Crystallization Conditions and Mineral Chemistry in the East of Tafresh,Central Iran,with Insights into Magmatic Processes     

Davood RAEISI  Hassan MRNEJAD 《《地质学报》英文版》2019,93(6):1755-1772

The Tafresh granitoids are located at the central part of the Urumieh-Dokhtar Magmatic Arc(UDMA) in Iran. These rocks, mainly consisting of diorite and granodiorite, were emplaced during the Early Miocene. They are composed of varying proportions of plagioclase + K-feldspar + hornblende ± quartz ± biotite. Discrimination diagrams and chemical indices of amphibole phases reveal a calc-alkaline affinity and fall clearly in the crust-mantle mixed source field. The estimated pressure, derived from Al in amphibole barometry, is approximately 3 Kb. The granitoids are I-type, metaluminous and belong to the calc-alkaline series. They are all enriched in light rare earth elements and large ion lithophile elements, depleted in high field strength elements and display geochemical features typical of subduction-related calc-alkaline arc magmas. Most crystal size distribution(CSD) line patterns from the granitoids show a non-straight trend which points to the effect of physical processes during petrogenesis.The presence of numerous mafic enclaves, sieve texture and oscillatory zoning along with the CSD results show that magma mixing in the magma chamber had an important role in the petrogenesis of Tafresh granitoids. Moreover, the CSD analysis suggests that the plagioclase crystals were crystallized in a time span of less than 1000 years, which is indicative of shallow depth magma crystallization.  相似文献   

Geochemical modeling,fate distribution,and risk exposure of potentially toxic metals in the surface sediment of the Shyok suture zone,northern Pakistan     

Liaqat Ali  Abdur Rashid  Seema Anjum Khattak  Xubo Gao  Shah Jehan  Asif Javed 《国际泥沙研究》2021,36(5):656-667

The objective of the current study was to assess the contamination of potentially toxic metals (PTMs) in weathered surface sediment, along stream tributaries, and surrounding area of the river Chitral, Shyok suture zone district Chitral, Pakistan. To understand the geochemical features of 113 sediment, samples were collected from the Mirkhani and Drosh area. Then, different statistical tools including the geo-accumulation index (Igeo), cluster analysis (CA), principal component analysis (PCA), and ecological risk assessment (ERA) were used to unravel the origin, intensity, and exposure level of PTMs to control risk and restore the ecosystem within the study area. The results for the PTMs namely nickle (Ni), chromium (Cr), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), and cobalt (Co) in Mirkhani and Drosh were in the following ranges: 10–150, 15–210, 15–250, 0.08–1.00, 10–70, 76–240 and 14–51; and 13–240, 17–210, 15–150, 0.08–0.60, 7–140, 47–150 and 13–36 mg/kg, respectively. In consequence, the potential ecological risk caused by Pb, Ni, Cu, Co, Cr, and Zn is reflected by the percentages of samples with an ecological risk index (ERI) greater than one which were 100%, 91%, 100%, 100%, 92%, and 100%, respectively. However, the overall mean decreasing order of ecological risk of PTMs in the district Chitral was Pb > Ni > Cu > Co > Cr > Zn > Cd. Moreover, the PCA yielded 78% variability which indicated that mineral prospects play an important role in the contamination of sediment. Furthermore, the mineral phases of Pb and Zn suggested supersaturation, while that for Cd revealed unsaturation. The results of Igeo, ERI, and CA indicated contamination of PTMs in the study area. The ERI value of Pb, Ni, Cu, Co, Cr, and Zn was higher than 1 suggesting an ecological risk in the study area. Moreover, the current study showed the dominance of geogenic contamination with major contributions from ultramafic rock and known mineral prospects. Therefore, contaminated sediment of the Shyok suture zone is extremely detrimental to the aquatic ecosystem of the study area.  相似文献   

Multi-factor impact analysis of agricultural production in Bangladesh with climate change   总被引：1，自引：0，他引：1  

Alex C. Ruane  David C. Major  Winston H. Yu  Mozaharul Alam  Sk. Ghulam Hussain  Abu Saleh Khan  Ahmadul Hassan  Bhuiya Md. Tamim Al Hossain  Richard Goldberg  Radley M. Horton  Cynthia Rosenzweig 《Global Environmental Change》2013,23(1):338-350

Diverse vulnerabilities of Bangladesh's agricultural sector in 16 sub-regions are assessed using experiments designed to investigate climate impact factors in isolation and in combination. Climate information from a suite of global climate models (GCMs) is used to drive models assessing the agricultural impact of changes in temperature, precipitation, carbon dioxide concentrations, river floods, and sea level rise for the 2040–2069 period in comparison to a historical baseline. Using the multi-factor impacts analysis framework developed in Yu et al. (2010), this study provides new sub-regional vulnerability analyses and quantifies key uncertainties in climate and production. Rice (aman, boro, and aus seasons) and wheat production are simulated in each sub-region using the biophysical Crop Environment REsource Synthesis (CERES) models. These simulations are then combined with the MIKE BASIN hydrologic model for river floods in the Ganges-Brahmaputra-Meghna (GBM) Basins, and the MIKE21 Two-Dimensional Estuary Model to determine coastal inundation under conditions of higher mean sea level. The impacts of each factor depend on GCM configurations, emissions pathways, sub-regions, and particular seasons and crops. Temperature increases generally reduce production across all scenarios. Precipitation changes can have either a positive or a negative impact, with a high degree of uncertainty across GCMs. Carbon dioxide impacts on crop production are positive and depend on the emissions pathway. Increasing river flood areas reduce production in affected sub-regions. Precipitation uncertainties from different GCMs and emissions scenarios are reduced when integrated across the large GBM Basins’ hydrology. Agriculture in Southern Bangladesh is severely affected by sea level rise even when cyclonic surges are not fully considered, with impacts increasing under the higher emissions scenario.  相似文献   

