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1.
A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran) 总被引：3，自引：0，他引：3
Recent geochemical studies of volcanic rocks forming part of the ophiolites within the Zagros and Naien-Baft orogen indicate that most of them were developed as supra-subduction ophiolites in intra-oceanic island arc environments. Intra-oceanic island arcs and ophiolites now forming the Naien-Baft zone were emplaced southwestward onto the northeastern margin of the South Sanandaj–Sirjan Zone, while those now in the High Zagros were emplaced southwestward onto the northern margin of Arabia. Thereafter, subduction continued on opposite sides of the remnant oceans. The floor of Neo-Tethys Ocean was subducted at a low angle beneath the entire Sanandaj–Sirjan Zone, and the floor of the Naien-Baft Ocean was subducted beneath the Central Iranian Micro-continent. The Naien-Baft Ocean extended into North-West Iran only temporarily. This failed ocean arm (between the Urumieh-Dokhtar Magmatic Assemblage and the main Zagros Thrust) was filled by thick Upper Triassic–Upper Jurassic sediments. The Naien-Baft Ocean finally closed in the Paleocene and Neo-Tethys closed in the Early to Middle Eocene. After Arabia was sutured to Iran, the Urumieh-Dokhtar Magmatic Assemblage recorded slab break-off in the Middle Eocene. 相似文献
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An accurate estimate of the groundwater inflow to a tunnel is one of the most challenging but essential tasks in tunnel design and construction. Most of the numerical or analytical solutions that have been developed ignore tunnel seepage conditions, material properties and hydraulic-head changes along the tunnel route during the excavation process, leading to inaccurate prediction of inflow rates. A method is introduced that uses MODFLOW code of GMS software to predict inflow rate as the tunnel boring machine (TBM) gradually advances. In this method, the tunnel boundary condition is conceptualized and defined using Drain package, which is simulated by dividing the drilling process into a series of successive intervals based on the tunnel excavation rates. In addition, the drain elevations are specified as the respective tunnel elevations, and the conductance parameters are assigned to intervals, depending on the TBM type and the tunnel seepage condition. The Qomroud water conveyance tunnel, located in Lorestan province of Iran, is 36 km in length. Since the Qomroud tunnel involved groundwater inrush during excavating, it is considered as a good case study to evaluate the presented method. The groundwater inflow to this tunnel during the TBM advance is simulated using the proposed method and the predicted rates are compared with observed rates. The results show that the presented method can satisfactorily predict the inflow rates as the TBM advances. 相似文献
4.
Ahmad Zalooli David Martín Freire-Lista Mashalah Khamehchiyan Mohammad Reza Nikudel Rafael Fort Shahram Ghasemi 《Environmental Earth Sciences》2018,77(8):315
Durability of building stones is an important issue in sustainable development. Crystallization of soluble salts is recognized as one of the most destructive weathering agents of building stones. For this reason, durability of Ghaleh-khargushi rhyodacite and Gorid andesite from Iran was investigated against sodium sulfate crystallization aging test. Petrographic and physico-mechanical properties and pore size distribution of these stones were examined before and after the aging test. The characteristics of the microcracks were quantified with fluorescence-impregnated thin sections. Durability and physico-mechanical characteristics of Ghaleh-khargushi rhyodacite are mainly influenced by preferentially oriented preexisting microcracks. Stress induced by salt crystallization led to the widening of preexisting microcracks in Ghaleh-khargushi rhyodacite, as confirmed by the pore size distributions before and after the aging test. The preexisting microcracks of Gorid andesite were attributed to the mechanical stress induced by contraction of lava during cooling. The number of transcrystalline microcracks was significantly increased after the aging test. The degree of plagioclase microcracking was proportional to its size. Durability of the studied stones depends on initial physico-mechanical properties, pore size distribution, and orientation of microcracks. Initial effective porosity is found to be a good indicator of the stones’ durability. Salt crystallization resulted in an increase in the effective porosity with a parallel decrease in the wave velocities. Surface microroughness parameters increased with the development of salt crystallization-induced microcracking. Gorid andesite showed higher quality and durability than Ghaleh-khargushi rhyodacite. 相似文献
5.
