahe Javadi Mosavi; Mohsen Pourkermani; Mehran Arian
Volume 28, Issue 110 , December 2018, , Pages 299-306
Abstract
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics. ...
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Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics. This is particularly valuable in west-central Alborz where relatively little work on active tectonics based on this method was done, so this method is new and useful. Based upon values of the stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), index of mountain front sinuosity (Smf) and transverse topographic symmetry factor (T), we used an overall index (Iat) that is a combination of the other indices. The low class of Iat are mainly in the sub-basins no; 6, 10,13,14,21,22,23,24,28 and the rest of the study area has moderate tectonic activities in the other sub-basins. Our results show that he moderate value has located along faulted area, which shows 2 class of relative tectonic activity.
Stratigraphy and Palaeontology
Abdolvahab Kazemi; Nasrollah Abbassi
Abstract
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints ...
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Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints of wetland small bird (Aviadactyla media, Gruipeda dominguensis), artiodactyls (Lamaichnum alfi, Lamaichnum isp., Pecoripeda satyri, Pecoripeda isp.), canids (Canipeda isp.) and large reptiles (Hatcherichnus sanjuanensis). Frequency of artiodactyl imprints are more than the other footprints. These footprints proof the living of camels and crocodiles in the Zagros basin for the first time. The ichnotaxa diversity of the footprints in the studied section is more than the other reports of Agha Jari Formation in Iran and its stratigraphic equivalent in the adjacent countries.
Sedimentology
Sedigheh Amjadi; Hamid Alizade Lahijani; Mohamad Hosein Mahmudy Gharaie; Razieh Lak; Nick Marriner
Abstract
AbstractAlthough the second deadliest tsunami in the Indian oceans was triggered in the Makran zone, our knowledge in regard to the number of tsunami events through the Holocene is negligible. In this study the sedimentary environment palaeo-tsunami have reconstructed and identified by Gulf of Oman deep ...
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AbstractAlthough the second deadliest tsunami in the Indian oceans was triggered in the Makran zone, our knowledge in regard to the number of tsunami events through the Holocene is negligible. In this study the sedimentary environment palaeo-tsunami have reconstructed and identified by Gulf of Oman deep sea cores. Sedimentation trends and effective factors on seabed sediments transportation by tsunami events were identified based on sedimentological parameters, foraminifera shells identification, magnetite susceptibility changes and palaeo-ocean currents reconstruction. The results of this study demonstrated that evidence of sea bed sediments transportation due to the strong earthquake in the Gulf of Oman were different through time and location. The palaeoenvironmental studies and historical tsunami events suggested at least five considerable submarine landslides through last 2500 cal. yr BP. The number of the events have dramatically increased during last thousand years. Rendering to the results and historical data, almost seven strong earthquakes were happened in the studied area that their traces have illustrated in this study. According to the city expansion in the southeast coast of Iran and increases number of earthquake events in the Makran zone adoption management plans in order to decrease probably tsunami damages are required.
Exploration and Mining
Kamran Mostafaei; Mohammadnabi Kianpour; Mahyar Yousefi
Abstract
This article is devoted to introducing a novel application of the Gray Wolf Optimizer in one of the most challenging issues related to mineral exploration, anomaly separation from the background in stream sediment geochemical studies. The Alut geological sheet, located in the Sanandaj-Sirjan zone, which ...
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This article is devoted to introducing a novel application of the Gray Wolf Optimizer in one of the most challenging issues related to mineral exploration, anomaly separation from the background in stream sediment geochemical studies. The Alut geological sheet, located in the Sanandaj-Sirjan zone, which has special importance to gold prospecting, has been studied for the distribution of gold and arsenic that accompany each other as the paracenteses in such deposits. The cost function used in this algorithm has been provided according to previously well-explored deposits. While the GWO algorithm was able to divide the sheet into two classes of anomalous and non-anomalous areas, the fractal method identified four categories among distributions of gold and arsenic, which impose the responsibility of selecting anomalous areas on the scientists. Obviously, the GWO draws the areas as potential zones of prospecting that may be neglected by fractal strategy. The derived results show that 24.8ppm and 15.7ppb is anomaly threshold for arsenic and gold distribution respectively. The comparison of the results shows that the anomaly threshold obtained by the fractal methods and GWO algorithm for arsenic is almost the same, but the anomaly threshold for gold in the GWO algorithm method is optimal.
