Distribution and Influence of Iron Phases on the Physico—Chemical Properties of Phyllosilicates     

MERVATSAIDHASSAN SAYEDMAHMOUDSALEM 《中国地球化学学报》2002,21(1):29-39

Clay minerals from different Cretaceous stratigraphic successions of Egypt were investigated using XRD,DTA,dissolution analysis(DCB),IR,Moessbauer and X-band Electron Spin Resonance(ESR) spectroscopies.The purity of the samples and the degree of structural order were determined by XRD.The location of Fe in the octahedral sheet is characterized by absorption bands at-875cm^-1 assigned as Al-OH-Fe which is present after chemical dissolution of free iron.The Moessbauer spectra of these clays sow two doublets with isomer shift and quadrupole splitting typical of octahedral coordinated Fe^3 ,in addition to third doubler with hyperfine parameter typical of Fe^2 in the spectra of Abu-Had kaolinite (H)sample.6-lines magnetic hyperfine components which are consistent with those of hematite are confirmed in the spectra of both Isel and Rish kaolinite samples.Goethite was confirmed by both IR and DTA.Multiple nature of ESR of these clays suggested structural Fe in distorted octaedral symmetry and as non-structural Fe.Little dispersion and low swelling indices as well as incomplete activaiton of investigated montmorillonite samples by NaCO3 appear to be due to incomplete disaggregation of montmorillonite particles.This can be explained by the ability of Fe-gel to aggregate the montmorillonite into pseudo-particles and retard the rigid-gel structure.However,extraction of this ferric amorphous compound by dithonite treatment recovers the surface properties of the montmorillonite samples.On the other hand,amounts and site occupation of Fe associated with kaolinite samples show a negative correlation with the parameters used to describe the degree of crystalline perfection,color,brightness and vitrification range of these kaolinite samples.  相似文献   

Seismic performance of high-rise buildings in selected regions in Saudi Arabia according to different seismic codes     

Sayed Mahmoud  Mohamed Alsearheed  Waleed Abdallah 《地震工程与工程振动(英文版)》2021,(1):179-191

The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic capacity.Based on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of hazard.This study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are selected.The code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as well.Significant differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications.  相似文献   

The Quaternary development of tributary channels to the Nile River at Kom Ombo area,Eastern Desert of Egypt,and their implication for groundwater resources     

Mohammed El Bastawesy  Abdallah Faid  El Sayed El Gammal 《水文研究》2010,24(13):1856-1865

The dry wadis ‘ephemeral channel’ constituting the main tributaries to the Nile River in Kom Ombo are structurally and tectonically controlled and exhibit complex drainage pattern. This complicated drainage pattern is inherited from the morpho‐tectonic evolution of the ancestral Nile River (‘Protonile’), which drained the Eastern Desert during the Middle Pleistocene. A digital elevation model derived from Shuttle Radar Topography Mission data is used to delineate the contemporary drainage networks and their catchments. Satellite images acquired during a flash flood event were used to validate the delineated watershed divides and flow pathways, particularly where the courses of dry wadis are interlocked. Currently, the westward flow of Wadi Abu‐Suberah is derived from a small area in the Eastern Desert, as the palaeo‐upper reaches of this wadi were captured due to tectonic movements along NW/SE and N/S faults by wadis in the Kharit and Elewa areas. The influence of these tectonic movements on groundwater distribution is also shown where the deep Nubian aquifer discharges its water into the Quaternary aquifer through fault planes. The northward flowing ‘Protonile’ main course has tectonically shifted from the Gallaba plain in the Western Desert, eastward to the current Nile River course. This shift has produced several cut‐off segments of the palaeo‐tributary drainage that was originally flowing westward towards the old ‘Protonile’ main course in the Gallaba plain. However, these segments have reversed their surface run‐off flow directions eastward towards the current Nile course; they could include potential groundwater resources, as their alluvium may be still recharged by the Nile River. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Origin,age, and significance of deep‐seated granulite‐facies migmatites in the Barrow zones of Scotland,Cairn Leuchan,Glen Muick area          下载免费PDF全文

Richard M. Palin  Abdul B. Sayed  Richard W. White  Regina Mertz‐Kraus 《Journal of Metamorphic Geology》2018,36(8):1071-1096

