Geochemistry of microgranular enclaves in Aligoodarz Jurassic arc pluton, western Iran: implications for enclave generation by rapid crystallization of cogenetic granitoid magma   总被引：2，自引：0，他引：2  

Amir Esna-Ashari  Jamshid Hassanzadeh  Mohammad-Vali Valizadeh 《Mineralogy and Petrology》2011,101(3-4):195-216

Microgranular enclaves are common in the Jurassic Aligoodarz granitoids of western Iran. Enclaves Enclosed in Granodiorite (EEG) and Enclaves Enclosed in Tonalite (EET) are different but they overlap their hosts on variation diagrams. The EEG is compositionally intermediate between tonalite and granodiorite. Mixing between tonalitic and granodioritic magmas and fractional crystallization are two models examined as the origin of the EEG. Field, textural, mineralogical and chemical observations suggest that chemical equilibration, common in magma mixing, was not attained between the EEG and its host. This, together with other observations does not support magma mixing as a mechanism for forming the EEG. Alternatively, excessive nucleation of biotite ± Fe-Ti-oxides ± amphibole by rapid cooling at borders of a shallow magma chamber and later fragmentation and dispersal by dynamic arc plutonism best explains the EEG. However, channeling of a new magma into the nearly solid tonalitic host explains formation of the EET.  相似文献   

Causes and extent of environmental impacts of landslide hazard in the Himalayan region: a case study of Murree, Pakistan   总被引：2，自引：2，他引：0  

Atta-ur-Rahman  Amir Nawaz Khan  Andrew E. Collins  Fareen Qazi 《Natural Hazards》2011,57(2):413-434

Pakistan is located at the cross-roads of plate boundaries, experiencing multiple hazards of earthquake, flood, drought, water-logging, salinization and recurrent landslides. This paper examines the causes and environmental impacts of frequently occurring landslide hazards in the Murree area of Pakistan??s Himalayan region. These are wide ranging in nature and in terms of the damage that result. The area under research was divided into eight blocks and randomly data collected. It was observed that landslides mostly occur along the road network and disturbed slopes. Immature geology, a wide variation in climate and degradation of the natural resource-base were found to be some of the causal factors responsible for the landslide hazards. During the past three decades, rapid expansion of urban zones contributed to the changing vulnerability of the area. The analysis revealed that a large majority of the households (75%) in the area have been directly or indirectly affected by landslide hazards. Damages to already scarce agricultural land, infrastructure and other properties are each year a regular and escalating phenomenon. Landslide size, frequency and consequent costs of damage have increased considerably.  相似文献   

Assessment of the Design of an Experimental Cover with Capillary Barrier Effect Using 4 Years of Field Data     

Amir M. Abdolahzadeh  Benoit Lacroix Vachon  Alexandre R. Cabral 《Geotechnical and Geological Engineering》2011,29(5):783-802

One important step in the design of inclined covers with capillary barrier effect (CCBE) is the determination of the water diversion length (DL). Numerical simulations can predict the DL more precisely than steady-state analytical solutions. Nevertheless, as simplified methods have always been part of engineering design, the application of analytical solutions with conservative boundary conditions, may allow engineers to make reasonable predictions, particularly during the pre-feasibility stage of a project. In this study, a CCBE was designed, constructed and instrumented at the Saint-Tite-des-Caps landfill, Quebec, Canada. This CCBE included a seepage control layer superimposing a sand-gravel capillary barrier. The seepage control layer was made up of deinking by-products (DBP), an industrial by-product that was previously disposed of as waste. The capillary barrier was designed using an adaptation of the Ross analytical solution and the scenario considered was that of steady-state flow during constant seepage flow applied uniformly at the top of the sand-gravel capillary barrier. Although these conditions appear simplistic, they were deemed reasonable because placement of the seepage control layer on the top of the capillary barrier led to very low suctions at the interface, thereby allowing uniform downward seepage rates, limited by the saturated hydraulic conductivity of the DBP. In this paper, a discussion about the behaviour of the cover system based on 4 years of field data from several instruments is presented. The challenge of using DBP, more precisely the settlement of the DBP layer and its impact on k _sat , is also assessed. The DL was reassessed considering the new k _sat . A discussion on the validity of employing analytical solutions to determine DL is also presented. This paper illustrates how certain variables affect the design of inclined CCBEs that include a highly compressible material as seepage control layer.  相似文献   

DISCUSSION OF "In Situ Soil Remediation Using Vapor Extraction Wells, Development and Testing of a Three-Dimensional Finite-Difference Model," by Mansour Sepehr and Zohrab A. Samani     

Amir Gamliel 《Ground water》1993,31(6):1033-1034

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Re-appraisal of earthquake catalog in the Pamir―Hindu Kush region,emphasizing the early and modern instrumental earthquake events     

Rahman  Zahid  Rehman  Khaista  Ali  Wajid  Ali  Amir  Burton  Paul  Barkat  Adnan  Ali  Asghar  Qadri  S. M. Talha 《Journal of Seismology》2021,25(6):1461-1481

