Qanat hazard in Iranian urban areas: explanation and remedies     

Ahmad Abbasnejad  Behnam Abbasnejad  Reza Derakhshani  Alireza Hemmati Sarapardeh 《Environmental Earth Sciences》2016,75(19):1306

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Erratum to: A spatio-temporal three-dimensional conceptualization and simulation of Dera Ismail Khan alluvial aquifer in visual MODFLOW: a case study from Pakistan     

Qadir  Anwar  Ahmad  Zulfiqar  Khan  Tahseenullah  Zafar  Mohammad  Qadir  Atwar  Murata  Mamoru 《Arabian Journal of Geosciences》2016,9(7):1-17

The Gour Oumelalen area exposes Paleoproterozoic (1.9 Ga) marbles and calc-silicate granulites. Some marbles show a specific mineralogy characterized by the presence of a highly aluminous clinopyroxene with Al₂O₃ content exceeding16 wt%. This clinopyroxene shows a marked zoning with a hedenbergitic core rimmed by fassaite. Phase relations are expressed by spectacular reaction textures in calc-silicate granulites as Opx + Cpx + Pl + H₂O  == > Grt + Qtz ± Am and Cpx + Ilm + Pl ± Mt = > Grt + Qtz + Spn. In olivine-bearing marbles, clinopyroxene and dolomite occur around olivine and calcite. According to thermodynamic modeling in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–Fe₂O₃ (NCFMASHTO) system, the first stage of metamorphism is located at 800 °C and 6–7 kbar, which is followed by an increase in pressure at 9–10 kbar and 800 °C and an isobaric cooling at 680 °C. The deduced anticlockwise P–T path is consistent with a granulitic metamorphism occurring in an active continental margin context.

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Using robust staged R-mode factor analysis and logistic function to identify probable Cu-mineralization zones in Khusf 1:100,000 sheets,east of Iran     

Majid Keykha Hoseinpoor  Ahmad Aryafar 《Arabian Journal of Geosciences》2016,9(2):157

Factor analysis method is a multivariate analysis technique that is widely used for the interpretation of stream sediment geochemical data. The purpose of factor analysis is describing the changes in a set of multi-element geochemical data by reducing the dimension of the data and variables to a number of factors that can present the hidden association between elements. Differences in mobility, physical, and chemical properties of the elements and the nature of the factor analysis method in which the matrix of all data is used cause paragenes elements not to be found on the output of factor analysis. In this research, to improve the output of factor analysis for deriving the best reagent multi-element mineralization, robust staged factor analysis method was used according to the close nature of geochemical data in order to identify the Cu-mineralization potential in Khusf 1:100,000 sheets located at the east of Iran. The robust staged factor analysis enhances the recognition of anomalous geochemical signatures and increases geochemical anomaly intensity and the percentage of the total explained variability of data. As indicated by the results of the study, few anomalous zones have been found in the study area. The observation of chalcopyrite and malachite mineralization in andesite and dacite–andesite rocks in a region during the field study confirms the effectiveness of the robust SFA technique. Such studies can be used by mine engineers and geologists for designing an optimum grid exploration on the next exploration steps.  相似文献   

Petrographical and geochemical signatures of Jurassic rocks of Chari Formation,Western India: implications for provenance and tectonic setting     

Shaista Khan  A. H. M. Ahmad  M. Masroor Alam  Adnan Quasim 《中国地球化学学报》2016,35(2):184-202