Exploration and Mining
zohreh boroumand; Hadi Abdollahi; Reza Shahbazi; Shabnam Asl Pashaki; MirSaleh MirMohamadi
Abstract
Microbial-leaching of nickel from two arsenide ores (low- and high-grade samples) was precisely investigated. The microbial leaching of nickeline was accomplished with the admixture of mesophilic cultures in shake flasks with pulp densities of 0.5, 1, and 5% as well as 0.5, 1, and 3% respectively. The ...
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Microbial-leaching of nickel from two arsenide ores (low- and high-grade samples) was precisely investigated. The microbial leaching of nickeline was accomplished with the admixture of mesophilic cultures in shake flasks with pulp densities of 0.5, 1, and 5% as well as 0.5, 1, and 3% respectively. The nickel content was over 99% dissolved by mesophilic bacteria of low-grade and high-grade samples after 10 and 28 days respectively. In addition, three heterotrophic bacteria isolated from iron mine wastewater and tailing were used for bio-leaching of low and high- grade nickeline bearing arsenic ores. Three bacteria strains were investigated for their ability to leach from nickeline samples in different pulp densities (0.5%, 0.8%, 1.1%, and 3%)., Glutamicbacter nicotiana was more effective than the other strains. The Glutamicbacter nicotiana extracted Ni 100%, for the low-grade sample and up to 70 for the high-grade sample, respectively. The catalytic effect and galvanic interaction of different additives on the dissolution of the samples were investigated. In the low-grade sample, all four additives in both low-grade samples showed a positive efficiency. In high-grade, three of the four additives (silver-pyrite and L-Cysteine) had a positive effect on the dissolution of nickel.
Stratigraphy and Palaeontology
Maryam Alavi; Abbas Sadeghi; Mohammad Hossein Adabi; Nasrin Hadavandkhani; Yadolah Ezampanah
Abstract
In order to study the biostratigraphy of the Gurpi Formation in the Fars area, a stratigraphic section is selected and sampled in the Sarbalesh anticline. The thickness of the Gurpi Formation in this section is 346.3 meters and its main lithology includes argillaceous limestone and shale. The lower boundary ...
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In order to study the biostratigraphy of the Gurpi Formation in the Fars area, a stratigraphic section is selected and sampled in the Sarbalesh anticline. The thickness of the Gurpi Formation in this section is 346.3 meters and its main lithology includes argillaceous limestone and shale. The lower boundary with the Sarvak Formation indicates a disconformity with dissolution holes and iron oxide bearing fragments, and its upper boundary with the Pabdeh Formation indicates a disconformity with a 30 cm thick key horizon containing phosphate nodules and manganese oxide traces. In this study, by identifying 66 species belonging to 22 genera of planktonic foraminifera, 9 biozones were identified and introduced based on the Tethys standard biozonation of Permoli Silva and Verga (2004). The age of the Gurpi Formation based on identified biozones is determined from the early Santonian to the late Maastrichtian. The K/Pg boundary is located at the end of the key horizon containing phosphate nodules and correlates with the lithostratigraphic boundary of the Gurpi and Pabdeh formations.
Exploration and Mining
Amir Salimi; Samaneh Barak; Mahyar Yousefi
Abstract
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical ...
