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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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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
4.
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
5.
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
6.
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
7.
Application of artificial intelligence techniques for predicting the flyrock distance caused by blasting operation 总被引：2，自引：0，他引：2
Ebrahim Ghasemi Hasel Amini Mohammad Ataei Reza Khalokakaei 《Arabian Journal of Geosciences》2014,7(1):193-202
Flyrock arising from blasting operations is one of the crucial and complex problems in mining industry and its prediction plays an important role in the minimization of related hazards. In past years, various empirical methods were developed for the prediction of flyrock distance using statistical analysis techniques, which have very low predictive capacity. Artificial intelligence (AI) techniques are now being used as alternate statistical techniques. In this paper, two predictive models were developed by using AI techniques to predict flyrock distance in Sungun copper mine of Iran. One of the models employed artificial neural network (ANN), and another, fuzzy logic. The results showed that both models were useful and efficient whereas the fuzzy model exhibited high performance than ANN model for predicting flyrock distance. The performance of the models showed that the AI is a good tool for minimizing the uncertainties in the blasting operations. 相似文献
8.
Flood frequency analysis based on simulated peak discharges 总被引：2，自引：0，他引：2
Flood frequency approaches vary from statistical methods, directly applied on the observed annual maximum flood series, to adopting rainfall–runoff simulation models that transform design rainfalls to flood discharges. Reliance on statistical flood frequency analysis depends on several factors such as the selected probability distribution function, estimation of the function parameters, possible outliers, and length of the observed flood series. Through adopting the simulation approach in this paper, watershed-average rainfalls of various occurrence probabilities were transformed into the corresponding peak discharges using a calibrated hydrological model. A Monte Carlo scheme was employed to consider the uncertainties involved in rainfall spatial patterns and antecedent soil moisture condition (AMC). For any given rainfall depth, realizations of rainfall spatial distribution and AMC conditions were entered as inputs to the model. Then, floods of different return periods were simulated by transforming rainfall to runoff. The approach was applied to Tangrah watershed in northeastern Iran. It was deduced that the spatial rainfall distribution and the AMCs exerted a varying influence on the peak discharge of different return periods. Comparing the results of the simulation approach with those of the statistical frequency analysis revealed that, for a given return period, flood quantiles based on the observed series were greater than the corresponding simulated discharges. It is also worthy to note that existence of outliers and the selection of the statistical distribution function has a major effect in increasing the differences between the results of the two approaches. 相似文献
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Farhadian Ali Ghasemi Ebrahim Hoseinie Seyed Hadi Bagherpour Raheb 《Geotechnical and Geological Engineering》2022,40(6):3343-3356
Geotechnical and Geological Engineering - Rock abrasivity index (RAI) and uniaxial compressive strength (UCS) are two key parameters for assessing abrasivity and durability of building stones,... 相似文献
10.
Summary This study attempts to find possible linkages between the NCP index and the winter temperature variability over Iran. The
investigation is based on statistical analysis of simple, partial and multiple correlations and also evaluation of composite
maps of the extreme NCP index and maps of correlation between atmospheric variables and the temperature time series.
Our results show that the NCP has a strong negative correlation with the winter temperature in Iran. Furthermore, combination
of both the NCP and the AO (Arctic Oscillation) indices improve the correlations in all stations, implying both NCP and AO
can be considered as major patterns for explaining the Iranian winter temperature variability. The results show that the positive
NCP is associated with enhanced precipitation and cloudy conditions, consequently causing below normal temperature over Iran.
The anomalies of OLR in this phase are also negative, implying a cloudy sky. For the negative NCP phase these results are
completely reversed. The correlation maps indicate that the NCP is negatively/positively correlated with winter Outgoing Long-wave
Radiation/precipitation over Iran. The results also show that the SLP and GPH patterns are quite different for the positive
and negative NCP phases over Iran. During the negative NCP a small cyclone is formed over the Arabian Sea causing a strong
easterly towards Iran. During the positive NCP this cyclone is removed. Our results show that for the positive NCP years an
upper-level trough is formed over northern Iran and the eastern Mediterranean. For the negative NCP years this trough becomes
weak and is located over central European regions. This trough is closely linked with the winter temperature over Iran. This
is expressed by a high correlation between 500-hPa geopotential height at this region and Iranian winter temperature.
Authors’ addresses: A. R. Ghasemi, Climate Research Center, Water Engineering Department, Agricultural Faculty, Shiraz University,
Shiraz, Iran; D. Khalili, Water Engineering Department, Agricultural Faculty, Shiraz University, Shiraz, Iran. 相似文献