The sandstones of the Ridge and Athleta members of Chari Formation (Callovian-Oxfordian) exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium to coarse grained, poorly to well sorted, sub-angular to sub-rounded, and show low to medium sphericity. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic, and some basic rocks of Aravalli range and Nagarparkar massif. The petrofacies analysis reveals that these sandstones belong to the continental block and recycled orogen tectonic regime. The studied sandstones are modified by paleoclimate, distance of transport, and diagenesis. Mineralogically and geochemically, sandstones are classified as quartzarenite, subarkose, arkose, sublithic arenite, and wacke, respectively. The A-CN-K ternary plot and CIA, CIW, PIA, and ICV values suggest that the similar source rocks suffered moderate to high chemical weathering under a hot-humid climate in an acidic environment with higher \({\text{P}}_{{{\text{CO}}_{ 2} }}\). Generally good to strong correlations between Al₂O₃ and other oxides in these sediments indicate clay mineral control. The K₂O/Na₂O versus SiO₂ diagram indicates that the studied samples occupy passive margin fields but the SiO₂/Al₂O₃ versus K₂O/Na₂O plot suggests that the Athleta Sandstone and Ridge Sandstone fall within the passive margin field, while Ridge Shale falls within the active continental margin field.  相似文献   

Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex     

Ashima Saikia  Bibhuti Gogoi  Mansoor Ahmad  Talat Ahmad 《Journal of Earth System Science》2014,123(5):959-987

The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, cross-cutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.  相似文献   

Threat of glacial lake outburst flood to Tehsil Gupis from Khukush Lake, District Ghizer, Gilgit Baltistan, Pakistan     

Gohar Rehman  Sajjad Ahmad  Shuhab D. Khan  Fayaz Ali  Taqweemul H. Ali  Sadaf F. Khan 《Natural Hazards》2014,70(2):1589-1602

Glacial lake outburst flood (GLOF) is a powerful natural phenomenon that is very active in the Karakoram and Himalayas. This paper presents a case study from Gupis Tehsil in northern areas of Pakistan that is exposed to GLOFs from nine different glacial lakes in its upper catchment areas. Khukush Lake being the largest of all the glacial lakes has been studied and a flood attenuation model has been created for the whole Gupis Tehsil. This lake covers almost 2.2 km² of surface area, and its calculated volume is 2.6 × 10⁴ m³. In case of its outburst, the peak flow discharge is calculated to be 7,642 m³/s. The catchment area which contributes water and debris to the lake is 170 km². This lake is dammed by a glacial moraine, which is not strong enough to sustain the pressure for a longer period of time. Other factors that are reducing the reliability of the dam are the secondary hazards which are in direct contact with the lake, and in case of their reactivation, they can put severe impacts on the dam. There are eight potential sites of the snow avalanche activity where debris along with snow may fall directly into the lake producing a strong wave. This strong wave of water will increase the pressure on the dam and ultimately will increase the probability for its outburst. The presense of water springs towards the downstream side of the natural dam also indicate the presence of hidden channels passing through the dam which may weaken the shear strength of the dam. Almost 24 villages settled along either sides of the Gupis River are critically studied for the expected flood from Khukush Lake. With few exceptions, almost 20–25 % area of all the villages will be affected from this flood.  相似文献   

Effectiveness of zinc application to minimize cadmium toxicity and accumulation in wheat (Triticum aestivum L.)     

Saifullah  Nadeem Sarwar  Sadia Bibi  Mahtab Ahmad  Yong Sik Ok 《Environmental Earth Sciences》2014,71(4):1663-1672

Cadmium (Cd) is a highly toxic heavy metal and its presence in soil is of great concern due to the danger of its entry into the food chain. Among many others, proper plant nutrition is an economic and practicable strategy for minimizing the damage to plants from Cd and to decrease Cd accumulation in edible plant parts. The study was carried out to compare the effectiveness of soil and foliar applications of zinc (Zn) to minimize Cd accumulation in wheat grains. The results revealed that the exposure of plants to Cd decreased plant growth and increased Cd concentration in the shoots and grains of wheat, when compared with unexposed plants. Foliar application of 0.3 % zinc sulfate solution effectively decreased Cd concentration in wheat grains. Foliar application of Zn at a suitable concentration can effectively ameliorate the adverse effects of Cd exposure and decrease the grain Cd concentration of wheat grown in Cd-contaminated soil.  相似文献   

Evaluating Boolean,AHP and WLC methods for the selection of waste landfill sites using GIS and satellite images   总被引：2，自引：2，他引：0  

