Palynostratigraphy and palaeoenvironmental significance of the Cretaceous palynomorphs in the Qattara Rim-1X well,North Western Desert,Egypt     

Maher I. El-Soughier  Amr S. Deaf  Magdy S. Mahmoud 《Arabian Journal of Geosciences》2014,7(8):3051-3068

Palynological and palynofacies analyses were carried out on some Cretaceous samples from the Qattara Rim-1X borehole, north Western Desert, Egypt. The recorded palynoflora enabled the recognition of two informal miospore biozones arranged from oldest to youngest as Elaterosporites klaszii-Afropollis jardinus Assemblage Zone (mid Albian) and Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (late Albian–mid Cenomanian). A poorly fossiliferous but however, datable interval (late Cenomanian–Turonian to ?Campanian–Maastrichtian) representing the uppermost part of the studied section was also recorded. The palynofacies and visual thermal maturation analyses indicate a mature terrestrially derived organic matter (kerogen III) dominates the sediments of the Kharita and Bahariya formations and thus these two formations comprise potential mature gas source rocks. The sediments of the Abu Roash Formation are mostly dominated by mature amorphous organic matter (kerogen II) and the formation is regarded as a potential mature oil source rock in the well. The palynomorphs and palynofacies analyses suggest deposition of the clastics of the Kharita and Bahariya formations (middle Albian and upper Albian–middle Cenomanian) in a marginal marine setting under dysoxic–anoxic conditions. By contrast, the mixed clastic-carbonate sediments of the Abu Roash Formation (upper Cenomanian–Turonian) and the carbonates of the Khoman Formation (?Campanian–Maastrichtian) were mainly deposited in an inner shallow marine setting under prevailing suboxic–anoxic conditions as a result of the late Cenomanian and the Campanian marine transgressions. This environmental change from marginal to open (inner shelf) basins reflects the vertical change in the type of the organic matter and its corresponding hydrocarbon-prone types. A regional warm and semi-arid climate but with a local humid condition developed near/at the site of the well is thought to have prevailed.  相似文献   

Integrated geophysical study to explore the groundwater in the tectonic plain between Wadi El Mahash and Wadi Um Markhah,Southwest Sinai,Egypt     

Adel D. M. Kotb  Galal H. G. Hussein  Mahmoud A. ElHefnawy 《Arabian Journal of Geosciences》2014,7(6):2179-2197

South Sinai Governorate acts as one of the most vital regions in Egypt for its location and natural resources. This governorate has a special economic importance to increase the national income due to its tourism expansion and petroleum. The fresh water is transferred from Cairo through pipelines to cover the demands of local inhabitants in the north Sinai governorate and the capital city of south Sinai governorate. The groundwater exploration and exploitation in this area have a great importance to cover the need of water for the different activities (tourism, petroleum, and agriculture) and to achieve a maximum development in this region. Therefore, the present study deals with using the different geophysical exploration techniques (magnetic, geoelectrical resistivity and shallow refraction seismic) to detect the groundwater aquifer or aquifers in the area between latitudes 27°52′ and 28°05′?N and longitudes 33°55′ and 34°05′?E. in southwestern Sinai—Egypt. The main results of these tools are the maximum depth to the basement surface 180 m and structure elements which affected on this area are represented by a number of normal faults have a trends (NNW–SSE and ENE–WSW) making two grabens isolated by one horst. Tariff Sandstone bed recorded as water-bearing formation and the basement ridge gates in the gulf direction are not capable to pass the ground water from the study area to the Gulf of Suez. Finally, the best locations for drilling groundwater wells were selected from the decision map which generated by using the GIS technique.  相似文献   

Shear strength and pore-water pressure characteristics of sandy soil mixed with plastic fine   总被引：1，自引：0，他引：1  

M. Bayat  E. Bayat  H. Aminpour  A. Salarpour 《Arabian Journal of Geosciences》2014,7(3):1049-1057

Recent earthquake case histories have revealed the liquefaction of mixtures of sand and fine particles during earthquakes. Different from earlier studies which placed an emphasis on characterisation of liquefaction in terms of the induced shear stress required to cause liquefaction, this study adopted a strain approach because excess pore-water pressure generation is controlled mainly by the level of induced shear strains. The current study includes the results of a set of laboratory tests carried out on sand specimens with the same relative densities and variation in the plastic fines (kaolinite or bentonite) contents ranging from 0 to either 30 % and consolidated at mean confining pressure of 100, 200 and 300 kPa using static triaxial test apparatus, in order to study the influence of fine content and other parameters on the undrained shear strength and liquefaction potential of clayey sand specimens; also, pore-water pressures in the specimens are discussed. Results of tests show that the peak strength decreases as the fines (kaolinite or bentonite) content increases up to a threshold content of fines (FC_th) after which, increases in plastic fine content lead to improve the peak shear strength of specimens, and also the ultimate steady-state strength has been improved due to the increased in plastic fines content. Also, pore pressure build-up in clayey sands is generally slower than that observed in pure sand.  相似文献   