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An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical data of the Neysian region. The optimal U-values obtained by this method for each sample were successfully utilized to separate the abnormal and background samples, accurately. In addition, based on the optimal distance of each sample, the abnormal samples identified in the previous step were classified in terms of geochemical intensity into strong, medium and weak samples. The goodness of U-spatial statistics performance in identifying abnormal areas were validated using drilled boreholes in the area. The U-spatial statistics not only succeeded in correctly identifying anomalous samples, but it also correctly identified some samples as the background whiles they had been recognized as anomaly by a non-structural method. All results obtained were validated by the several drilled boreholes.
Petrology
Shima Shomali; Mansour Ghorbani; Mohamad Reza Ghasemi
Abstract
The Marphioon pluton in the central part of Urmia-Dokhtar magmatic arc is among the Neotethyan oceanic lithosphere subduction-related intrusions. The composition of this pluton changes from granodiorite to tonalite. Marphioon granitoid gives rise to contact aureole zone with different peripheral thicknesses. ...
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The Marphioon pluton in the central part of Urmia-Dokhtar magmatic arc is among the Neotethyan oceanic lithosphere subduction-related intrusions. The composition of this pluton changes from granodiorite to tonalite. Marphioon granitoid gives rise to contact aureole zone with different peripheral thicknesses. U-Pb geochronology of a sample from southern outcrop suggests that these rocks have crystallized at 18.89±0.20 Ma in Early Miocene.These rocks belong to medium-K calc-alkaline series with I-type affinities. In terms of geodynamic setting, this intrusion is classified as volcanic arc granites and active continental margin granites. Qualitative interpretation of aeromagnetic data suggested a diorite to gabbroic composition due to high magnetic susceptibility.The Marphioon intrusion is strongly tectonized due to faulting. Basement dextral strike-slip faults and their sinistral conjugates are potential mechanisms for its exposure. It seems that the Marphioon magma in an active continental margin, originated from the partial melting of the lower continental crust with the involvement of mantle-derived melts, where mafic magma in mantle wedge has provided optimal temperature and fluids for this melting in the lower crust. Collectively, Marphioon intrusion seems to be emplaced during the transition time from subduction to collision in the Urmia-Dokhtar magmatic arc contemporaneous with the closure of the Neotethyan ocean.
Petroleum geology
Sadegh Barati Boldaji; Ebrahim Sefidari; Houshang Mehrabi; Seyed Mohammad Zamanzadeh
Abstract
Geochemical evaluation of potential source rocks in Foroozan Field is carried out based on Rock-Eval pyrolysis and vitrinite reflectance analyses. For getting the results, 101 samples for Rock-Eval pyrolysis and 11 samples for vitrinite reflectance analysis were selected from Gurpi, Sarvak, Kazhdumi, ...
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Geochemical evaluation of potential source rocks in Foroozan Field is carried out based on Rock-Eval pyrolysis and vitrinite reflectance analyses. For getting the results, 101 samples for Rock-Eval pyrolysis and 11 samples for vitrinite reflectance analysis were selected from Gurpi, Sarvak, Kazhdumi, Dariyan, Gadvan, Upper Fahliyan, and Neyriz formations cuttings. The results were used to determine the quantity, quality, and maturity of organic matter and show that the average content of organic matter in the studied formations range from poor to very good. According to the interpretations, the type of organic matter in the Gurpi, Sarvak, Upper Fahliyan, and Neyriz formations are mostly type III kerogen, and they have not reached to appropriate maturity. However, the Kazhdumi, Dariyan, and Gadvan formations mostly show type II kerogen which is not mature enough and have not yet entered the oil window. This group of formations can be considered suitable source rocks in the Foroozan field. Despite these formations are at the onset of the oil window, they have not produced hydrocarbon yet. Therefore, these formations or their equivalents in the deeper parts of the basin could be considered as active source rocks.
Stratigraphy and Palaeontology
Fatemeh Rezvannia; Hossein Mosaddegh; Bijan Biranvand; Vahid Tavakoli; Galina Nestell; َAhmad Yahyaei
Abstract
One of the most important carbonate gas reservoirs in the Zagros and Persian Gulf sedimentary basins is the Dalan Formation. This research investigates the microfacies, lithostratigraphy, and sequences of carbonate-evaporite deposits in the Lower member of the Dalan and the Nar member belonging to the ...