Petrological modelling of granulite‐facies mafic and semipelitic migmatites from Cairn Leuchan, northeast Scotland, has provided new constraints on the pressure (P) and temperature (T) conditions of high‐grade metamorphism in the type‐locality Barrow zones. Phase diagrams constructed in the Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–O₂ system have constrained the P?T conditions of peak metamorphism in the Glen Muick region of the upper sillimanite zone (Sill+Kfs) to have been at least ～840°C at ～9 kbar (high‐P granulite facies). These conditions are ～120°C and ～3 kbar higher than those recorded by lower sillimanite zone (Sill+Ms) units located only a few kilometres away to the southeast at Glen Girnock, indicating the presence of a significant thermal and barometric high exposed within the Scottish Dalradian, and supporting previous suppositions of a potential tectonic break between the two regions. U–Pb zircon geochronology performed on these mafic migmatites produced ages of c. 540–470 Ma from grains with both igneous and metamorphic morphological characteristics. Their basaltic protoliths likely formed during a period of volcanism dated at c. 570 Ma, associated with passive‐margin extension prior to the onset of Iapetus Ocean closure, and high‐grade metamorphism and partial melting is interpreted to have taken place at c. 470 Ma, synchronous with sillimanite‐grade metamorphism recorded elsewhere in the Dalradian. These high‐grade Cairn Leuchan lithologies are interpreted as representing a fragment of Grampian Terrane lower crust that was exhumed via displacement along a steeply dipping tectonic discontinuity related to the Portsoy–Duchray Hill Lineament, and are not pre‐Caledonian Mesoproterozoic basement, as suggested by some previous studies. Veins within some mafic migmatites in the Cairn Leuchan area, composed almost entirely (>80%) of garnet, with minor quartz, plagioclase, amphibole, and clinopyroxene, are interconnected with leucosomes and are interpreted to represent former garnet‐bearing melt segregations that have been locally drained of almost all melt. Thus, mafic components of the lower crust, currently underlying relatively lower grade metasediments exposed to the southeast, may represent a potential source rock for widely documented, post‐orogenic felsic plutons, sills, and dykes that occur throughout the Grampian Terrane.  相似文献   

Contribution of gravity and magnetic data in delineating the subsurface structure of Hammam Faroun area, Gulf of Suez, Egypt     

Essam Aboud  El Sayed Selim  Ahmed El Bishlawy 《Arabian Journal of Geosciences》2011,4(1-2):249-257

The Hammam Faroun has a particular importance due to its geothermal activity which constitutes the main geothermal resource of Egypt. The area is located on the Sinai Peninsula, a subplate bounded by two seismically active structural zones along the Gulf of Suez and Gulf of Aqaba. High-resolution ground-based gravity and magnetic data are available for the entire Hammam Faroun area, acquired as part of a national project to explore for mineral, geothermal, and hydrocarbon resources. Gravity and magnetic data were analyzed using Source Edge Detection and Source Parameter Imaging (SPI) techniques to image subsurface structures. These analyses show that the area is characterized by a set of northwest-striking faults lying parallel to the Gulf of Suez. Orthogonal patterns are also present, possibly related to rifting of the Gulf of Suez. Depth analysis using the SPI method indicates that surface faults extend to 5-km depth. Analysis of potential-field data elucidates the structurally complex subsurface structure of the Hammam Faroun area.  相似文献   

Interactions between the surface water and groundwater in the western shoreline of Lake Nasser, Upper Egypt     

Ali M. Hamdan  Sayed A. Selim  Mohamed M. Abdallah 《Arabian Journal of Geosciences》2013,6(1):77-84

The present study indicates that the factors controlling the hydraulic relation between surface water and groundwater at the western lake shoreline change from one locality to another. This depends upon the lithological characteristics and the major structures. In the southern sectors, sedimentation at the bottom and sides of the lake prevents the water movement to the Nubian sandstone aquifer. The potentiometric map reveals that the water level altitudes range between 170 m in the vicinity of the lakeshore line and 110 m west of the lake. The groundwater flow lines show that the main recharge to the aquifer comes from the southwest direction, as well as from the lake inland to variable distances (about 30 Km). During the present study, Darcy’s law was applied to calculate the recharge from the western shoreline of Lake Nasser to the adjacent Nubian aquifer. The maximum value of seepage was at Garf Hussein (27.71?×?10⁶ m³/year), which may be related to high permeability and hydraulic gradient. Also, it may be related to the N–S strike faults that cut the area on both sides of the Lake, and the groundwater is expected to have free circulation through the faults of this trend. The minimum value was recorded in Adindan section (0.61?×?10⁶ m³/year). This may be related to the limited recharge from the lake to the aquifer, due to the sedimentation that dislocates this recharge.  相似文献   

Time-fractional KdV equation for electron-acoustic waves in plasma of cold electron and two different temperature isothermal ions     

Sayed A. El-Wakil  Essam M. Abulwafa  Emad K. El-shewy  Abeer A. Mahmoud 《Astrophysics and Space Science》2011,333(1):269-276