Journal of Seismology - The Pamir-Hindu Kush region is seismically the most dynamic and active zone that went through many devastating earthquakes. While much research is ongoing to produce seismic...  相似文献   

Electrochemical Treatment of Dye Solution by Oxalate Catalyzed Photoelectro‐Fenton Process Using a Carbon Nanotube‐PTFE Cathode: Optimization by Central Composite Design     

Ali R. Khataee  Mahmoud Zarei  Amir R. Khataee 《洁净——土壤、空气、水》2011,39(5):482-490

Decolorization of C.I. Basic Blue 3 (BB3) by oxalate catalyzed photoelectro‐Fenton process based on carbon nanotube‐polytetrafluoroethylene (CNT‐PTFE) electrode as cathode under visible light was studied. A comparison of electro‐Fenton, photoelectro‐Fenton, and photoelectro‐Fenton/oxalate processes for decolorization of the solution containing BB3 has been performed. The results showed that color removal follows the decreasing order: photoelectro‐Fenton/oxalate > photoelectro‐Fenton > electro‐Fenton. Response surface methodology (RSM) was employed to assess individual and interactive effects of the four main independent parameters on the decolorization efficiency. A central composite design (CCD) was employed for optimization of photoelectro‐Fenton/oxalate treatment of BB3. The analysis of variance (ANOVA) showed a high coefficient of determination value (R² = 0.958) and satisfactory prediction second‐order regression. This study clearly showed that RSM was one of the suitable methods to optimize the operating conditions.  相似文献   

Closure to ＂Discussion on ＇Optimum placement and characteristics of velocity-dependent dampers under seismic excitation＇ by SA Mousavi and AK Ghorbani-Tanha＂ by Izuru Takewaki     

Seyed Amin  Mousavi Amir  K.  Ghorbani-Tanha 《地震工程与工程振动(英文版)》2013,12(4):681-682

The authors would like to thank the discusser for his considerations and comments. The discusser believes that some of the derived formulations need to be referred to his previously published works and also some related studies have not been cited.  相似文献   

Study of Danjon limit in moon crescent sighting     

Amir Hasanzadeh 《Astrophysics and Space Science》2012,339(2):211-221

About 70 years ago “André Danjon” a French astrophysicist showed that as elongation of the moon decreases the arc length of crescent gets less too. By studying the recent observational data, he concluded that at 7 degree elongation, the length of arc (cusp to cusp) will reach zero degree. Today, this value is named as Danjon limit, which points to the limit at which the moon crescent is formed. Danjon believed that the effective factor for occurring this limit was the shadows of moon’s mountains. Later researchers have obtained different values for this limit. In this research based on the new data, the decreasing dependence of length of arc versus elongation was obtained. The results show that the Danjon limit is about 5 degrees. The effective factors to form the Danjon limit are then given and discussed. By considering the effects of astronomical seeing and shadows of lunar features, the values of the arc length were calculated and compared with the observational data curve. The results of this study show good agreement with the observational data. The present research shows that the above-mentioned effects can reduce the length of arc. The effect of libration and roughness of the lunar terrain of the moon in forming the moon crescent were also considered, and the possibility of observing thinner crescents by photometric model and breaking the Danjon limit were given.  相似文献   

Landslide Hazard in the Nainital township,Kumaun Himalaya,India: the case of September 2014 Balia Nala landslide     

Vikram Gupta  Rajinder K. Bhasin  Amir M. Kaynia  Ruchika Sharma Tandon  B. Venkateshwarlu 《Natural Hazards》2016,80(2):863-877

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Effect of Temporal Changes in Air Injection Rate on Air Sparging Performance Groundwater Remediation          下载免费PDF全文

Asaf Ben Neriah  Amir Paster 《Ground water》2016,54(6):851-860

Air sparging (AS) is a commonly applied method for treating groundwater contaminated with volatile organic compounds (VOCs). When using a constant injection of air (continuous mode), a decline in remediation efficiency is often observed, resulting from insufficient mixing of contaminants at the pore scale. It is well known that turning the injection on and off (pulsed mode) may lead to a better remediation performance. In this article, we investigate groundwater mixing and contaminant removal efficiency in different injection modes (i.e., continuous and pulsed), and compare them to those achieved in a third mode, which we denote as “rate changing.” In this mode, injection is always on, and its rate is varying with time by abrupt changes. For the purpose of this investigation, we conducted two separate sets of experiments in a laboratory tank. In the first set of experiments, we used dye plume tracing to characterize the mixing induced by AS. In the second set of experiments, we contaminated the tank with a VOC and compared the remediation efficiency between the different injection modes. As expected, we observed that time‐variable injection modes led to enhanced mixing and contaminant removal. The decrease in contaminant concentrations during the experiment was found to be double for the “rate changing” and “pulsed” modes compared to the continuous mode, with a slightly preferable performance for the “rate changing” mode. These results highlight the critical role that mixing plays in AS, and support the need for further investigation of the proposed “rate changing” injection mode.  相似文献