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One of the most important carbonate gas reservoirs in the Zagros and Persian Gulf sedimentary basins is the Dalan Formation. This research investigates the microfacies, lithostratigraphy, and sequences of carbonate-evaporite deposits in the Lower member of the Dalan and the Nar member belonging to the Guadalupian series with a total thickness of 2402 meters in four wells namely A, D, E, and G located in the eastern part of the Qatar-Persian arc in the Persian Gulf. The study of 340 thin sections prepared from the drill-ing cutting pieces with 2-meter intervals of well E, and a review of documents related to other wells. this led to the identification of 20 species belonging to 14 genera of foraminifera and the foraminiferal assemblages consisting of 65 species belonging to 25 genera. A foraminiferal biozone was recognized in well E, assigned to the Wordian. - Capitanian: Pachyphloia- Globivalvulina- Hemigordius, Assemblage Zone. Additionally, 11 microfacies, are distributed in five environments (sabkha, intertidal, lagoon, shoal, and shallow marine).
Economic Geology
Mehdi Moradi; Ebrahim Tale Fazel
Abstract
Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open ...
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Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open space-filling, comb, and disseminated textures are important mineralization textures that were formed in quartz-sulfide±gold veins (vein I) and quartz-barite-galena (vein II), which and cut later by carbonate veins (vein III). The homogenization temperature (Th) and salinity of the fluid inclusions, respectively, with an average temperature of 180 °C and salinity of 0.2 wt% NaCl eq. (vein I), 155 °C and 1.6 wt% NaCl eq. (vein II), and 135 °C and 1.5 wt% NaCl eq. (vein III). The values of δ34S in sulfide minerals of veins I and II are between +0.1 to ‒3‰ (δ34SH2S between ‒0.3 to +0.4‰), which indicates a single magmatic source for sulfur. The results of this research reveal that the existence of hydrostatic conditions (e.g., boiling) in the Mouchesh deposit has caused H2S releasing from the hydrothermal fluid, the decrease in the solubility of the bisulfide complex Au(HS)‒2, and ultimately the gold instability.
Economic Geology
Pooya Seyed Salehi Naeini; Saeid alirezaei
Abstract
The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic ...
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The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic alterations. They occur as linear features across faults and fractures, as well as massive bodies of variable sizes, and are comparable, at regional scale, to lithocaps developed in the upper parts of the porphyry systems. The silicic-argillic zones are mineralized with gold at variable grades. Gold occurs mostly as submicroscopic particles of electrum and native gold. Pyrite, variably oxidized at surface and shallow levels, is the main metallic mineral, associated with trace sulfosalts, tetrahedrite and enargite. Minor malachite staining locally occurs in the ore zones. The geologic setting, hydrothermal alteration, ore mineralogy and texture/structure allow the Kharestan-Bidester to be compared with high-sulfidation epithermal systems.
Petrology
Ghasem Ghorbani; Hanieh Dadgar; Hadi Shafaii Moghadam
Abstract
The mantle sequence of the Kuh Siah ophiolitic suite is located at N Sabzevar and consists of harzburgite, dunite,, lherzolite, pyroxenite, and chromitite lenses. Fo% of olivines in peridotites are between 90-97%, and they have a relatively low NiO and are plotted in the Ezubonin-Mariana peridotites. ...