Gozari Mohsen Bahador Nim Jassbi Amir Rez Mortazavi Mohammad Seddiq Hamzehei Sam Eftekhar Ebrahim 《海洋学报(英文版)》2019,38(12):84-90
Screening bioactive natural products from bacteria is a determinative step in the drug discovery programs. The present study aim to isolate actinobacteria from the Oman Sea sediments for determining the effects of different culture media and treatments on the yield of the isolation process, and measure the DPPH radical scavenging and Artemia cytotoxic activity of culture extracts of the actinobacterial isolates. A total of 290 actinobacterial isolates were collected from 14 sediment samples. Heat treatment(40.68%) and M_4 medium(29.31%) exhibited the maximum isolation rates of actinobacteria. Streptomyces isolates were dominantly distributed in all of the investigated stations according to 16 S rRNA gene sequencing. The distribution pattern of Streptomyces followed a depth-dependent frequency trend, whereas the members of rare genera including Micromonospora, Nocardia Actinoplanes, Nocardiopsis, Saccharopolyspora and Crossiella were distributed in deeper stations. Approximately,25% of the examined isolates could scavenge 90% of 10~(–4) mol/L DPPH solutions at 1 250 μg/mL final concentration of their ethyl acetate culture extracts. Furthermore, the most potent extracts could scavenge DPPH radicals with IC50 ranges from 356.8 to 566.4 μg/mL. Brine shrimp cytotoxicity tests showed that 38.88% of the examined culture extracts exhibited LC_(50) lower than 1 000 μg/mL against the Artemia cells. Moreover, the most potent culture extracts exhibited LC_(50) range from 335.4 to 534.4 μg/mL. Phylogenetic analysis by 16 S rRNA gene sequence revealed that the OS 005, OS 263 and OS 157 closely related to Streptomyces djakartensis, Streptomyces olivaceus and Nocardiopsis dassonvillei respectively. These results suggested the widespread distribution of the antioxidant and cytotoxic producing actinobacteria in the Oman Sea sediments, which could be considered as promising candidates for the discovery of microbial bioactive compounds. 相似文献
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The Kazhdumi Formation of the Bangestan Group is a well-known source rock that has produced abundant oil in most petroleum fields in the Zagros Basin, which stretches from northwest to southwest Iran over hundreds of kilometres. The formation reaches a thickness of 230 m at the type section in northwest Zagros but thins out to 40–50 m in wells studied from the South Pars giant petroleum field, where it comprises mainly grey shales with occasional intercalations of marls and sandstones. South Pars, best known as the Iranian part of the world's largest non-associated gas field, contains small quantities of oil above and below the Kazhdumi Formation. 相似文献
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Summary The impact of the Arctic Oscillation (AO) on the winter surface air temperature (SAT) over Iran is demonstrated. Winter SAT
data for 50 years (1951–2000) are analyzed for the negative and the positive AO phases. Using the Median Sequential Correlation
Analysis (MSCA) technique it is shown that the winter SAT is negatively correlated to the winter AO index for most parts of
Iran. The winter AO index accounts for about 14% to 46% of the winter SAT variance. The positive (negative) SAT anomaly is
found to be associated with the onset of the negative (positive) phase. The overall probability of below long-term mean temperature
during the positive and the negative phases are estimated to be around 70% and 25%, respectively. For the negative phase,
westerly winds that originate from the warm Atlantic regions increase over Iran and consequently positive temperature anomalies
are found across the country. The positive AO phase is accompanied by northerly winds that allow continental polar and arctic
air masses to move into Iran, producing below normal temperatures. The summer AO is found to explain about 25–32% of the winter
SAT variance in Iran. The reason for this is explained by the significant correlation (+0.38) between the summer and the following
winter AO indices. These results indicate that the summer climate is linked to changes in atmospheric circulation which persist
through to the following autumn and winter. 相似文献
8.