The time fractional KdV equation is derived for small but finite amplitude electron-acoustic solitary waves in plasma of cold electron fluid with two different temperature isothermal ions. The effects of the time fractional parameter on the electrostatic solitary structures are presented. It is shown that the effect of time fractional parameter can be used to modify the amplitude of the electrostatic waves (viz. the amplitude, width and electric field) of the electron-acoustic solitary waves. The model may provide a possible explanation for the low-frequency component of the broadband electrostatic noise in the plasma sheet boundary layer of the Earth’s magnetotail where the electron beams are not present.  相似文献   

Earthquake-induced pounding between equal height multi-storey buildings considering soil-structure interaction     

Sayed Mahmoud  Ayman Abd-Elhamed  Robert Jankowski 《Bulletin of Earthquake Engineering》2013,11(4):1021-1048

The present paper investigates the coupled effect of the supporting soil flexibility and pounding between neighbouring, insufficiently separated equal height buildings under earthquake excitation. Two adjacent three-storey structures, modelled as inelastic lumped mass systems with different structural characteristics, have been considered in the study. The models have been excited using a suit of ground motions with different peak ground accelerations and recorded at different soil types. A nonlinear viscoelastic pounding force model has been employed in order to effectively capture impact forces during collisions. Spring-dashpot elements have been incorporated to simulate the horizontal and rotational movements of the supporting soil. The results of the numerical simulations, in the form of the structural nonlinear responses as well as the time-histories of energy dissipated during pounding-involved vibrations, are presented in the paper. In addition, the variation in storeys peak responses and peak dissipated energies for different gap sizes are also shown and comparisons are made with the results obtained for colliding buildings with fixed-base supports. Observations regarding the incorporation of the soil-structure interaction and its effect on the responses obtained are discussed. The results of the study indicate that the soil-structure interaction significantly influences the pounding-involved responses of equal height buildings during earthquakes, especially the response of the lighter and more flexible structure. It has been found that the soil flexibility decreases storey peak displacements, peak impact forces and peak energies dissipated during vibrations, whereas it usually leads to the increases in the peak accelerations at each storey level.  相似文献   

Determination of sedimentary cover and structural trends in the Central Sinai area using gravity and magnetic data analysis     

El Sayed Selim  Essam Aboud 《Journal of Asian Earth Sciences》2012,43(1):193-206

The present study is an attempt to determine the sedimentary cover, and structural trends in the central part of Sinai Peninsula, Egypt. This study has been implemented by the integration of gravity and magnetic methods. Gravity data has been used for 2D modelling along some profiles perpendicular to the main structural trends of the study area. Magnetic data will be analyzed to determine the depth to the basement surface. The depths obtained from magnetic data will be used as a control points in the gravity modelling in order to minimize the error and facilitate the iteration of the suggested models. The basement relief map from magnetic and gravity output has been produced. This map indicates that, the basement depths, generally, increases from south to north and from east to west direction of the study area. The sedimentary cover is about 1.5-2 km in the southern part and increases to more than 4 km in the northeastern and western parts and changes gradually in the other parts of the study area. Results of structural trend analysis indicate that, the study area is greatly affected by several structural trends; N-S, E-W, NW-SE, and NNE-SSW directions. These trends are associated with the Baltim fault trend, Tethyan trend, Gulf of Suez, and Aqaba trend, respectively.  相似文献   

Comparison of fast elimination of Cr(VI) by alumina nanofiber and alumina nanoporous     

H. Hosseini Shekarabi  A. H. Javid  P. Aberoomand Azar  A. H. Hasani 《International Journal of Environmental Science and Technology》2017,14(4):803-812

The goal of this study is examination of the mixture between adsorption and permeation process for removing chromium (VI) from the water. Two types of supported membranes are developed: The first one which was made by sol–gel method is called nanoporous and the second one which was made by electrospinning is called nanofiber. The sorption capacity of nanoporous and nanofiber is examined in single batch experiments at various pH values, and it is found that maximum chromium removal is observed for both nanoporous and nanofiber at pH 3.5. Adsorption studies illustrated that the Cr(VI) adsorption onto alumina nanoporous and nanofiber is affected by changes in pH, contact time, dosage of adsorbent, concentration of chromium and solution volume. Langmuir and Freundlich isotherms can be used to explain the adsorption equilibria of Cr(VI) onto alumina nanoporous and nanofiber. It was found that balance adsorption data adequate Langmuir isotherm more than Freundlich model. Adsorption kinetics was found to be fitted to pseudo-second order and Weber and Morris model. The output of multiple linear regressions was run for the second-order response surface model implied that the linear agents of pH, sorbent dosage and Cr(VI) concentration are more significant factors. Manufacturing electrospun alumina nanofiber and sol–gel nanoporous with these cheap materials, renewable and fast methods are so important although the removal percentage is significant.  相似文献