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The mantle sequence of the Kuh Siah ophiolitic suite is located at N Sabzevar and consists of harzburgite, dunite,, lherzolite, pyroxenite, and chromitite lenses. Fo% of olivines in peridotites are between 90-97%, and they have a relatively low NiO and are plotted in the Ezubonin-Mariana peridotites. The Al2O3 content of orthopyroxene in harzburgites and lherzolites is relatively low and shows a tendency towards orthopyroxenes of forearc-abyssal peridotites. The clinopyroxene in the pyroxenites also has a low Al2O3 and TiO2 content and has a tendency to be in a forearc peridotite field. While this mineral in harzburgite and lherzolites have a higher content of Al2O3 and TiO2 and plots in the abyssal peridotites field. The spinel in lherzolites has a tendency to oceanic peridotites, while t in harzburgites shows a tendency to forearc and oceanic peridotites. The spinels in dunites have a high Cr# and seem derived from a boninitic melt and at high degrees of partial melting from a depleted mantle source under hydrous conditions. According to the minerals chemistry characteristics, the evolution of this mantle sequence has been involved in a supra-subduction zone environment and developed due to the northward subduction of the Sabzevar Ocean under the Alborz plate.
Petrology
Seyevahid Shahrokhi
Abstract
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic ...
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The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic rocks. The minerals set of granodiorite mass with color leucocratic to mesocratic index mainly minerals quartz, plagioclase, orthose and microcline and secondary minerals biotite, muscovite, zircon, garnet, apatite, rutile, leucoxene, and sphene. The indicator mineral of ferromagnesian in these rocks is biotite, which has a primary nature rich in magnesium and poor in chlorine in composition. The value of Fe/Fe+Mg ratio shows an average 0.44(apfu), that indicates that the studied micas are placed in the range of biotite and between siderophiles and anite poles. The average crystallization temperature of biotites is 681ºC and the average formation pressure is 2.95kb based on the total aluminum of biotites, which indicates formation at a shallow depth. Based on the proportions of MgO- FeO-Al2O3 in biotites, the magma that produced this mineral is of the calc-alkaline type. The existence of relatively high fugacity of oxygen and oxidant environment indicates magma of mantle-crust origin and host rock of magnetite granitoid series and I-type granitic rock for biotites.
Geological Environment and Engineering
razieh Lak; Ali Mohammadi; Javad Darvishikhatooni; Elnaz Aghaali
Abstract
Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic ...
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Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic features, (e.g. river truck channel depth, slope, sinuosity, river flood plain width and slope), illegal construction on the river legal boundary, as well as the effect of present-day climate change (change in annual rainfall precipitation and patterns, especially in El Niño conditions), cause environmental hazards such as extreme floods in urban areas. Imamzadeh Davood village is a religious-tourist place in the central the Alborz In this research, we investigated the 28th July, 2022 Imamzadeh Davood flood controlling factors and its effect on low-stream village (Imamzadeh Davood) and provided scientific solutions to decrees and prevent the destructive effect of future potential floods. The unusual extreme flood occurred after heavy and sudden rain in July (usually the area receives almost 0 cm of precipitation), causing a large volume of high-density mud flow with highly destructive power in the upper catchment.
Stratigraphy and Palaeontology
JAVAD SAADATNEJAD
Abstract
Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive ...
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Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive beds. It lies conformably, with a coarse grain sandstone bed, on top of the Laleband formation . Its upper contact is unconformable and sharp under the conglomerate beds of Javaherdeh formation. In this study 29 species of plant macrofossils from 13 genera were studied and introduced, including orders of Equisetales, Osmundales, Filicales, Cycadales, Bennettitales, Ginkgoales and Coniferales and an unknown reproductive organ. On the basis of the occurrence of index fossils such as Cladophlebis nebbensis, Nilssonia brevis, Dictyozamites asseretoi, Taeniopteris reversa, Taeniopteris tenuinervis and Baiera muensteriana Rhaetian age, and based on the occurrence of index taxa such as Dictyophyllum exile, Pterophyllum aequale and Pterophyllum bavieri, Late Rhaetian age is proposed for this assemblage. In this study, Ginkgoites whitbiensis from Iran and Taeniopteris reversa from Alborz are recorded for the first time. Clathropteris elegans, Nilssonia harrisi, Ginkgoites parasingularis and Ginkgoites lepida are recorded for the first time from Late Triassic beds of Iran