Landslide susceptibility analysis with a bivariate approach and GIS in Northern Iran   总被引：3，自引：3，他引：0  

Ataollah Kelarestaghi  Hassan Ahmadi 《Arabian Journal of Geosciences》2009,2(1):95-101

Globally, landslides cause hundreds of billions of dollars in damage and hundreds of thousands of deaths and injuries each year. A landslide susceptibility map describes areas where landslides are likely to occur in the future by correlating some of the principal factors that contribute to landslides with the past distribution of landslides. A case study is conducted in the mountainous northern Iran. In this study, a landslide susceptibility map of the study area was prepared using bivariate method with the help of the geographic information system. Area density (bivariate) method was used to weight landslide-influencing data layers. An overlay analysis is carried out by evaluating the layers obtained according to their weight and the landslide susceptibility map is produced. The study area was classified into five hazard classes: very low, low, moderate, high, and very high. The percentage distribution of landslide susceptibility degrees was calculated. It was found that about 26% of the study area is classified as very high and high hazard classes.  相似文献   

Geology and petrography of the Nagar Parkar igneous complex,southeastern Sindh,Pakistan: The Kharsar body     

M. Qasim Jan  M. Hassan Agheem  Amanullah Laghari  Suhail Anjum 《Journal of the Geological Society of India》2017,89(1):91-98

Kharsar hill is one of many granitic plutons comprising the Nagar Parkar igneous complex. The eastern part of the hill is occupied by grey-pink granite (earlier) and the western part by pink granite (later). They are composed of perthite, quartz, and plagioclase, with minor opaque oxide, biotite, titanite, local amphibole, and secondary chlorite, epidote, leucoxene/titanite. The pink granite is characterized by the presence of mafic clots. Both the granitoids are intruded by microgranite/aplite, and porphyritic mafic and rhyolite dykes, locally in swarms. These are abundant in a NE trending 200 m wide zone cutting the entire granite hill. The dykes may extend over 1 km in length and >10 m in thickness, but most are < 100 m in length. The felsic dykes are of several generations; some are associated with the two varieties of granite, others are contemporaneous with the rhyolite and mafic dykes. The mafic dykes can be grouped into two types one of which contains hornblende and the other augite as the principal mafic mineral. Major element analyses suggest that the granitic rocks are metaluminous. The Kharsar granites, like the others in Nagar Parkar, may be an extension of the Malani igneous suite of Rajasthan. The occurrence of bimodal mafic-felsic dykes and petrographic variation in the mafic dykes are briefly discussed.  相似文献   

Use of remote sensing data in comprehending an extremely unusual flooding event over southwest Bangladesh     

Chowdhury  Ehsan H.  Hassan  Quazi K. 《Natural Hazards》2017,88(3):1805-1823

Natural Hazards - Flooding is one of the natural disasters that affect the livelihood of the people living in the floodplains, like Bangladesh. Here, we proposed to employ SAR satellite images in...  相似文献   

Assessment of proposed approaches for bathymetry calculations using multispectral satellite images in shallow coastal/lake areas: a comparison of five models     

Hassan Mohamed  AbdelazimNegm  Mahmoud Salah  Kazuo Nadaoka  Mohamed Zahran 《Arabian Journal of Geosciences》2017,10(2):42

Bathymetric information for shallow coastal/lake areas is essential for hydrological engineering applications such as sedimentary processes and coastal studies. Remotely sensed imagery is considered a time-effective, low-cost, and wide-coverage solution for bathymetric measurements. This study assesses the performance of three proposed empirical models for bathymetry calculations in three different areas: Alexandria port, Egypt, as an example of a low-turbidity deep water area with silt-sand bottom cover and a depth range of 10.5 m; the Lake Nubia entrance zone, Sudan, which is a highly turbid, unstable, clay bottom area with water depths to 6 m; and Shiraho, Ishigaki Island, Japan, a coral reef area with varied depths ranging up to 14 m. The proposed models are the ensemble regression tree-fitting algorithm using bagging (BAG), ensemble regression tree-fitting algorithm of least squares boosting (LSB), and support vector regression algorithm (SVR). Data from Landsat 8 and Spot 6 satellite images were used to assess the performance of the proposed models. The three models were used to obtain bathymetric maps using the reflectance of green, red, blue/red, and green/red band ratios. The results were compared with corresponding results yielded by two conventional empirical methods, the neural network (NN) and the Lyzenga generalised linear model (GLM). Compared with echosounder data, BAG, LSB, and SVR results demonstrate higher accuracy ranges from 0.04 to 0.35 m more than Lyzenga GLM. The BAG algorithm, producing the most accurate results, proved to be the preferable algorithm for bathymetry calculation.  相似文献   