Elastic properties of six silicate garnet end members from accurate ab initio simulations   总被引：1，自引：1，他引：0  

Alessandro Erba  Agnes Mahmoud  Roberto Orlando  Roberto Dovesi 《Physics and Chemistry of Minerals》2014,41(2):151-160

The elastic properties of six silicate garnet end members, among the most important rock-forming minerals, are investigated here for the first time via accurate ab initio theoretical simulations. The Crystal program is used, which works within periodic boundary conditions and allows for all-electron basis sets to be adopted. From the computed elastic tensor, Christoffel’s equation is solved along a set of crystallographic directions in order to fully characterize the seismic wave velocity anisotropy in such materials. Polycrystalline isotropic aggregate elastic properties are derived from the computed single-crystal data via the Voigt-Reuss-Hill averaging procedure. Transferability of the elastic properties from end members to their solid solutions with different chemical compositions is also addressed.  相似文献   

Uncertainty of climate change impact on crop characteristics: a case study of Moghan plain in Iran     

Sharafati  Ahmad  Moradi Tayyebi  Mahmoud  Pezeshki  Elnaz  Shahid  Shamsuddin 《Theoretical and Applied Climatology》2022,149(1-2):603-620

Theoretical and Applied Climatology - Crop yield is one of the most critical factors in the food security chain. Climate plays a crucial role in crop water productivity in rainfed and irrigated...  相似文献   

Effect of grading characteristics on the undrained shear strength of sand: review with new evidences     

E. Bayat  M. Bayat 《Arabian Journal of Geosciences》2013,6(11):4409-4418

In this paper, the shear strength of saturated pure sand and sand–silt mixture is evaluated by monotonic undrained triaxial tests that were carried out on reconstituted specimens at same relative densities and a constant confining pressure (σ ₃?=?300 kPa). The test results were used to conclude on the effect of low non-plastic contents (0–20 %) and grading characteristics on the liquefaction resistance of the sand. The test results indicate that the undrained residual strength reduced with the increase of non-plastic fine content. Also, shear strength of gap-graded sand mixed with low non-plastic fine content increases with decrease in effective size (D ₅₀). In other words, in this state, we can use the D ₅₀ as a parameter to control of silty sand’s undrained resistance. Besides, the undrained residual strength of pure sand specimens with same effective size increases due to increase of coefficient of uniformity (C _u).  相似文献   

Viscothermal instability in Keplerian disc and formation of overdense regions     

Mahmoud Gholipour  Mohsen Nejad-Asghar 《Astrophysics and Space Science》2013,343(1):65-68

Viscosity have a significant effect in evolution of accretion disc. In this paper, we investigate the thermal effect of viscosity in the accretion disc that may cause instability to produce overdense regions through it. For this purpose, the linear perturbation method is used to investigate instability on this so-called viscothermal effect. The results show that instability can occur in accretion disc so that larger overdense regions are formed at far greater distance of protostar. This mechanism may explain formation of larger protoplanets farther from protostars.  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   

Removal of Hydrogen Sulfide by Physico‐Biological Filter Using Mixed Rice Husk Silica and Dried Activated Sludge     

Seyed Mahmoud Mehdinia  Puziah Abdul Latif  Hassan Taghipour 《洁净——土壤、空气、水》2013,41(10):949-954

This study investigated the effectiveness of a new packing material, namely mixed rice husk silica with dried activated sludge for removing H₂S. Dried sewage sludge was collected from Putrajaya sewage treatment plant in Malaysia. Rice husk silica was prepared at temperature of 800°C, after acid leaching and mixed with dried sewage sludge to be utilized in a polyvinyl chloride filter. The system was operated under variable conditions of two parameters, different inlet gas concentration and different inlet flow rate. H₂S was passed through the filter with one liter of the packing material. More than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 90–45 s and 300 ppm inlet concentration was observed. However, the RE decreased to 96.87% with the EBRT of 30 s. The maximum elimination capacity (EC) of 52.32 g/m³/h was obtained with the RE of 96.87% and H₂S mass loading rate of 54 g/m³/h, while at the RE of 99.96%, maximum EC was 26.99 g/m³/h with the H₂S mass‐loading rate of 27 g/m³/h. A strong significant correlation between increasing of H₂S mass loading rate and pressure drop was also detected (p < 0.01). Maximum pressure drop was 3.0 mm H₂O after 53 days of operating time, the EBRT of 30 s, and 54 g/m³/h of H₂S loading rate. These observations suggest that the mixture of rice husk silica with dried activated sludge is a suitable physico‐biological filter for H₂S removal.  相似文献