Himan Shahabi  Soroush Keihanfard  Baharin Bin Ahmad  Mohammad Javad Taheri Amiri 《Environmental Earth Sciences》2014,71(9):4221-4233

The city of Saqqez has a population of 140,000 people, making it one of the largest cities in Iran. Population growth, consumerism, and change in eating habits, such as the increased use of packaged products, is causing the accumulation of waste in this city to increase. In this study, the selection of a waste landfill site for Saqqez focused on 13 layers of geography information that was used by the IDRISI and Arc GIS software. Different models of the analytic multi-criteria decision-making process, such as an analytical hierarchy process (AHP), weighted linear combination (WLC), and Boolean logic, were used to manage layers to establish specific databases for urban waste landfills. Satellite images (Landsat ETM⁺ and SPOT 5), proposed sites and a land use map of the study area were also used. The results of this study indicated that two methods (AHP and WLC) in the early stages had better decision-making powers for locating landfill sites when compared to Boolean logic. Overlapping and compounding the similarities between these models in Arc GIS software, a 74-ha site was found. This site will be able to accept 130 tons of waste per day for the next 20 years.  相似文献   

Assessing the impacts of changing land cover and climate on Hokersar wetland in Indian Himalayas     

Shakil Ahmad Romshoo  Irfan Rashid 《Arabian Journal of Geosciences》2014,7(1):143-160

Monitoring the spatiotemporal changes in wetlands and assessing their causal factors is critical for developing robust strategies for the conservation and restoration of these ecologically important ecosystems. In this study, the spatiotemporal changes in the land cover system within a Himalayan wetland and its catchment were assessed and correlated using a time series of satellite, historical, and field data. Significant changes in the spatial extent, water depth, and the land system of the Hokersar wetland were observed from the spatiotemporal analysis of the data from 1969 to 2008. The wetland area has shrunk from 18.75 km² in 1969 to 13 km² in 2008 with drastic reduction in the water depth of the wetland. The marshy lands, habitat of the migratory birds, have shrunk from 16.3 km² in 1969 to 5.62 km² in 2008 and have been colonized by various other land cover types. The land system and water extent changes within the wetland were related to the spatiotemporal changes in the land cover and hydrometeorological variables at the catchment scale. Significant changes in the forest cover (88.33–55.78 km²), settlement (4.63–15.35 km²), and water bodies (1.75–0.51 km²) were observed in the catchment. It is concluded that the urbanization, deforestation, changes in the hydrologic and climatic conditions, and other land system changes observed in the catchment are the main causes responsible for the depleting wetland extent, water depth, and biodiversity by adversely influencing the hydrologic erosion and other land surface processes in the catchment. All these causes and effects are manifest in the form of deterioration of the water quality, water quantity, the biodiversity changes, and the decreasing migratory bird population in the wetland.  相似文献   

Rockfall hazard assessment at Ajanta Cave,Aurangabad, Maharashtra,India     

M. K. Ansari  M. Ahmad  Rajesh Singh  T. N. Singh 《Arabian Journal of Geosciences》2014,7(5):1773-1780

The Ajanta caves are situated in Deccan Trap basalt and declared as one of the World Heritage Sites by UNESCO. The present study aims to investigate and understand the damage of caves and to protect the life of the visitors from the rockfall phenomenon at and around the caves. Information related to the detached rock mass/block was acquired by using Barton–Bandis model in Universal Distinct Element Code. Parameters for rockfall simulation were determined by rigorous field study and laboratory experiment and then calibrated some of the parameters by back analysis. RocFall 4.0 program has been used to calculate maximum bounce heights, total kinetic energies, and translational velocities of the falling blocks of different weights. The maximum bounce height varies from 14.0 to 19.0 m for the weight of the block size ranging from 500 to 2,000 kg, whereas the maximum velocity and maximum kinetic energy are 30.0 m/s and 917.66 kJ, respectively. Finally, the results of simulation have been used to find out the position of the barrier and its capacity to design the protection barrier. The barrier capacity was found to be 325 kJ for 2,000 kg of falling blocks at a height of 50.0 m.  相似文献