The Qolqoleh gold deposit is located in the northwestern part of the Sanandai‐Sirjan Zone, northwest of Iran. Gold mineralization in the Qolqoleh deposit is almost entirely confined to a series of steeply dipping ductile–brittle shear zones generated during Late Cretaceous–Tertiary continental collision between the Afro‐Arabian and the Iranian microcontinent. The host rocks are Mesozoic volcano‐sedimentary sequences consisting of felsic to mafic metavolcanics, which are metamorphosed to greenschist facies, sericite and chlorite schists. The gold orebodies were found within strong ductile deformation to late brittle deformation. Ore‐controlling structure is NE–SW‐trending oblique thrust with vergence toward south ductile–brittle shear zone. The highly strained host rocks show a combination of mylonitic and cataclastic microstructures, including crystal–plastic deformation and grain size reduction by recrystalization of quartz and mica. The gold orebodies are composed of Au‐bearing highly deformed and altered mylonitic host rocks and cross‐cutting Au‐ and sulfide‐bearing quartz veins. Approximately half of the mineralization is in the form of dissemination in the mylonite and the remainder was clearly emplaced as a result of brittle deformation in quartz–sulfide microfractures, microveins and veins. Only low volumes of gold concentration was introduced during ductile deformation, whereas, during the evident brittle deformation phase, competence contrasts allowed fracturing to focus on the quartz–sericite domain boundaries of the mylonitic foliation, thus permitting the introduction of auriferous fluid to create disseminated and cross‐cutting Au‐quartz veins. According to mineral assemblages and alteration intensity, hydrothermal alteration could be divided into three zones: silicification and sulfidation zone (major ore body); sericite and carbonate alteration zone; and sericite–chlorite alteration zone that may be taken to imply wall‐rock interaction with near neutral fluids (pH 5–6). Silicified and sulfide alteration zone is observed in the inner parts of alteration zones. High gold grades belong to silicified highly deformed mylonitic and ultramylonitic domains and silicified sulfide‐bearing microveins. Based on paragenetic relationships, three main stages of mineralization are recognized in the Qolqoleh gold deposit. Stage I encompasses deposition of large volumes of milky quartz and pyrite. Stage II includes gray and buck quartz, pyrite and minor calcite, sphalerite, subordinate chalcopyrite and gold ores. Stage III consists of comb quartz and calcite, magnetite, sphalerite, chalcopyrite, arsenopyrite, pyrrhotite and gold ores. Studies on regional geology, ore geology and ore‐forming stages have proved that the Qolqoleh deposit was formed in the compression–extension stage during the Late Cretaceous–Tertiary continental collision in a ductile–brittle shear zone, and is characterized by orogenic gold deposits. 相似文献
9.
F. Ghasemi F. Tabandeh Ph.D. B. Bambai Ph.D. K. R. S. Sambasiva Rao Ph.D. 《International Journal of Environmental Science and Technology》2010,7(3):457-464
Detoxification of synthetic dyes is one of the main challenges in clearing textile industry wastes. Biodegradation of azo-dyes using Phanerochaete chrysosporium is one the most environmentally friendly methods available. The main enzymes responsible for mycodecolorization process are lignin and manganese peroxidases. Here, optimization of expression conditions has been carried out with manipulating culture condition and nutrient sources. Therefore, the effects of buffer and temperature as well as nitrogen source on lignin peroxidase and manganese peroxidase production were investigated at two levels and four levels, respectively. For this purpose, P. chrysosporium RP78 based on Taguchi design of experiment has been applied. Maximum lignin and manganese peroxidase activities of 182 ± 2.5 U/L and 850 ± 41 U/L were obtained under predicted optimum conditions, respectively. Thereby, about 100 % decolorization was achieved after 24 h for two most widely used groups of azo dyes in textile industry consisting reactive and acidic. The physical adsorption of the azo dyes by mycelia was not significant which indicated that the enzymatic degradation of the dyes was occurred. Time profile of these enzymes showed that manganese peroxidase was peaked on 9th day while lignin peroxidase peaked on 13th day and remained stable in the culture. The extracellular expression profiles of both were studied by 2 dimensional gel electrophoresis to partially characterize the enzymes. 相似文献
10.
M. Ghasemi N. Ghasemi G. Zahedi S. R. W. Alwi M. Goodarzi H. Javadian 《International Journal of Environmental Science and Technology》2014,11(7):1835-1844
In this study, the adsorption behavior of Ni(II) in an aqueous solution system using natural adsorbent Peganum harmala-L was measured via batch mode. The prepared sorbent was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, N2 adsorption–desorption and pHzpc. Adsorption experiments were carried out by varying several conditions such as contact time, metal ion concentration and pH to assess kinetic and equilibrium parameters. The equilibrium data were analyzed based on the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. Kinetic data were analyzed using the pseudo-first-order, pseudo-second-order and intra-particular diffusion models. Experimental data showed that at contact time 60 min, metal ion concentration 50 mg/L and pH 6, a maximum amount of Ni(II) ions can be removed. The experimental data were best described by the Langmuir isotherm model as is evident from the high R 2 value of 0.988. The adsorption capacity (q m) obtained was 68.02 mg/g at an initial pH of 6 and a temperature of 25 °C. Kinetic studies of the adsorption showed that equilibrium was reached within 60 min of contact and the adsorption process followed the pseudo-first-order model. The obtained results show that P. harmala-L can be used as an effective and a natural low-cost adsorbent for the removal of Ni(II) from aqueous solutions. 相似文献