Development of functionalized carrageenan,chitosan and alginate as polymeric chelating ligands for water softening     

K. A. Ali  M. E. Hassan  M. M. M. Elnashar 《International Journal of Environmental Science and Technology》2017,14(9):2009-2014

Chitosan, carrageenan and alginate are among the most abundant biopolymers in nature. They were prepared in uniform beads shape with a diameter of 2 mm ± 10%, using the encapsulator for removal of calcium, magnesium and iron cations from hard water. Solutions of 100–500 mg/L were prepared from each cation, and the detection of cations was carried out using atomic absorption spectrometer. Carrageenan and chitosan were able to chelate the three cations without further modification. However, alginate beads succeeded to chelate iron and magnesium and failed to chelate any calcium ions; in contrast, it increased the initial calcium concentration! That could be due to the pre-cross-linking of alginate beads using calcium chloride solution, which may be leaked back to the solution. However, grafting the alginate beads with polyethyleneimine and bromoacetic acid rectified this problem and the new functional group, –COOH, has been proved using the FT-IR. Optimization of the results in terms of beads weight (0.25–3.0 g) and cations concentrations (100–500 mg/L) has shown that most biopolymeric beads can chelate 85–100% of the cations in concentrations up to 500 mg/L. According to our finding, we came up with the recommendation to use chitosan for chelation of calcium and iron as it showed 100% chelation efficiency of both cations, whereas carrageenan is highly recommended for chelation of iron and magnesium, as it showed 100 and 98% chelation efficiency, respectively. Further work can be done on the reusability of the beads and scale up for the industrial use.  相似文献   

Composition,radioactivity, and possible applications of kaolin deposits of Sinai,Egypt     

Ahmed El-Kammar  Hassan Taha Abu-Zied  Mohamed Galal  Dina Osman 《Arabian Journal of Geosciences》2017,10(21):463

This work discusses the composition, radioactivity, and possible utilization of the kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Carboniferous (Wadi Khaboba) and Early Cretaceous (Wadi Iseila and Abansakar) ages. The characterization of kaolin was done by microscopic and SEM examination, supported by XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite, as the main constituent, associated with subsidiary dickite and halloysite, and minor contribution of smectite and illite. The most dominant non-clay mineral is quartz, besides minor gypsum, dolomite, and hematite. Ferrugination dominates, in most cases, at the upper boundaries of the kaolin lenses, suggesting possible supergene activity. The high Al₂O₃/SiO₂ ratio for the Cretaceous kaolin (0.54, in average) specifies its better grade relative to the Carboniferous kaolin (0.43, in average). The kaolin of the middle part of lens C in Wadi Iseila contains Si/Al molecular ratio of about unity, suggesting high-grade kaolin. The Carboniferous kaolin has enriched the radionuclides: U, Th, and Ra (at disequilibrium state due to leaching of eU relative to Ra) and the REE, relative to that of the Cretaceous age. The Carboniferous kaolin is characterized by a higher contribution of HREE (zircon signature), whereas LREE seems to be more influential for the Early Cretaceous kaolin (monazite signature). In spite of the very high CIA index (93 to 99), none of the analyzed kaolin deposits displays Ce abnormality. The high radioactivity of some Carboniferous kaolin can be a serious impediment for its utilization or its exportation. The kaolin of Sinai does not satisfy the international standards for paperwork industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of oxides of iron, magnesium, calcium, sodium, and potassium and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramics manufacturing in the global market. Grade 3 kaolin (< 30%, Al₂O₃) can be used in the manufacturing of white Portland cement and red glaze manufacturing on both local and global markets.  相似文献   

Mineralogy and physico-chemical properties of Wadi Badaa clays (Cairo-Suez district,Egypt): a prospective resource for the ceramics industry     

Sherif Kharbish  Hassan I. Farhat 《Arabian Journal of Geosciences》2017,10(7):174

The Wadi Badaa (WB) Upper Miocene clays, Cairo-Suez district, Egypt, represent materials for the ceramic production. The clay raw materials are composed mainly of smectite and kaolinite with minor quartz, calcite, and rare feldspar. The plasticity indices vary between 24 and 30%, suggesting that these clays are plastic raw materials. IR bands of the investigated clays were observed at 3695, 3619, 1032, 916, 794, 690, 534, 466, and 423 cm^?1 for kaolinite; at 3436, 1635, 916, and 466 cm^?1 for smectite; and at 1179, 1104, 794, 690, and 466 cm^?1 for quartz. The <2 μm particle sizes of samples are relatively abundant in clays (～33%), which is adequate for uses of the ceramic products because of containing fine particle sizes. The studied WB clays contain 7.95 and 12.35% moisture water and interlayer water, respectively, with a maximum drying shrinkage of 7.87% at room temperature; therefore, the WB clays could be used in the ceramic manufacture.  相似文献